Circuit arrangement and oscillator

Abstract

Circuit device and oscillator, in the case where a power supply voltage is low voltage, can achieve proper temperature compensation. Circuit device contains: oscillation circuit, which makes the oscillator oscillate and generates an oscillation signal; temperature compensation circuit, which has an operational amplifier (OPD), based on the temperature detection voltage (VTS) from the temperature detection circuit, the temperature compensation voltage (VCP) of the oscillation frequency of the oscillation signal is output to the oscillation circuit; and reference voltage generation circuit for temperature compensation, which generates a reference voltage (VRC) for temperature compensation and outputs it to the temperature compensation circuit. The input limit voltage (PINLM) of the first input terminal of the operational amplifier (OPD) has a first polarity temperature characteristic as one of positive and negative, and the reference voltage (VRC) input to the first input terminal of the operational amplifier (OPD) has a first polarity temperature characteristic same as the polarity of the input limit voltage.

Description

Technical Field

[0001] This invention relates to circuit devices and oscillators, etc. Background Technology

[0002] In circuit devices that oscillate oscillators such as quartz oscillators, temperature compensation of the oscillation frequency is performed. For example, a circuit device for performing such temperature compensation is disclosed in Patent Document 1. In this circuit device, temperature compensation of the oscillation frequency of the oscillator, which varies with temperature, is performed, for example, by controlling the capacitance of a variable capacitor circuit of the oscillation circuit based on a temperature compensation voltage.

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 2023-90099 Summary of the Invention

[0006] However, it has been determined that there is a problem that makes it difficult to ensure the output voltage range of the temperature compensation voltage due to factors such as the decrease in power supply voltage.

[0007] One aspect of this disclosure relates to a circuit arrangement comprising: an oscillation circuit that causes an oscillator to oscillate to generate an oscillation signal; a temperature compensation circuit having an operational amplifier that outputs a temperature compensation voltage of the oscillation frequency of the oscillation signal to the oscillation circuit based on a temperature detection voltage from a temperature detection circuit; and a temperature compensation reference voltage generation circuit that generates a temperature compensation reference voltage and outputs it to the temperature compensation circuit, wherein the input limit voltage of a first input terminal of the operational amplifier has a temperature characteristic of a first polarity being either positive or negative, and the reference voltage input to the first input terminal of the operational amplifier has a temperature characteristic of the same first polarity as the temperature characteristic of the input limit voltage.

[0008] Furthermore, other aspects of this disclosure relate to an oscillator that includes the circuitry described above and the oscillator. Attached Figure Description

[0009] Figure 1 This is an example of the structure of the circuit device in this embodiment.

[0010] Figure 2 This is a detailed structural example of the circuit device and oscillator in this embodiment.

[0011] Figure 3 This is an example of the structure of a temperature compensation circuit.

[0012] Figure 4 This is an explanatory diagram of temperature compensation processing.

[0013] Figure 5 This is an example of the structure of an oscillating circuit.

[0014] Figure 6 This is a structural example of a function current generation circuit.

[0015] Figure 7 This is an explanatory diagram of the method for generating temperature compensation current.

[0016] Figure 8 This is an example of the structure of an inverting amplifier circuit.

[0017] Figure 9 This is an example of the structure of an operational amplifier.

[0018] Figure 10 This is an illustration of the temperature characteristics of the temperature-compensated voltage.

[0019] Figure 11 This is an explanatory diagram of an amplifier circuit that converts current to voltage.

[0020] Figure 12 This is an example illustrating the temperature characteristics of the comparative method.

[0021] Figure 13 This is an example illustrating the temperature characteristics of the method in this embodiment.

[0022] Figure 14 This is another example of an operational amplifier structure.

[0023] Figure 15 This is an example illustrating the temperature characteristics of the comparative method.

[0024] Figure 16 This is an example illustrating the temperature characteristics of the method in this embodiment.

[0025] Figure 17 This is an example of the structure of a reference voltage generation circuit.

[0026] Figure 18 This is a structural example of a reference circuit.

[0027] Figure 19 These are other structural examples of the reference circuit.

[0028] Figure 20 These are other structural examples of the reference circuit.

[0029] Figure 21 This is an example of the structure of a regulator.

[0030] Explanation of reference numerals in the attached figures

[0031] 4…Oscillator; 10…Reverberant; 20…Circuit assembly; 30…Oscillating circuit; 32…Variable capacitor circuit; 40…Temperature compensation circuit; 42…Current generation circuit; 43…First-order correction circuit; 44…Higher-order correction circuit; 46…Current-to-voltage conversion circuit; 50…Temperature detection circuit; 60…Reference voltage generation circuit; 62…Reference circuit; 66…Regulator; 67…Voltage divider circuit; 68…Voltage generation circuit; 80…Output circuit; 90…Power supply circuit; 100…Control circuit; 110…Non-volatile memory; 140… Function current generation circuit; 141… Reference current generation circuit; 151… First compensation circuit; 152… Second compensation circuit; CX, CY… Variable capacitor element; ICP… Temperature compensation current; ICU… High-order current; OPD, OPD1, OPD2, OPE… Operational amplifier; PINLM… Input limit voltage; VCP… Temperature compensation voltage; VQMAX… Maximum voltage; VQMIN… Minimum voltage; VRC… Reference voltage; VRF, VRG… Voltage; VTS… Temperature detection voltage. Detailed Implementation

[0032] The following describes this embodiment. Furthermore, the embodiments described below are not intended to unduly limit the scope of the claims. Also, not all structures described in this embodiment are necessarily essential components.

[0033] 1. Circuit device

[0034] Figure 1 An example of the structure of the circuit device 20 of this embodiment is shown. The circuit device 20 of this embodiment includes an oscillation circuit 30, a temperature compensation circuit 40, and a reference voltage generation circuit 60. Furthermore, the circuit device 20 may include a temperature detection circuit 50. Additionally, the oscillator 10 is electrically connected to the circuit device 20, and for example, the oscillator 10 and the circuit device 20 constitute an oscillator. Furthermore, the circuit device 20 is not limited to... Figure 1 The structure can be transformed in various ways, such as omitting some of its constituent elements, adding other constituent elements, or replacing some of its constituent elements with other constituent elements.

[0035] The oscillator 10 is a component that generates mechanical vibration through an electrical signal. The oscillator 10 can be implemented, for example, using a quartz resonator or similar vibrating plate. For instance, the oscillator 10 can be implemented using a quartz resonator that undergoes thickness shear vibration with an AT cut or SC cut, a tuning fork type quartz resonator, or a double tuning fork type quartz resonator. For example, the oscillator 10 can be an oscillator built into a temperature-compensated quartz oscillator (TCXO) without a thermostatic bath, or an oscillator built into a thermostatic bath type quartz oscillator (OCXO) with a thermostatic bath. Furthermore, the oscillator 10 of this embodiment can also be implemented using various vibrating plates, such as those other than thickness shear vibration type, tuning fork type, or double tuning fork type, or piezoelectric resonators made of materials other than quartz. For example, the oscillator 10 can also be a SAW (Surface Acoustic Wave) resonator or a MEMS (Micro Electro Mechanical Systems) oscillator using a silicon oscillator formed on a silicon substrate.

[0036] Circuit device 20 is an integrated circuit device called an IC (Integrated Circuit). For example, circuit device 20 is an IC manufactured using semiconductor processes, which is a semiconductor chip on a semiconductor substrate with circuit elements formed thereon. Circuit device 20 operates based on a power supply voltage supplied from an external source.

[0037] The oscillation circuit 30 is a circuit that causes the oscillator 10 to oscillate. For example, the oscillation circuit 30 generates an oscillation signal by causing the oscillator 10 to oscillate. The oscillation signal is, for example, an oscillation clock signal. For example, the oscillation circuit 30 can be implemented using an oscillation drive circuit electrically connected to one end and the other end of the oscillator 10, as well as passive components such as capacitors and resistors. The drive circuit can be implemented, for example, using a CMOS inverter circuit or a bipolar transistor. The drive circuit is the core circuit of the oscillation circuit 30, and it drives the oscillator 10 with voltage or current, thereby causing the oscillator 10 to oscillate. As the oscillation circuit 30, various types of oscillation circuits, such as inverter type, Pierce type, Colpitts type, or Hartley type, can be used. In addition, the connection in this embodiment is an electrical connection. An electrical connection is a connection that can transmit electrical signals, and it is a connection that can transmit information based on electrical signals. The electrical connection can also be a connection via passive components, etc.

[0038] The temperature detection circuit 50 is a sensor circuit for detecting temperature. Specifically, the temperature detection circuit 50 outputs a temperature-dependent voltage, VTS, which varies according to the ambient temperature. For example, the temperature detection circuit 50 generates the temperature detection voltage VTS as a temperature detection signal using temperature-dependent circuit elements. Specifically, the temperature detection circuit 50 outputs a temperature detection voltage VTS that varies with temperature, for example, by utilizing the temperature dependence of the forward voltage of a PN junction. Alternatively, a variation of the temperature detection circuit 50 can be implemented using a digital temperature detection circuit. In this case, the temperature detection voltage VTS is generated by performing a D / A conversion on the temperature detection data.

[0039] The temperature compensation circuit 40 performs temperature compensation for the oscillation frequency of the oscillation circuit 30. For example, based on the temperature detection voltage VTS from the temperature detection circuit 50, the temperature compensation circuit 40 outputs a temperature compensation voltage VCP for the oscillation frequency of the oscillation signal to the oscillation circuit 30. Temperature compensation is, for example, a process that compensates for fluctuations in the oscillation frequency caused by temperature variations. That is, the temperature compensation circuit 40 performs temperature compensation for the oscillation frequency of the oscillation circuit 30 so that the oscillation frequency remains constant even in the presence of temperature variations. Alternatively, a variation can be implemented where the temperature compensation data obtained by A / D conversion of the temperature compensation voltage VCP is used to digitally adjust the oscillation frequency in the variable capacitor circuit of the oscillation circuit 30.

[0040] Furthermore, the temperature compensation circuit 40 has an operational amplifier OPD, which outputs a temperature compensation voltage VCP. For example, as described later, the temperature compensation circuit 40 includes a current-to-voltage conversion circuit that converts the temperature compensation current into a temperature compensation voltage VCP, and the operational amplifier OPD disposed in the current-to-voltage conversion circuit outputs the temperature compensation voltage VCP.

[0041] A reference voltage generation circuit 60 for temperature compensation generates a reference voltage VRC for temperature compensation. The generated reference voltage VRC is then output to a temperature compensation circuit 40. The temperature compensation circuit 40 generates a temperature compensation voltage VCP based on temperature compensation using this reference voltage VRC. For example, the temperature compensation voltage VCP is set to become the reference voltage VRC at its inflection point temperature. Furthermore, the temperature compensation voltage VCP varies relative to the reference voltage VRC, for example, varying towards the positive or negative side relative to the reference voltage VRC. The inflection point temperature is, for example, a typical temperature, such as -25°C. For example, the higher-order temperature compensation current generated by the temperature compensation circuit 40 is set to be, for example, 0 at the inflection point temperature.

[0042] Furthermore, in this embodiment, the input limit voltage PINLM of the first input terminal of the operational amplifier OPD of the temperature compensation circuit 40 has a temperature characteristic that is a first polarity, either positive or negative. Figure 1 In this circuit, the first input terminal of the operational amplifier OPD is, for example, a non-inverting input terminal, and the input limit voltage PINLM of this non-inverting input terminal has a temperature characteristic with a first polarity. In this case, the input limit voltage of the inverting input terminal, which is the second input terminal of the operational amplifier OPD, can also have a temperature characteristic with a first polarity. The input limit voltage is either the lower input limit voltage or the upper input limit voltage. Furthermore, the reference voltage VRC input to the first input terminal of the operational amplifier OPD also has a temperature characteristic with the same first polarity as the temperature characteristic of the input limit voltage PINLM. That is, when the input limit voltage PINLM of the first input terminal of the operational amplifier OPD in the temperature compensation circuit 40 has a temperature characteristic with a first polarity that is either positive or negative, the reference voltage generation circuit 60 outputs a reference voltage VRC with the same first polarity as the input limit voltage PINLM to the first input terminal of the operational amplifier OPD.

[0043] For example, the reference voltage VRC input to the first input terminal of the operational amplifier OPD is input to the transistor of the differential pair of the operational amplifier OPD. If the transistor of the differential pair is a bipolar transistor, the reference voltage VRC is input to the base of the bipolar transistor. If the transistor of the differential pair is a MOS transistor, the reference voltage VRC is input to the gate of the MOS transistor. Therefore, the input limit voltage PINLM of the first input terminal of the operational amplifier OPD has a temperature characteristic that is either positive or negative. For example, if the transistor of the differential pair is an npn bipolar transistor or an N-type MOS transistor, the lower input limit voltage of PINLM, for example, has a negative temperature characteristic. Furthermore, if the transistor of the differential pair is a pnp bipolar transistor or a P-type MOS transistor, the upper input limit voltage of PINLM, for example, has a positive temperature characteristic.

[0044] Therefore, when a reference voltage VRC, which is constant relative to temperature changes, is input to the first input terminal of the operational amplifier OPD, the output voltage range of the operational amplifier OPD narrows when the power supply voltage of the circuit device 20 is reduced. Consequently, when the power supply voltage is reduced, the voltage range of the temperature compensation voltage VCP output by the operational amplifier OPD of the temperature compensation circuit 40 narrows, making it difficult to perform proper temperature compensation.

[0045] In this embodiment, the temperature characteristic of the input limit voltage PINLM at the first input terminal of the operational amplifier OPD has the same first polarity as the temperature characteristic of the reference voltage VRC. For example, if the transistor in the differential pair is an npn bipolar transistor or an N-type MOS transistor, the lower input limit voltage of the input limit voltage PINLM has a negative temperature characteristic. In this case, the reference voltage generation circuit 60 outputs a reference voltage VRC with a negative temperature characteristic, which has the same polarity as the temperature characteristic of the lower input limit voltage. Alternatively, if the transistor in the differential pair is a pnp bipolar transistor or a P-type MOS transistor, the upper input limit voltage of the input limit voltage PINLM has a positive temperature characteristic. In this case, the reference voltage generation circuit 60 outputs a reference voltage VRC with a positive temperature characteristic, which has the same polarity as the temperature characteristic of the upper input limit voltage. Thus, when the input limit voltage PINLM decreases with temperature changes, the reference voltage VRC also decreases; when the input limit voltage PINLM increases with temperature changes, the reference voltage VRC also increases. The input limit voltage PINLM and the reference voltage VRC change with the same polarity of temperature characteristic relative to temperature changes. Therefore, even when the power supply voltage of the circuit device 20 is reduced to a low voltage, the output voltage range of the operational amplifier OPD of the temperature compensation circuit 40 can be suppressed from narrowing, and the temperature compensation voltage VCP can be output over a wider voltage range, thus achieving appropriate temperature compensation.

[0046] Figure 2 A detailed structural example of the circuit device 20 and oscillator 4 in this embodiment is shown. Figure 2 In the circuit device 20, in addition to the oscillation circuit 30, temperature compensation circuit 40, and reference voltage generation circuit 60, it also includes a temperature detection circuit 50, an output circuit 80, a power supply circuit 90, a control circuit 100, and a non-volatile memory 110. Furthermore, the oscillator 4 includes a vibrator 10 and the circuit device 20, with the vibrator 10 electrically connected to the circuit device 20. For example, the vibrator 10 and the circuit device 20 are electrically connected using internal wiring, bonding wires, or metal bumps in a package that houses the vibrator 10 and the circuit device 20. Moreover, the circuit device 20 and the oscillator 4 are not limited to... Figure 2 The structure can be transformed in various ways, such as omitting some of its constituent elements, adding other constituent elements, or replacing some of its constituent elements with other constituent elements.

[0047] Furthermore, the circuit device 20 includes pads PVDD, PGND, PX1, PX2, and PCK. The pads are terminals of the circuit device 20, which serves as a semiconductor chip. For example, in the pad region, a metal layer is exposed from a passivation film that serves as an insulating layer, and this exposed metal layer constitutes the pads serving as terminals of the circuit device 20. Pads PVDD and PGND are power pads and ground pads, respectively. The power supply voltage VDD from an external power supply device is supplied to pad PVDD. Pad PGND is a pad supplied as ground voltage GND. Ground voltage is, for example, ground potential. In this embodiment, GND is appropriately referred to as VSS. For example, VDD corresponds to the high-potential side power supply, and VSS as GND corresponds to the low-potential side power supply. Pads PX1 and PX2 are pads for connecting the oscillator 10. Pad PCK is a pad for outputting the clock signal CK. Pads PVDD, PGND, and PCK are electrically connected to terminals TVDD, TGND, and TCK, which are external terminals for external connection to the oscillator 4. For example, these pads and terminals are electrically connected using internal wiring, bonding wires, or metal bumps within the package. Alternatively, terminals and pads can be provided to receive an external control voltage, which allows an external system to control the oscillation frequency.

[0048] The oscillation circuit 30 is electrically connected to the oscillator 10 via pads PX1 and PX2. Pads PX1 and PX2 are pads for connecting the oscillator. The oscillation drive circuit of the oscillation circuit 30 is disposed between pads PX1 and PX2. The oscillation circuit 30 includes a variable capacitor circuit 32. The variable capacitor circuit 32 is, for example, a circuit that changes the capacitance of at least one of the ends of the oscillator 10, and the oscillation frequency of the oscillation circuit 30 can be adjusted by adjusting the capacitance of the variable capacitor circuit 32. That is, by electrically connecting the variable capacitor circuit 32 to at least one of pads PX1 and PX2, the load capacitance of the oscillation circuit 30 can be variably adjusted. The variable capacitor circuit 32 can be implemented, for example, by a variable capacitor element such as a varactor diode. For example, the variable capacitor circuit 32 is composed of at least one variable capacitor element.

[0049] The temperature compensation circuit 40 performs analog temperature compensation, for example, based on a polynomial approximation. For instance, when approximating the temperature compensation voltage VCP of the frequency-temperature characteristics of the compensation oscillator 10 using a polynomial, the temperature compensation circuit 40 performs analog temperature compensation based on the coefficient information of the polynomial. Analog temperature compensation is achieved, for example, through the addition of current or voltage signals, which are analog signals. For example, when approximating the temperature compensation voltage VCP using a high-order polynomial, the 0th, 1st, and higher-order coefficients of the polynomial are stored as 0th-order correction data, 1st-order correction data, and higher-order correction data, respectively, in a storage unit implemented, for example, a non-volatile memory 110. Higher-order coefficients are, for example, coefficients of orders greater than 1st, and higher-order correction data are correction data corresponding to the higher-order coefficients. For example, when approximating the temperature compensation voltage VCP using a 3rd-order polynomial, the 0th, 1st, 2nd, and 3rd-order coefficients of the polynomial are stored as 0th-order correction data, 1st-order correction data, 2nd-order correction data, and 3rd-order correction data, respectively, in the storage unit. Then, the temperature compensation circuit 40 performs temperature compensation based on the 0th to 3rd order correction data. In this case, the 2nd order correction data or temperature compensation based on the 2nd order correction data may also be omitted. Furthermore, for example, when approximating the temperature compensation voltage VCP using a 5th order polynomial, the 0th, 1st, 2nd, 3rd, 4th, and 5th order coefficients of the polynomial are stored in the storage unit as 0th order correction data, 1st order correction data, 2nd order correction data, 3rd order correction data, 4th order correction data, and 5th order correction data. Then, the temperature compensation circuit 40 performs temperature compensation based on the 0th to 5th order correction data. In this case, the 2nd or 4th order correction data or temperature compensation based on the 2nd or 4th order correction data may also be omitted. Additionally, the degree of the polynomial approximation is arbitrary; for example, a polynomial approximation with a degree greater than 5 may be performed.

[0050] The power supply circuit 90 is supplied with, for example, an external power supply voltage VDD and a ground voltage GND, to supply various power supply voltages for the internal circuits of the circuit device 20. For example, the power supply circuit 90 is supplied with a power supply voltage VDD from the pad PVDD and a ground voltage VSS from the pad PGND as GND, to supply various power supply voltages for the internal circuits of the circuit device 20. For example, the power supply circuit 90 supplies various circuits of the circuit device 20, such as the power supply voltage isotropic oscillation circuit 30, the temperature compensation circuit 40, and the temperature detection circuit 50, which are obtained by regulating the power supply voltage.

[0051] The control circuit 100 is a circuit that performs various control processes, such as those implemented by logic circuits. For example, the control circuit 100 controls the circuit device 20 as a whole, or controls the sequence of actions of the circuit device 20. Furthermore, the control circuit 100 performs various processes for controlling the oscillation circuit 30, or controls the temperature compensation circuit 40, temperature detection circuit 50, reference voltage generation circuit 60, output circuit 80, or power supply circuit 90, or controls the reading and writing of information from the non-volatile memory 110. The control circuit 100 can be implemented, for example, using an ASIC (Application Specific Integrated Circuit) circuit based on automatic configuration routing such as a gate array.

[0052] The non-volatile memory 110 is a memory that retains information even when no power is supplied. For example, the non-volatile memory 110 is a memory that can retain information and rewrite information even when no power is supplied. The non-volatile memory 110 stores various information required for the operation of the circuit device 20. The non-volatile memory 110 can be implemented using EEPROM (Electrically Erasable Programmable Read-Only Memory), which is implemented using FAMOS (Floating Gate Avalanche Injection MOS memory) or MONOS (Metal-Oxide-Nitride-Oxide-Silicon memory). Furthermore, the non-volatile memory 110 stores correction data such as primary correction data and higher-order correction data for temperature compensation of the temperature compensation circuit 40.

[0053] The output circuit 80 outputs a clock signal CK based on the oscillation signal from the oscillation circuit 30. For example, the output circuit 80 buffers the oscillation signal, which is the oscillation clock signal from the oscillation circuit 30, and outputs it as the clock signal CK to the pad PCK. Then, the clock signal CK is output to the outside via the clock output terminal TCK of the oscillator 4. For example, the output circuit 80 outputs the clock signal CK in the form of a single-ended CMOS signal. Alternatively, the output circuit 80 may output the clock signal CK in a signal form other than CMOS. Alternatively, a clock signal generation circuit, such as a PLL circuit, may be provided after the oscillation circuit 30. This clock signal generation circuit generates a clock signal CK with a frequency obtained by multiplying the frequency of the oscillation signal, and the output circuit 80 buffers the clock signal CK generated by this clock signal generation circuit and outputs it.

[0054] The reference voltage generation circuit 60 for temperature compensation generates a reference voltage VRC for temperature compensation and outputs it to the temperature compensation circuit 40. For example, the reference voltage generation circuit 60 has a reference circuit that generates a voltage VRF, such as the BGR voltage. BGR is an abbreviation for bandgap reference. Furthermore, the reference voltage generation circuit 60 generates the reference voltage VRC based on the voltage VRF generated by the reference circuit. In this case, the reference voltage generation circuit 60 may also have a regulator that generates the reference voltage VRC based on the voltage generated by the regulator based on the voltage VRF. For example, the regulator adjusts the power supply voltage VDD based on the voltage VRF, and the reference voltage generation circuit 60 generates the reference voltage VRC based on the voltage generated by the regulator. For example, the reference voltage generation circuit 60 uses the voltage VRF generated by the reference circuit or the voltage generated by the regulator based on the voltage VRF as the reference power supply voltage to generate the reference voltage VRC. For example, the reference voltage generation circuit 60 divides the reference power supply voltage using a voltage generation circuit composed of resistor circuits, etc., thereby generating the reference voltage VRC. In this case, multiple reference voltages can also be generated by making the resistor division ratios in the voltage generation circuit different, and supplied to the temperature compensation circuit 40.

[0055] Furthermore, in this application, the input limit voltage PINLM of the first input terminal of the operational amplifier OPD of the temperature compensation circuit 40 has a temperature characteristic of first polarity, and the reference voltage VRC input to the first input terminal of the operational amplifier OPD also has a temperature characteristic of first polarity. That is, the reference voltage generation circuit 60 generates a reference voltage VRC with positive or negative temperature characteristics, rather than a reference voltage VRC with flat temperature characteristics, and outputs it to the temperature compensation circuit 40. In this case, at the inflection point temperature of the temperature compensation voltage VCP, the temperature compensation voltage VCP becomes the reference voltage VRC.

[0056] Figure 3 An example of the structure of the temperature compensation circuit 40 is shown. However, the temperature compensation circuit 40 is not limited to... Figure 3 The structure can be transformed in various ways, such as omitting some of its constituent elements, adding other constituent elements, or replacing some of its constituent elements with other constituent elements.

[0057] The temperature compensation circuit 40 is a circuit that outputs a temperature compensation voltage VCP by using a polynomial approximation with temperature as the variable. This temperature compensation circuit 40 includes a current generation circuit 42 and a current-to-voltage conversion circuit 46. The current generation circuit 42 generates a temperature compensation current ICP based on the temperature detection result from the temperature detection circuit 50. For example, the current generation circuit 42 generates a temperature compensation current ICP for temperature compensation of the frequency-temperature characteristics of the oscillator 10 based on the temperature detection voltage VTS, which is the temperature detection result. The temperature compensation current ICP is also referred to as the function current. Then, the current-to-voltage conversion circuit 46 converts the temperature compensation current ICP from the current generation circuit 42 into a voltage and outputs the temperature compensation voltage VCP. Specifically, the current-to-voltage conversion circuit 46 outputs the temperature compensation voltage VCP through the operational amplifier OPD1.

[0058] The current generation circuit 42 includes a first-order correction circuit 43 and a higher-order correction circuit 44. The first-order correction circuit 43 and the higher-order correction circuit 44 are also referred to as the first-order compensation circuit and the higher-order compensation circuit, respectively. The first-order correction circuit 43 outputs a first-order current, which is an approximate first-order function, based on the temperature detection voltage VTS. For example, the first-order correction circuit 43 outputs a first-order current based on the first-order correction data corresponding to the first-order coefficients of the polynomial in the polynomial approximation. The higher-order correction circuit 44 outputs a higher-order current ICU, which is an approximate higher-order function, to the current-to-voltage conversion circuit 46 based on the temperature detection voltage VTS. For example, the higher-order correction circuit 44 outputs a higher-order current ICU based on the higher-order correction data corresponding to the higher-order coefficients of the polynomial in the polynomial approximation. The current obtained by adding the higher-order current ICU to the first-order current of the first-order correction circuit 43 is used as the temperature compensation current ICP and input to the current-to-voltage conversion circuit 46.

[0059] like Figure 3 As shown, the primary calibration circuit 43 includes operational amplifier OPD2 and resistors RD1 and RD2. Additionally, the primary calibration circuit 43 may include a resistor RD3 with a variable resistance value. The reference voltage VRC is input to the non-inverting input terminal of operational amplifier OPD2. Resistor RD1 is positioned between node ND1, the input node of the temperature sensing voltage VTS, and node ND2, the inverting input terminal of operational amplifier OPD2. Resistor RD2 is positioned between node ND2 and node ND3, the output terminal of operational amplifier OPD2. Resistor RD3 is positioned between node ND3 and node ND4, the output node of current generation circuit 42.

[0060] The current-to-voltage conversion circuit 46 outputs a temperature-compensated voltage VCP by performing current-to-voltage conversion on the temperature-compensated current ICP, which is the sum of the first-order current and the higher-order current ICU. This generates a temperature-compensated voltage VCP that approximates a polynomial function. Specifically, the current-to-voltage conversion circuit 46 includes an operational amplifier OPD1 and a feedback resistor RD. The reference voltage VRC is input to the non-inverting input terminal of the operational amplifier OPD1, and the output node ND4 of the current generation circuit 42 is connected to the inverting input terminal. The resistor RD is placed between the output terminal and the inverting input terminal of the operational amplifier OPD1. Furthermore, in Figure 3 In this configuration, the phase compensation capacitor CD is placed between the output terminal and the inverting input terminal of the operational amplifier OPD1, but it can also be configured without the capacitor CD.

[0061] so, Figure 3 The temperature compensation circuit 40 includes a primary correction circuit 43 and a higher-order correction circuit 44 that receive the input temperature detection voltage VTS. It also includes a current generation circuit 42 that generates a temperature compensation current ICP through the primary and higher-order correction circuits 43 and 44, and a current-to-voltage conversion circuit 46 that converts the temperature compensation current ICP into a voltage and outputs a temperature compensation voltage VCP. With this configuration, the temperature compensation current ICP, generated by the current generation circuit 42 based on the temperature detection voltage VTS, can be converted into a voltage and output as the temperature compensation voltage VCP by the current-to-voltage conversion circuit 46.

[0062] Figure 4 This is an explanatory diagram regarding temperature compensation. The 0th, 1st, 2nd, 3rd, 4th, and 5th order components represent the characteristics of these components as 0th, 1st, 2nd, 3rd, 4th, and 5th order functions relative to temperature, respectively. Then, through... Figure 3 The primary correction circuit 43 performs temperature compensation for the primary component, and the higher-order correction circuit 44 performs temperature compensation for the secondary, tertiary, quaternary, and quinary components. Alternatively, the corrections for the secondary and quaternary components can be omitted. Based on... Figure 4 The temperature compensation voltage VCP generated by such temperature compensation causes a change in the capacitance of the variable capacitor circuit 32, thereby eliminating the temperature-induced fluctuations in the oscillation frequency of the oscillator 10 and making the oscillation frequency constant relative to temperature changes. In this case, the temperature characteristics of the oscillation frequency of the oscillator 10 cause process deviations. Therefore, at the time of product shipment, the clock frequency of the oscillator 4 is monitored, and appropriate correction data based on the monitoring results is written into the non-volatile memory 110 of the circuit device 20 for temperature compensation based on this correction data.

[0063] Figure 5 This is an example of the structure of the oscillator circuit 30. Furthermore, the oscillator circuit 30 is not limited to... Figure 5 The structure can be transformed in various ways, such as omitting some of its constituent elements, adding other constituent elements, or replacing some of its constituent elements with other constituent elements.

[0064] Figure 5 The oscillation circuit 30 includes a bipolar transistor TR for driving the oscillator 10, a current source IS for supplying current to the bipolar transistor TR, and a variable capacitor circuit 32. Furthermore, node NX at one end of the oscillator 10 is connected to the base of the bipolar transistor TR, and node NY at the other end of the oscillator 10 is connected to the collector of the bipolar transistor TR. In addition, the variable capacitor circuit 32 includes variable capacitor elements CX and CY. The variable capacitor element CX is disposed between node NX and node VSS, and the variable capacitor element CY is disposed between node NY and node VSS. The variable capacitor elements CX and CY are implemented, for example, by varactor diodes.

[0065] In this case, the variable capacitor circuit 32 is a circuit whose capacitance change characteristic relative to the capacitor control voltage is, for example, positive. A positive capacitance change characteristic means that the capacitance increases as the capacitor control voltage increases. Alternatively, the capacitance change characteristic of the variable capacitor circuit 32 can also be negative. Furthermore, the temperature compensation circuit 40 supplies the temperature compensation voltage VCP as the capacitor control voltage to the variable capacitor circuit 32. Since the variable capacitor circuit 32 is a positive characteristic variable capacitor circuit, when the temperature compensation voltage VCP from the temperature compensation circuit 40 increases, the capacitance of the variable capacitor circuit 32 increases, and the oscillation frequency of the oscillation circuit 30 decreases. Thus, temperature compensation can be achieved to offset the increase in oscillation frequency. Furthermore, when the temperature compensation voltage VCP from the temperature compensation circuit 40 decreases, the capacitance of the variable capacitor circuit 32 decreases, and the oscillation frequency of the oscillation circuit 30 increases. Thus, temperature compensation can be achieved to offset the decrease in oscillation frequency. Alternatively, a variable capacitor circuit that controls the capacitance by an externally input frequency control voltage can be provided in the oscillation circuit 30, allowing the oscillation frequency to be variably controlled by this frequency control voltage.

[0066] Figure 6 This is an example of the structure of the function current generation circuit 140 included in the temperature compensation circuit 40. This function current generation circuit 140 is, for example, provided in... Figure 3 The higher-order correction circuit 44 generates higher-order function currents such as the 2nd, 3rd, 4th, and 5th orders.

[0067] like Figure 6As shown, the function current generation circuit 140 includes a reference current generation circuit 141, a first compensation circuit 151, and a second compensation circuit 152. The reference current generation circuit 141 generates a reference current IR. The first compensation circuit 151 performs temperature compensation within a temperature range that is the low-temperature side of a first temperature range, and the second compensation circuit 152 performs temperature compensation within a temperature range that is the high-temperature side of a second temperature range.

[0068] The first compensation circuit 151 and the second compensation circuit 152 each include multiple differential pair circuits. Reference currents IRF1 and IRF2, mirrored from the reference current IR, flow through each differential pair circuit of the first compensation circuit 151. Reference currents IRG1 and IRG2, mirrored from the reference current IR, also flow through each differential pair circuit of the second compensation circuit 152. Furthermore, each differential pair circuit includes a first bipolar transistor and a second bipolar transistor, which are also differential pairs. A temperature detection voltage VTS is input to the base of the first bipolar transistor, and any one of VL1, VL2, VH1, and VH2, serving as a reference voltage, is input to the base of the second bipolar transistor. These reference voltages are also generated by the reference voltage generation circuit 60.

[0069] In addition, Figure 6 The diagram shows a case where each compensation circuit in the first compensation circuit 151 and the second compensation circuit 152 includes two differential pair circuits, but the number of differential pair circuits included in each compensation circuit is not limited to this; the number of differential pair circuits can also be three or more. Furthermore, in Figure 6 In the case of this structure, the polarity of the temperature characteristic of the temperature detection voltage VTS used in the first compensation circuit 151 on the low-temperature side is set to be different from the polarity of the temperature characteristic of the temperature detection voltage VTS used in the second compensation circuit 152 on the high-temperature side. For example, if a temperature detection voltage VTS with a negative temperature characteristic is used in the first compensation circuit 151 on the low-temperature side, a temperature detection voltage VTS with a positive temperature characteristic can be used in the second compensation circuit 152 on the high-temperature side.

[0070] Then, the first compensation circuit 151 generates a temperature compensation current IF = IF1 + IF2 within the low-temperature side, and the second compensation circuit 152 generates a temperature compensation current IG = IG1 + IG2 within the high-temperature side. Furthermore, since the reference current IR is a constant current, the reference currents IRF1 = IF1 + IL1 and IRF2 = IF2 + IL2 flowing through each differential pair circuit of the first compensation circuit 151 also become constant currents with constant values. Similarly, the reference currents IRG1 = IG1 + IH1 and IRG2 = IG2 + IH2 flowing through each differential pair circuit of the second compensation circuit 152 also become constant currents with constant values.

[0071] Furthermore, within the low-temperature range, the current IF = IF1 + IF2 increases, while the current IG = IG1 + IG2 decreases. Conversely, within the high-temperature range, the current IG = IG1 + IG2 increases, while the current IF = IF1 + IF2 decreases. By using such a function current generation circuit 140, such as... Figure 7 As shown, it can generate function currents of higher orders such as 2nd, 3rd, 4th, and 5th. For example, the current IF flowing to the first compensation circuit 151 within the temperature range of the low-temperature side is set to... Figure 7 The characteristic shown in K1 is such that the current IG flowing to the second compensation circuit 152 within the high-temperature side is set to the characteristic shown in K2. Therefore, a quadratic function current as shown in K3 can be generated. Furthermore, the current IF flowing to the first compensation circuit 151 within the low-temperature side is set to... Figure 7 The characteristic shown in K4 sets the current IG flowing to the second compensation circuit 152 within the temperature range of the high-temperature side to the characteristic shown in K5. Thus, a third-order function current as shown in K6 can be generated. Fourth-order and fifth-order function currents can also be generated in the same way.

[0072] 2. Temperature characteristics of input limiting voltage and reference voltage

[0073] In recent years, there has been a demand for lower power supply voltage VDD. By lowering the power supply voltage VDD, it is possible to achieve lower power consumption in circuit device 20, oscillator 4, and so on. However, it has been found that as the power supply voltage VDD decreases, it becomes difficult to ensure the output voltage range of temperature compensation circuit 40.

[0074] For example, Figure 8 An example of the structure of the amplifier circuit included in the temperature compensation circuit 40 is shown. This amplifier circuit is an inverting amplifier circuit, comprising an operational amplifier OPD that operates powered by a supply voltage VDL and resistors RS and RF. The operational amplifier OPD, for example, corresponds to... Figure 3 The operational amplifier OPD1, resistors RS and RF correspond to Figure 3 Resistors RD3 and RD are used. Furthermore, resistors RS and RF are connected in series between the input terminal of voltage VIN and the output terminal of operational amplifier OPD. Additionally, the reference voltage VRC is input to the non-inverting input terminal of operational amplifier OPD, the connection point NSF of resistors RS and RF is connected to the inverting input terminal, and the output voltage VQ is output from the output terminal. The non-inverting input terminal is the first input terminal, and the inverting input terminal is the second input terminal. Moreover, Figure 8 The output voltage VQ of the amplifier circuit is shown in equation (1). Furthermore, in this embodiment, the same reference numerals are used to represent resistors and their resistance values. For example, the resistance values ​​of resistors RS and RF are also denoted as RS and RF.

[0075]

Mathematical Formula 1

[0076] Figure 9 This shows an example of the structure of an operational amplifier (OPD). Figure 9 The differential section of the operational amplifier (OPD) includes: transistors TB1 and TB2 forming a current mirror circuit; bipolar transistors TB3 and TB4 serving as a differential pair; and transistor TB5 serving as a current source. P-type transistors TB1 and TB2 are located between nodes VDL and nodes NB1 and NB2, with their gates connected to node NB1. An npn bipolar transistor TB3 is located between nodes NB1 and NB3, with its base receiving a voltage NIN from the inverting input terminal. An npn bipolar transistor TB4 is located between nodes NB2 and NB3, with its base receiving a voltage PIN from the non-inverting input terminal. Alternatively, a variation using an N-type MOS transistor can be implemented instead of npn bipolar transistors TB3 and TB4. An N-type transistor TB5 is located between nodes NB3 and VSS, with its gate receiving a bias voltage VBS.

[0077] Furthermore, the output section of the operational amplifier OPD includes transistors TB6 and TB7 connected in series between nodes VDL and VSS. The gate of the P-type transistor TB6 is connected to node NB2, which serves as the output node for the differential section, and the gate of the N-type transistor TB7 is biased by the input voltage VBS. The output voltage VQ is output from node NB4, between transistors TB6 and TB7. Capacitor CB is used for phase compensation.

[0078] Here, will Figure 9 The base-emitter voltages of bipolar transistors TB3 and TB4 are set to VBE. The overdrive voltage of N-type transistor TB5 is set to VOVN. Furthermore, the lower input limit voltage of the first input terminal of operational amplifier OPD is set to PINMIN, and the lower input limit voltage of the second input terminal of operational amplifier OPD is set to NINMIN. The first input terminal of operational amplifier OPD corresponds to the base of bipolar transistor TB4, and the second input terminal corresponds to the base of bipolar transistor TB3. Therefore, the following equation (2) holds true regarding the lower input limit voltages PINMIN and NINMIN.

[0079]

Mathematical Formula 2

[0080] The above equation (2) is valid, which ensures that bipolar transistors TB3 and TB4 operate in the active region and transistor TB5 operates in the saturation region.

[0081] Furthermore, the overdrive voltage of the P-type transistor TB6 is set to VOVP, and the maximum voltage of the output voltage VQ of the operational amplifier OPD is set to VQMAX. Thus, the relationship in equation (3) holds true.

[0082]

Mathematical Expression 3

[0083] Therefore, when the power supply voltage VDD of the circuit device 20 decreases, the power supply voltage VDL of the operational amplifier OPD of the temperature compensation circuit 40 decreases, and the maximum voltage VQMAX of the output voltage VQ of the operational amplifier OPD also decreases, thus limiting the output voltage range of the operational amplifier OPD.

[0084] Here, for example, when the threshold voltage of the transistor is set to Vth, the gate-source voltage to VGS, and the drain-source voltage to VDS, the overdrive voltage can be expressed as VOV = VGS - Vth, which is an indicator of the extent to which VGS exceeds Vth. For the transistor to operate in the saturation region, VDS > VOV. The overdrive voltage VOV (VOVN, VOVP) of the transistor operating in the saturation region is, for example, around 0.1V to 0.2V.

[0085] And, as Figure 8 As shown, a reference voltage VRC is input to the first input terminal of the operational amplifier OPD. At this time, through virtual grounding, the voltage at the second input terminal of the operational amplifier OPD also becomes the same voltage as VRC. Therefore, in order for the operational amplifier OPD to work properly, the reference voltage VRC input to the first input terminal needs to be a voltage above the lower input limit voltage PINMIN, which requires the following relationship (4) to hold.

[0086]

Mathematical Expression 4

[0087] also, Figure 4 The temperature compensation voltage VCP described herein is a voltage that varies with the reference voltage VRC towards the positive or negative side based on temperature changes. The voltage variation from the reference voltage VRC towards the positive side is approximately equal to the voltage variation towards the negative side. Therefore, the voltage range of the temperature compensation voltage VCP can be expressed as follows (5).

[0088]

Mathematical Expression 5

[0089] For example, suppose the operating temperature range specified by the circuit device 20 and oscillator 4 is, for example, -40°C to 105°C. In this case, VBE, which is the base-emitter voltage of bipolar transistors TB4 and TB3, is, for example, about 0.4V at a typical temperature of 25°C. Furthermore, VBE is, for example, about 0.6V at -40°C, the lower limit of the operating temperature range, and about 0.3V at 105°C, the upper limit of the operating temperature range. That is, VBE, as the base-emitter voltage, has a negative temperature characteristic. The operating temperature range is a temperature-compensated temperature range. Furthermore, while the operating temperature range is set to -40°C to 105°C here as an example, it is not limited to this; for example, it could be -40°C to 125°C or 0°C to 85°C, etc.

[0090] For example, the overdrive voltage of transistor TB5 is set to VOVN = 0.1V. Therefore, according to equation (2) above, PINMIN and NINMIN, which are the lower input limit voltages, become 0.4 + 0.1 = 0.5V at typical temperatures, 0.6 + 0.1 = 0.7V at the lower limit temperature of the operating temperature range, and 0.3 + 0.1 = 0.4V at the upper limit temperature. Furthermore, according to equation (4) above, the reference voltage VRC input to the first input terminal of operational amplifier OPD needs to be a voltage greater than or equal to PINMIN and NINMIN, which are the lower input limit voltages. Therefore, in order for operational amplifier OPD to operate properly within the operating temperature range, the reference voltage VRC needs to be a voltage greater than or equal to PINMIN = NINMIN = 0.7V, which are the lower input limit voltages at the lower limit temperature of the operating temperature range.

[0091] Furthermore, the power supply voltage VDL of the operational amplifier OPD is, for example, through... Figure 2 The power supply circuit 90 is generated by regulating the power supply voltage VDD supplied from the outside. Moreover, when the power supply voltage VDD is reduced to VDD=1.1V, the power supply voltage of the operational amplifier OPD becomes, for example, VDL=1.0V. Furthermore, when the overdrive voltage of transistor TB6 is VOVP=0.1V, according to the above equation (3), the maximum voltage of the output voltage VQ of the operational amplifier OPD becomes VQMAX=VDL-VOVP=1.0-0.1=0.9V. Therefore, in this case, according to the above equation (5), the voltage range of the temperature compensation voltage VCP becomes VRC±(VQMAX-VRC)=0.7±(0.9-0.7)=0.7±0.2V.

[0092] In this case, if the power supply voltage VDD is high enough, the power supply voltage VDL of the operational amplifier OPD will also increase accordingly, and VQMAX can be increased according to the above equation (3), thus sufficiently expanding the voltage range of the temperature compensation voltage VCP. However, when the power supply voltage VDD is low, as mentioned above, the voltage range of the temperature compensation voltage VCP is as shown in 0.7±0.2V, which is narrower compared to the case where the power supply voltage VDD is high.

[0093] Furthermore, as a method to achieve appropriate temperature compensation even when the voltage range of the temperature compensation voltage VCP becomes narrower as described above, it is considered to make... Figure 5 The method of increasing the capacitance of the variable capacitor elements CX and CY in the variable capacitor circuit 32 to improve the sensitivity KV is described. Sensitivity represents the change in frequency relative to the capacitor control voltage, which serves as the temperature compensation voltage VCP. However, if the sensitivity KV is improved by increasing the capacitance of the variable capacitor elements CX and CY, the deviation and variation of the capacitance of the variable capacitor elements CX and CY become larger, leading to problems such as increased complexity of temperature compensation or increased noise superimposed on the temperature compensation voltage VCP.

[0094] For example, Figure 10 A1 and A2 are examples of the temperature characteristics of the temperature compensation voltage VCP when the power supply voltage is 1.4V. Figure 10 In A1, the sensitivity of the variable capacitor elements CX and CY is set to KV=50 [ppm / V], and the reference voltage is set to VRC=0.85V. Figure 10 In A2, the sensitivity was set to KV = 100 [ppm / V], and the reference voltage was set to VRC = 0.7V. Additionally, Figure 10 B1 represents the maximum temperature compensation voltage VQMAX of VCP when the supply voltage is 1.4V, which becomes VQMAX=1.3V. B2 represents the maximum voltage VQMAX when the supply voltage is 1.0V, which becomes VQMAX=0.9V. In addition, B3 represents the lower limit input voltage PINMIN=NINMIN=0.7V at the lower limit temperature of -40℃.

[0095] When the power supply voltage is high, such as Figure 10 When the maximum voltage VQMAX shown in B1 is high, the voltage range of the temperature compensation voltage VCP can be expanded as shown in A1. However, when the supply voltage is low, such as... Figure 10 As shown in B2, when the maximum voltage VQMAX is low, the voltage range of the temperature compensation voltage VCP narrows, as shown in A2. Therefore, there is a problem that even increasing the sensitivity KV cannot achieve adequate temperature compensation.

[0096] Figure 11This is a schematic diagram of the current-voltage conversion amplifier circuit of the temperature compensation circuit 40. Figure 11 The currents IA and IB correspond to the temperature compensation currents. Furthermore, Figure 11 The output voltage VQ of the current-to-voltage conversion amplifier circuit is shown in equation (6).

[0097]

Mathematical Expression 6

[0098] In the temperature compensation circuit 40, IA and IB, corresponding to the temperature compensation current, are set to 0 when VIN = VRC in equation (6). This ensures that the inflection points in temperature compensation are consistent. That is, as... Figure 6 As explained, in the function current generation circuit 140 of the temperature compensation circuit 40, the first compensation circuit 151 generates a temperature compensation current IF = IF1 + IF2 within the low-temperature side temperature range, and the second compensation circuit 152 generates a temperature compensation current IG = IG1 + IG2 within the high-temperature side temperature range. Furthermore, within the low-temperature side temperature range, the current IF increases, while the current IG decreases to zero. Similarly, within the high-temperature side temperature range, the current IG increases, while the current IF decreases to zero. Moreover, at a typical temperature where VCP = VRC, both currents IG and IF are zero. Figure 11 The currents IA and IB become 0. Therefore, it is possible to make... Figure 7 The inflection points between K1 and K2 are the same as those between K4 and K5.

[0099] Furthermore, in the temperature compensation circuit 40, VIN from the primary correction circuit 43 has a primary temperature characteristic. Therefore, even if the reference voltage VRC has a primary temperature characteristic, as explained in detail later, the primary correction circuit 43 can compensate for the influence of the primary temperature characteristic of the reference voltage VRC.

[0100] Therefore, in this embodiment, when the input limit voltage PINLM of the first input terminal of the operational amplifier OPD has a temperature characteristic with a first polarity, the reference voltage VRC input to the first input terminal also has a temperature characteristic with the same first polarity as the temperature characteristic of the input limit voltage PINLM.

[0101] For example, such as Figure 9As explained in equation (2) above, VBE, which is the base-emitter voltage of the bipolar transistor TB3, has a negative temperature characteristic. Therefore, PINMIN = VBE + VOVN, which is the lower input limit voltage of the first input terminal of the operational amplifier OPD, also has a negative temperature characteristic. For example, the lower input limit voltage PINMIN is 0.7V at -40°C and 0.4V at 105°C, decreasing as the temperature increases. Therefore, the reference voltage VRC input to the first input terminal of the operational amplifier OPD also has the same negative temperature characteristic as the lower input limit voltage PINMIN. That is, normally a constant voltage VRC that does not change with temperature is input to the first input terminal of the operational amplifier OPD, but in this embodiment, a reference voltage VRC with a negative temperature characteristic is instead input to the first input terminal.

[0102] In this way, by inputting a reference voltage VRC with negative temperature characteristics to the first input terminal of the operational amplifier OPD, the output voltage range of the operational amplifier OPD can be expanded, and appropriate temperature compensation can be achieved. Furthermore, as explained in detail later, even when the reference voltage VRC with negative temperature characteristics is input to the first input terminal of the operational amplifier OPD, the primary correction circuit 43 of the temperature compensation circuit 40 can compensate for the negative temperature characteristics of the reference voltage VRC.

[0103] Figure 12 This is an example illustrating the temperature characteristics of the comparative method. For example... Figure 12 As shown in C1, C2, and C3, the temperature characteristic of the temperature compensation voltage VCP varies depending on the process variations. For example, at the factory, the clock frequency of the oscillator 4 is monitored, and correction data based on the monitoring results is written into the non-volatile memory 110. The temperature compensation circuit 40 generates the temperature compensation voltage VCP based on this correction data. Furthermore, in the comparative example, as shown in D1, the reference voltage VRC does not have a negative temperature characteristic; it has a flat temperature characteristic, meaning the reference voltage VRC remains constant with respect to temperature changes. For example, VRC = 0.75V. Also, for example, the power supply voltage is VDD = 1.1V and VDL = 1.0V. Therefore, as shown in D2, VQMAX = VDL - VOVP, which is the maximum voltage of the temperature compensation voltage VCP, becomes 0.9V. Moreover, as shown in D3, PINMIN = VBE + VOVN, which is the lower limit input voltage, has a negative temperature characteristic.

[0104] As explained in equation (4) above, within the operating temperature range used for temperature compensation, the reference voltage VRC needs to be set to a voltage higher than the lower input limit voltage PINMIN. Figure 12As shown in D3, PINMIN has a negative temperature characteristic. Therefore, as shown in D4, VRC is satisfied at the lower limit temperature of the operating temperature range. The reference voltage VRC is set according to the relationship between PINMIN and PINMIN.

[0105] However, in Figure 12 In the comparative method, when the temperature characteristic of the temperature compensation voltage VCP becomes as shown in C2 and C3, for example in D5 and D6, the temperature compensation voltage VCP may exceed the maximum voltage VQMAX. Therefore, it is impossible to expand the voltage range of the temperature compensation voltage VCP, and there is a problem that proper temperature compensation cannot be achieved.

[0106] Figure 13 This is an example illustrating the temperature characteristics of the method in this embodiment. Figure 13 As shown in E1, E2, and E3, the temperature characteristic of the temperature compensation voltage VCP also changes according to process variations. Furthermore, in this embodiment, as shown in F1, the reference voltage VRC has a negative temperature characteristic, decreasing as the temperature increases. Additionally, as shown in F2, the maximum voltage of the temperature compensation voltage VCP, VQMAX = VDL - VOVP, becomes 0.9V.

[0107] In addition, such as Figure 13 As shown in F3, the input lower limit voltage PINMIN, like the reference voltage VRC, has a negative temperature characteristic. However, the slope of the first-order temperature characteristic of the reference voltage VRC is less than the slope of the first-order temperature characteristic of the input lower limit voltage PINMIN. Furthermore, as shown in F4, VRC is designed to satisfy the lower limit temperature within the operating temperature range. The reference voltage VRC is set according to the relationship between PINMIN and PINMIN. Furthermore, when the temperature characteristics of the temperature compensation voltage VCP are as shown in E2 and E3, as shown in F5 and F6, the temperature compensation voltage VCP will not exceed the maximum output voltage VQMAX of the operational amplifier OPD.

[0108] That is, in Figure 12 In the comparative examples, as shown in D1, the reference voltage VRC exhibits a flat temperature characteristic within the operating temperature range. Furthermore, the reference voltage VRC is set to, for example, 0.75V, such that at the lower limit temperature of the operating temperature range shown in D4, the reference voltage VRC exceeds the lower input limit voltage PINMIN. Therefore, at the typical temperature (25°C) shown in D7, the reference voltage VRC also becomes 0.75V, and the temperature compensation voltage VCP becomes a voltage that varies around the reference voltage VRC = 0.75V. Therefore, as in D5 and D6, the temperature compensation voltage VCP may exceed the maximum voltage VQMAX.

[0109] In contrast, Figure 13 In this embodiment, as shown in F1, the reference voltage VRC, like the input lower limit voltage PINMIN, has a negative temperature characteristic. Therefore, at the lower limit temperature shown in F4, when the reference voltage VRC is set above the input lower limit voltage PINMIN, as shown in F7, the reference voltage at a typical temperature is set to VRC = 0.7V. That is, with... Figure 12 Compared to the comparative example, the reference voltage VRC at typical temperatures can be reduced by, for example, by about 50mV. That is, in the comparative example... Figure 12 In this embodiment, the reference voltage VRC in D7 is 0.75V. Figure 13 In F7, the temperature compensation voltage VCP is 0.7V, and its temperature characteristic decreases by 50mV compared to the comparative example. Therefore, in F5 and F6, for example, it is possible to suppress the temperature compensation voltage VCP from exceeding the maximum voltage VQMAX, and appropriate temperature compensation can be achieved compared to the comparative example.

[0110] Figure 14 Other structural examples of operational amplifiers (OPDs) are shown. Figure 9 This is an example of the structure of an operational amplifier OPD with an Nch input stage and a Pch output stage. In contrast, Figure 14 This is an example of the structure of an operational amplifier OPD with a Pch input stage and an Nch output stage. Figure 14 The differential section of the operational amplifier (OPD) includes: transistors TG1 and TG2 forming a current mirror circuit; bipolar transistors TG3 and TG4 serving as a differential pair; and transistor TG5 serving as a current source. N-type transistors TG1 and TG2 are located between nodes NG1 and NG2 and node VSS, with their gates connected to node NG1. PNP bipolar transistor TG3 is located between node NG3 and node NG1, with its base receiving a voltage NIN from the inverting input terminal. PNP bipolar transistor TG4 is located between node NG3 and node NG2, with its base receiving a voltage PIN from the non-inverting input terminal. Alternatively, a variation using a P-type transistor of MOS can be implemented instead of bipolar transistors TG3 and TG4. P-type transistor TG5 is located between node VDL and node NG3, with its gate receiving a bias voltage VBS.

[0111] Furthermore, the output section of the operational amplifier OPD includes transistors TG7 and TG8 connected in series between nodes VDL and VSS. The gate of the N-type transistor TG6 is connected to node NG2, which serves as the output node for the differential section, and the gate of the P-type transistor TG7 is biased by the input voltage VBS. The output voltage VQ is output from node NG4, between transistors TG7 and TG6. Capacitor CG is used for phase compensation.

[0112] Here, will Figure 14 The base-emitter voltage of bipolar transistors TG3 and TG4 is set to VBE. The overdrive voltage of P-type transistor TG5 is set to VOVP. The upper input voltage limit of the first input terminal of operational amplifier OPD is set to PINMAX, and the upper input voltage limit of the second input terminal of operational amplifier OPD is set to NINMAX. The first input terminal of operational amplifier OPD corresponds to the base of bipolar transistor TG4, and the second input terminal corresponds to the base of bipolar transistor TG3. Therefore, the following equation (7) holds true regarding the upper input voltage limits PINMAX and NINMAX.

[0113]

Mathematical Expression 7

[0114] In equation (7) above, VBE, which is the base-emitter voltage, has a negative temperature characteristic, and therefore PINMAX and NINMAX, which are the upper limit voltages of the input, have positive temperature characteristics.

[0115] Furthermore, the overdrive voltage of the N-type transistor TG6 is set to VOVN, and the minimum voltage of the output voltage VQ of the operational amplifier OPD is set to VQMIN. Thus, the relationship in equation (8) holds true.

[0116]

Mathematical Expression 8

[0117] Furthermore, in order for the operational amplifier OPD to work properly, the reference voltage VRC input to the first input terminal needs to be a voltage below the upper input voltage PINMAX, which requires the following relationship (9) to hold.

[0118]

Mathematical Expression 9

[0119] Figure 15 This is an explanation Figure 14 Examples of temperature characteristics of the comparative method in the structure of the operational amplifier (OPD). For example... Figure 15 As shown in G1, G2, and G3, the temperature characteristic of the temperature compensation voltage VCP changes according to process variations. Furthermore, in the comparative example, as shown in H1, the reference voltage VRC exhibits a flat temperature characteristic, for example, set to VRC = 0.3V. Also, as shown in H2, VQMIN = VOVN, the minimum voltage for the temperature compensation voltage VCP, becomes 0.1V. Additionally, as shown in H3, PINMAX = VDL - VBE - VOVP, the upper limit input voltage, has a positive temperature characteristic. Furthermore, the voltage range of the temperature compensation voltage VCP can be expressed as VRC ± (VQMIN - VRC).

[0120] As explained in equation (9) above, the reference voltage VRC needs to be set to a voltage below the upper input voltage PINMAX within the operating temperature range, as shown in H3, where PINMAX has a positive temperature characteristic. Therefore, as shown in H4, this is to ensure that VRC is satisfied at the lower temperature limit. The reference voltage VRC is set according to the relationship between PINMAX. Furthermore, in... Figure 15 In the comparative method, when the temperature characteristic of the temperature compensation voltage VCP becomes the characteristic shown in G3, as shown in H5, the temperature compensation voltage VCP may be lower than the minimum voltage VQMIN.

[0121] Figure 16 This is an explanation Figure 14 An example of the temperature characteristics of the method in this embodiment within the structure of the operational amplifier (OPD). Figure 16 As shown in I1, I2, and I3, the temperature characteristic of the temperature compensation voltage VCP also changes according to process variations. Furthermore, in this embodiment, as shown in J1, the reference voltage VRC has a positive temperature characteristic, increasing with increasing temperature. Additionally, as shown in J2, the minimum voltage VQMIN = VOVN for the temperature compensation voltage VCP becomes 0.1V.

[0122] Furthermore, as shown in J3, the input upper limit voltage PINMAX, like the reference voltage VRC, has a positive temperature characteristic. However, the slope of the first-order temperature characteristic of the reference voltage VRC is less than the slope of the first-order temperature characteristic of the input upper limit voltage PINMAX. Additionally, as shown in J4, VRC is designed to satisfy the lower limit temperature. The reference voltage VRC is set according to the relationship between PINMAX and PINMAX. Furthermore, when the temperature characteristic of the temperature compensation voltage VCP becomes as shown in I3, as shown in J5, the temperature compensation voltage VCP is not lower than the minimum output voltage VQMIN of the operational amplifier OPD.

[0123] That is, in Figure 15 In the comparative example, as shown in H1, the reference voltage VRC has a flat temperature characteristic. The reference voltage VRC is set to, for example, 0.3V, such that at the lower limit temperature shown in H4, the reference voltage VRC is below the upper limit input voltage PINMAX. Therefore, at the typical temperature shown in H6, the reference voltage VRC is also 0.3V, and the temperature compensation voltage VCP becomes a voltage that varies around the reference voltage VRC = 0.3V. Therefore, as shown in H5, the temperature compensation voltage VCP may be lower than the minimum voltage VQMIN.

[0124] In contrast, Figure 16In this embodiment, as shown in J1, the reference voltage VRC, like the input upper limit voltage PINMAX, has a positive temperature characteristic. Therefore, when the reference voltage VRC is set below the input upper limit voltage PINMAX at the lower limit temperature shown in J4, as shown in J6, the reference voltage at a typical temperature becomes VRC = 0.35V. That is, with... Figure 15 Compared to the comparative example, the reference voltage VRC at a typical temperature can be increased by, for example, 50mV. Therefore, in J5, the temperature compensation voltage VCP can be prevented from falling below the minimum voltage VQMIN, and appropriate temperature compensation can be achieved compared to the comparative example.

[0125] 3. Reference voltage generation circuit

[0126] Figure 17 An example of the structure of a reference voltage generation circuit 60 is shown. The reference voltage generation circuit 60 includes a reference circuit 62, a regulator 66, and a voltage generation circuit 68. Furthermore, the reference voltage generation circuit 60 is not limited to... Figure 17 The structure can be modified in various ways, such as omitting some of its components, adding other components, or replacing some components with other components. For example, it is also possible to implement a modification such as not including the regulator 66 and the voltage generation circuit 68 in the reference voltage generation circuit 60.

[0127] Reference circuit 62 generates a voltage VRF as a reference voltage. Voltage VRF is, for example, a voltage with a first polarity and temperature characteristics. Reference voltage generation circuit 60 generates a reference voltage VRC with a first polarity and temperature characteristics based on this voltage VRF. Figure 13 In the case of F1, the first polarity is negative. Figure 16 In the case of J1, the first polarity is positive.

[0128] The regulator 66 generates a voltage VRG as the regulating voltage based on the voltage VRF. For example, the regulator 66 generates the voltage VRG by regulating the power supply voltage VDD of the circuit device 20 based on the voltage VRF.

[0129] Then, the voltage generation circuit 68 generates a reference voltage VRC based on the voltage VRG. For example, the voltage generation circuit 68 uses the voltage VRG as a reference power supply voltage to generate the reference voltage VRC. For example, the voltage generation circuit 68 divides the voltage VRG, which is used as the reference power supply voltage, through a resistor circuit, thereby generating the reference voltage VRC. In this case, the voltage generation circuit 68 can also generate multiple reference voltages with different voltage levels based on the voltage VRG. For example, the voltage generation circuit 68 generates... Figure 3 The higher-order correction circuit 44 possesses various correction circuits, such as the 3rd and 5th order correction circuits. Figure 6The reference voltage used in the function current generation circuit 140. For example, the voltage generation circuit 68 generates a voltage that is similar to the reference voltage used in the function current generation circuit 140. Figure 6 The reference voltages corresponding to voltages VL1, VL2, VH1, and VH2.

[0130] Figure 18 An example of the structure of reference circuit 62 is shown. This reference circuit 62 is a BGR circuit (bandgap reference circuit), more specifically a Widlar-type BGR circuit. Reference circuit 62 includes npn bipolar transistors TA1, TA2, and TA3, resistors R1, R2, and R3, an N-type MOS transistor TA4, P-type MOS transistors TA5 and TA6, and a capacitor CA. Furthermore, reference circuit 62 is not limited to... Figure 18 The structure can be transformed in various ways, such as omitting some of its constituent elements, adding other constituent elements, or replacing some of its constituent elements with other constituent elements.

[0131] Resistors R3 and R1 and bipolar transistor TA1 are connected in series between node NA1 of voltage VRF and node VSS (GND). Furthermore, the base of bipolar transistor TA1 is connected to node NA2 between resistors R3 and R1, the collector is connected to node NA3 at one end of resistor R1, and the emitter is connected to node VSS.

[0132] Furthermore, resistor R2 and bipolar transistor TA2 are connected in series between node NA1 (voltage VRF) and node VSS. The base of bipolar transistor TA2 is connected to node NA3, its collector is connected to node NA4 (one end of resistor R2), and its emitter is connected to node VSS. The base of bipolar transistor TA3 is connected to node NA4, its collector is connected to node NA5, and its emitter is connected to node VSS. Capacitor CA is positioned between nodes NA4 and NA5.

[0133] N-type transistor TA4 is positioned between node VDD and node NA1, with its gate connected to node NA5. P-type transistors TA5 and TA6 form a current mirror circuit, where the current source ISA, connected to the drain of transistor TA6, is mirrored by transistor TA5 and flows to bipolar transistor TA3.

[0134] For example, when the collector current of a bipolar transistor is denoted as IC and the saturation current as IS, the base-emitter voltage is expressed as VBE = (kT / q)·ln(IC / IS) = VT·ln(IC / IS). Here, k is the Boltzmann constant, T is the temperature, and q is the charge of the electron. Furthermore, when the number of bipolar transistors connected in parallel is expressed as Q, the saturation current is expressed as IS = Q·IS0.

[0135] Here, will Figure 18Let the number of bipolar transistors TA1 and TA2 connected in parallel be Q1 and Q2, respectively, and let the collector current IC flowing to bipolar transistors TA1 and TA2 be I1 and I2, respectively. Thus, the base-emitter voltage of bipolar transistor TA1 is expressed as VBE1 = VT·ln{I1 / (Q1·IS0)}, and the base-emitter voltage of bipolar transistor TA2 is expressed as VBE2 = VT·ln{I2 / (Q2·IS0)}. Therefore, if we set ΔVBE = VBE1 - VBE2, it is expressed as ΔVBE = VT·ln{(Q2 / Q1)·(I1 / I2)}.

[0136] Furthermore, the voltage across resistor R1 becomes VBE1-VBE2=ΔVBE, therefore I1=ΔVBE / R1. Thus, the voltage VRF=VBE1+I1·R3 is as shown in equation (10).

[0137]

Mathematical Formula 10

[0138] The first term VBE1 in equation (10) above has a negative temperature characteristic. On the other hand, the second term (R3 / R1)ΔVBE has a positive temperature characteristic. Since VBE1 in the first term is determined as a physical quantity, the negative temperature characteristic of the first term can be eliminated by adjusting the second term. Thus, a voltage VRF with a flat temperature characteristic that minimizes variation within the operating temperature range can be generated. Furthermore, by utilizing the positive temperature characteristic of the second term to offset the negative temperature characteristic of the first term in equation (10) above, the voltage VRF with a flat temperature characteristic becomes approximately 1.25V. That is, by adjusting the voltage VRF to around 1.25V, a voltage VRF with a flat temperature characteristic can be generated. This adjustment of the voltage VRF is performed by adjusting the resistance value of R3 in the second term of equation (10) above. Furthermore, when the adjusted voltage VRF is below 1.25V, VRF has a negative temperature characteristic, and when it exceeds 1.25V, VRF has a positive temperature characteristic.

[0139] Therefore, when the reference voltage generation circuit 60 generates a reference voltage VRC with negative temperature characteristics based on the voltage VRF of the reference circuit 62, the voltage VRF can be adjusted to a voltage lower than 1.25V.

[0140] In addition, Figure 18The reason for including bipolar transistor TA3 is twofold: firstly, to determine the operating point of bipolar transistor TA2, and secondly, to adjust the load current flowing through the load circuit supplied with voltage VRF. Specifically, by including bipolar transistor TA3, the collector-emitter voltage of bipolar transistor TA2 can be prevented from decreasing, allowing bipolar transistor TA2 to operate in the active region. This achieves the first function described above. Furthermore, when the load current IL flows through VRF, the gate voltage of transistor TA4 is adjusted by bipolar transistor TA3, applying feedback to keep voltage VRF constant. This achieves the second function described above. For example, if bipolar transistor TA3 operates in the active region, VBE3, which is the base-emitter voltage of bipolar transistor TA3, becomes constant. Therefore, even if the load current IL changes, the current I2 flowing to bipolar transistor TA2 does not change, and the increase in load current IL flows through transistor TA4.

[0141] For example, if the current flowing through transistor TA4 is set to ITA4, then ITA4 = I1 + I2 + IL. Furthermore, in Figure 18 In the reference circuit 62, when bipolar transistors TA1, TA2, and TA3 are operating in the active region and transistor TA4 is operating in the saturation region, the currents I1 and I2 are uniquely determined, and therefore the voltage VRF becomes constant.

[0142] That is, when the load current IL increases, the gate voltage VG of transistor TA4 increases due to feedback from bipolar transistor TA3, and VG-VRF, which is the gate-source voltage of transistor TA4, also increases. Therefore, the increase in load current IL flows to transistor TA4. Conversely, when the load current IL decreases, the gate voltage VG decreases, and VG-VRF, which is the gate-source voltage, also decreases, thus reducing the current flowing to transistor TA4. Therefore, even if the load current IL changes, the voltage VRF remains constant.

[0143] For example, there are circuits that use operational amplifiers (amplifiers) for feedback control in BGR circuits, but using operational amplifiers increases the noise of the voltage VRF. In contrast, in Figure 18 In the Widlar-type BGR circuit, feedback control is performed without using an operational amplifier, thus generating a low-noise voltage VRF. Furthermore, as mentioned above, even if the load current IL changes, the voltage VRF can be kept constant, achieving low output impedance.

[0144] Figure 19 These are other structural examples of reference circuit 62. Figure 19 It is the reference circuit 62 for PTAT mode. Figure 19Reference circuit 62 includes transistor TC1, resistor RC1, and transistor TC2 connected in series between the nodes of VDD and VSS. Transistor TC1 is a P-type MOS transistor located between the nodes of VDD and NC1, with its gate biased by a voltage VBPT for PTAT. This bias voltage VBPT is controlled by a current source for PTAT (not shown), thereby causing the current IPT of PTAT to flow through resistor RC1. PTAT stands for Proportional To Absolute Temperature, and the current of PTAT increases with temperature. Resistor RC1 is a variable resistor connected in series with transistor TC1 between the nodes of VDD and NC1. The voltage VRF output from the output node NCQ is adjusted by the resistance value of resistor RC1. Transistor TC2 is an N-type MOS transistor with its gate and drain connected to node NC1. That is, the N-type transistor TC2 is connected by a diode.

[0145] exist Figure 19 In the reference circuit 62, when the gate-source voltage of transistor TC2 is set to VGS and the resistance value of resistor RC1 is represented by the same label RC1, a voltage of VRF = VGS + RC1·IPT is output from the output node NCQ.

[0146] Here, the VGS of the diode-connected transistor TC2 becomes the threshold voltage Vth of transistor TC2, therefore VGS = Vth has a negative temperature characteristic. Additionally, the current IPT of PTAT has a positive temperature characteristic. Therefore, by adjusting the resistance value of resistor RC1 using VRF = VGS + RC1·IPT, a voltage VRF with a negative temperature characteristic can be generated, thus generating... Figure 13 The reference voltage VRC, which exhibits a negative temperature characteristic, is shown by F1. Furthermore, [the following is a continuation of the previous sentence, likely related to voltage rating]. Figure 13 The slope of the primary temperature characteristic of the reference voltage VRC shown in F1 is set to be smaller than the slope of the input lower limit voltage PINMIN shown in F3, but this slope setting can also be achieved by adjusting the resistance value of resistor RC1.

[0147] Furthermore, in VRF = VGS + RC1·IPT, by adjusting the resistance value of resistor RC1, a voltage VRF with a positive temperature characteristic can also be generated. Figure 16 The reference voltage VRC has a positive temperature characteristic as shown in J1.

[0148] Figure 20 Other structural examples of reference circuit 62 are shown. Figure 20 and Figure 19 The difference is that, in Figure 20 It is equipped with a bipolar transistor TC3 to replace Figure 19The MOS transistor TC2. The base and collector of the npn bipolar transistor TC3 are connected to node NC1, and the emitter is connected to node VSS. Here, when the base-emitter voltage of the bipolar transistor TC3 is set to VBE, in Figure 20 In this process, the output node NCQ outputs a voltage VRF = VBE + RC1·IPT. Furthermore, since the voltage VBE has a negative temperature characteristic, it is related to... Figure 19 Similarly, by adjusting the resistance value of resistor RC1, it is possible to generate a voltage VRF with a negative temperature characteristic and a reference voltage VRC with a negative temperature characteristic, or to generate a voltage VRF with a positive temperature characteristic and a reference voltage VRC with a positive temperature characteristic.

[0149] Figure 21 Show Figure 17 Example of the structure of regulator 66. Regulator 66 includes operational amplifier OPE, transistor TE and voltage divider circuit 67.

[0150] The non-inverting input terminal of the operational amplifier OPE, serving as the first input terminal, receives the input voltage VRF, while the inverting input terminal, serving as the second input terminal, receives the feedback voltage VFB. The transistor TE is positioned between the first power supply node VDD and the output node NE1 of the voltage VRG, with its gate input to the output of the operational amplifier OPE. Figure 21 In this context, a depletion-mode N-type transistor is used as the transistor TE. However, a P-type transistor can also be used as the transistor TE.

[0151] Voltage divider circuit 67 is disposed between the output node NE1 of voltage VRG and the node VSS, which serves as the second power supply node, to generate a voltage VFB obtained by dividing voltage VRG. For example, voltage divider circuit 67 includes resistors RE1 and RE2 connected in series between the output node NE1 and the node VSS. The feedback voltage VFB from node NE2 between resistors RE1 and RE2 is input to the inverting input terminal of operational amplifier OPE.

[0152] according to Figure 21 The regulator 66 outputs a voltage VRG = {(RE1+RE2) / RE2}VRF. The voltage VRG output by the regulator becomes the voltage at which the regulator... Figure 17 The voltage generation circuit 68 uses a reference power supply voltage. The voltage generation circuit 68 divides the voltage VRG, which serves as the reference power supply voltage, using a resistor circuit and the like, thereby generating a reference voltage VRC.

[0153] As mentioned above, such as Figure 1 , Figure 2As shown, the circuit arrangement 20 of this embodiment includes: an oscillation circuit 30 that oscillates the oscillator 10 to generate an oscillation signal; and a temperature compensation circuit 40 having an operational amplifier OPD that outputs a temperature compensation voltage VCP, the oscillation frequency of the oscillation signal, to the oscillation circuit 30 based on a temperature detection voltage VTS from a temperature detection circuit 50. Furthermore, the circuit arrangement 20 includes a reference voltage generation circuit 60 for temperature compensation that generates a reference voltage VRC for temperature compensation and outputs it to the temperature compensation circuit 40.

[0154] Furthermore, the input limiting voltage PINLM at the first input terminal of the operational amplifier OPD has a temperature characteristic with a first polarity that is either positive or negative. Additionally, the reference voltage VRC input to the first input terminal of the operational amplifier OPD has a temperature characteristic with the same first polarity as the temperature characteristic of the input limiting voltage PINLM. For example, in Figure 13 In F3, the lower input limit voltage PINMIN, which serves as the input limit voltage PINLM, has a negative temperature characteristic as the first polarity. In this case, such as Figure 13 As shown in F1, the reference voltage VRC also exhibits the same negative temperature characteristic. Additionally, in Figure 16 In J3, the input upper limit voltage PINMAX, which is the input limit voltage PINLM, has a positive temperature characteristic as the first polarity. In this case, such as Figure 16 As shown in J1, the reference voltage VRC also has the same positive temperature characteristic.

[0155] Thus, in this embodiment, the temperature characteristic of the input limit voltage PINLM at the first input terminal of the operational amplifier OPD has the same first polarity as the temperature characteristic of the reference voltage VRC. Therefore, with respect to temperature changes, the input limit voltage PINLM and the reference voltage VRC change with the same temperature characteristic. Therefore, even when the power supply voltage VDD is reduced to a low voltage, the narrowing of the output voltage range of the operational amplifier OPD in the temperature compensation circuit 40 can be suppressed, and appropriate temperature compensation can be achieved.

[0156] Furthermore, in this embodiment, at the inflection point temperature of the temperature compensation voltage VCP, the temperature compensation voltage VCP becomes the reference voltage VRC. For example, in Figure 13 In F7, at a typical temperature, which serves as the inflection point temperature, the temperature compensation voltage VCP is equal to the reference voltage VRC. Figure 16 In J6, at a typical temperature, which serves as the inflection point temperature, the temperature compensation voltage VCP is also equal to the reference voltage VRC.

[0157] In this way, by using a temperature compensation voltage VCP, which becomes the reference voltage VRC at the inflection point temperature, to perform temperature compensation of the oscillation frequency, a temperature-compensated oscillation signal can be generated. Furthermore, since the reference voltage VRC has a temperature characteristic with a first polarity, the narrowing of the voltage range of the temperature compensation voltage VCP can be suppressed even when the power supply voltage VDD of the circuit device 20 is reduced.

[0158] Furthermore, in this embodiment, the temperature compensation circuit 40 outputs a temperature compensation voltage VCP within a voltage range defined by the difference between the output limit voltage of the operational amplifier OPD and the reference voltage VRC. The output limit voltage of the operational amplifier OPD is, for example, the maximum voltage of the operational amplifier OPD's output voltage VQ, VQMAX = VDL - VOVP. Alternatively, the output limit voltage of the operational amplifier OPD is, for example, the minimum voltage of the operational amplifier OPD's output voltage VQ, VQMIN = VOVN. Moreover, the voltage range of the temperature compensation voltage VCP can be expressed, for example, as shown in equation (5) above, as VRC ± (VQMAX - VRC), or as VRC ± (VQMIN - VRC). Therefore, the temperature compensation circuit 40 outputs the temperature compensation voltage VCP within a voltage range defined by the difference between the output limit voltages VQMAX and VQMIN and the reference voltage VRC, i.e., VQMAX - VRC or VQMIN - VRC.

[0159] In this way, by using a temperature compensation voltage VCP, which is defined by the voltage range of the difference between the output limit voltage of the operational amplifier OPD and the reference voltage VRC, the oscillation frequency of the oscillation signal can be temperature compensated, and a temperature-compensated oscillation signal can be generated.

[0160] Furthermore, in this embodiment, the slope of the first-order temperature characteristic of the reference voltage VRC is less than the slope of the first-order temperature characteristic of the input limit voltage. For example, in Figure 13 In the above, the slope of the first-order temperature characteristic of the reference voltage VRC shown in F1 is less than the slope of the first-order temperature characteristic of the input lower limit voltage PINMIN shown in F3. Furthermore, in Figure 16 In the above, the slope of the first-order temperature characteristic of the reference voltage VRC shown in J1 is less than the slope of the first-order temperature characteristic of the input upper limit voltage PINMAX shown in J3.

[0161] Thus, as Figure 13 F4 Figure 16 Similar to J4, proper temperature compensation can be achieved by setting the reference voltage VRC above the lower input limit voltage PINMIN or below the upper input limit voltage PINMAX at the lower temperature limit of the temperature range. In other words, it is possible to suppress the narrowing of the temperature compensation voltage VCP and achieve proper temperature compensation.

[0162] Furthermore, in this embodiment, the operational amplifier OPD includes a differential pair of transistors, the first polarity of which is determined by the temperature characteristics of the differential pair of transistors.

[0163] For example, Figure 9 The differential pair transistors in the operational amplifier (OPD) are bipolar transistors (TB3, TB4) or N-type MOS transistors. Furthermore, the lower input limit voltage PINMIN at the first input terminal of the OPD is determined by the temperature characteristics of the transistors in that differential pair. Figure 14 The differential pair transistors in the operational amplifier (OPD) are bipolar transistors (TG3, TG4) or P-type MOS transistors. Furthermore, the upper input limit voltage PINMAX at the first input terminal of the OPD is determined by the temperature characteristics of the transistors in this differential pair.

[0164] Thus, the first polarity of the input limit voltage PINLM, which serves as the first input terminal of the operational amplifier OPD, is determined based on the temperature characteristics of the transistors in the differential pair of the OPD. Furthermore, in this embodiment, the reference voltage VRC is made to have the same temperature characteristics as the first polarity of the input limit voltage PINLM determined as described above.

[0165] Furthermore, in this embodiment, the transistor in the differential pair is a bipolar transistor, and the first polarity is a characteristic determined by the temperature characteristics of the base-emitter voltage of the bipolar transistor. For example, Figure 9 The differential pair transistors in the operational amplifier OPD are bipolar transistors TB3 and TB4. The first polarity of the input lower limit voltage PINMIN is determined by VBE, which is the base-emitter voltage of bipolar transistors TB3 and TB4. Furthermore, Figure 14 The differential pair transistors in the operational amplifier OPD are bipolar transistors TG3 and TG4. The first polarity of the input upper limit voltage PINMAX is determined by VBE, which is the base-emitter voltage of bipolar transistors TG3 and TG4.

[0166] Thus, the first polarity of the input limit voltage PINLM, which serves as the first input terminal of the operational amplifier OPD, is determined based on the temperature characteristics of the base-emitter voltage of the bipolar transistor in the differential pair of the operational amplifier OPD.

[0167] Furthermore, in this embodiment, the transistors of the differential pair are npn bipolar transistors or N-type MOS transistors, the input limit voltage PINLM of the first input terminal of the operational amplifier OPD is the input lower limit voltage PINMIN, and the first polarity is negative. For example, Figure 9The differential pair transistors in the operational amplifier (OPD) are npn bipolar transistors TB3, TB4, or N-type MOS transistors. Furthermore, the lower input limit voltage PINMIN, which is the input limit voltage PINLM at the first input terminal of the OPD, is expressed as PINMIN = VBE + VOVN or PINMIN = VGS + VOVN. Moreover, VBE, the base-emitter voltage, and VGS, the gate-source voltage, have negative temperature characteristics, thus the first polarity is negative.

[0168] Thus, by taking into account the temperature characteristics of the base-emitter voltage of the npn bipolar transistor or the gate-source voltage of the N-type MOS transistor in the differential pair of the operational amplifier OPD, the polarity of the lower input limit voltage PINMIN of the first input terminal of the operational amplifier OPD is determined to be negative.

[0169] Furthermore, in this embodiment, within the temperature range for temperature compensation, the reference voltage VRC is above the lower input limit voltage PINMIN, and the reference voltage VRC at the inflection point temperature of the temperature compensation voltage VCP is below the lower input limit voltage PINMIN at the lower limit temperature of the temperature range. The temperature range for temperature compensation corresponds to the operating temperature range of the circuit device 20 and the oscillator 4 described above. For example, in Figure 13 In this context, the reference voltage VRC, represented by F1, becomes the voltage above the input lower limit voltage PINMIN, represented by F3. Furthermore, Figure 13 The reference voltage VRC at the inflection temperature of the temperature compensation voltage VCP shown in F7 is lower than the input lower limit voltage PINMIN at the lower limit temperature of the temperature range shown in F4.

[0170] Thus, within the temperature compensation range, the reference voltage VRC, which is above the lower input limit voltage PINMIN, is input to the first input terminal of the operational amplifier OPD, enabling the operational amplifier OPD to operate appropriately. Furthermore, since the reference voltage VRC at the inflection point temperature of the temperature compensation voltage VCP is lower than the lower input limit voltage PINMIN at the lower limit temperature of the temperature range, the voltage range of the temperature compensation voltage VCP, which varies based on the reference voltage VRC, can be expanded.

[0171] Furthermore, in this embodiment, the transistors of the differential pair are pnp bipolar transistors or P-type MOS transistors, the input limit voltage PINLM of the first input terminal of the operational amplifier OPD is the input upper limit voltage PINMAX, and the first polarity is positive. For example, Figure 14The differential pair transistors in the operational amplifier (OPD) are PNP bipolar transistors TG3, TG4, or P-type MOS transistors. Furthermore, the input limit voltage PINMAX, which is the input limit voltage PINLM at the first input terminal of the OPD, is expressed as PINMAX = VDL - VBE - VOVN or PINMAX = VDL - VGS - VOVN. Moreover, VBE, the base-emitter voltage, and VGS, the gate-source voltage, have negative temperature characteristics, thus the first polarity becomes positive.

[0172] Thus, by utilizing the temperature characteristics of the base-emitter voltage of the pnp bipolar transistor or the gate-source voltage of the P-type MOS transistor, which is the differential pair of the operational amplifier OPD, the polarity of the upper input voltage PINMAX at the first input terminal of the operational amplifier OPD is determined to be positive.

[0173] Furthermore, in this embodiment, within the temperature range of temperature compensation, the reference voltage VRC is below the upper input voltage PINMAX, and the reference voltage VRC at the inflection point temperature of the temperature compensation voltage VCP is higher than the upper input voltage PINMAX at the lower limit temperature of the temperature range. For example, in Figure 16 In this context, the reference voltage VRC shown by J1 becomes the voltage below the input upper limit voltage PINMAX shown by J3. Furthermore, Figure 16 The reference voltage VRC at the inflection temperature of the temperature compensation voltage VCP shown in J6 is higher than the upper input voltage PINMAX at the lower limit temperature of the temperature range shown in J4.

[0174] Thus, within the temperature compensation range, the reference voltage VRC, below the upper input voltage PINMAX, is input to the first input terminal of the operational amplifier OPD, enabling the operational amplifier OPD to operate appropriately. Furthermore, since the reference voltage VRC at the inflection point temperature of the temperature compensation voltage VCP is higher than the upper input voltage PINMAX at the lower limit temperature of the temperature range, the voltage range of the temperature compensation voltage VCP, which varies based on the reference voltage VRC, can be expanded.

[0175] In addition, such as Figure 3 As shown, the temperature compensation circuit 40 includes a current generation circuit 42 and a current-to-voltage conversion circuit 46. The current generation circuit 42 generates a temperature compensation current ICP based on the temperature detection voltage VTS. The current-to-voltage conversion circuit 46 has an operational amplifier OPD1, which converts the temperature compensation current ICP into a voltage, thereby generating a temperature compensation voltage VCP. Furthermore, a reference voltage VRC is input to the first input terminal of the operational amplifier OPD1.

[0176] In this way, the current-to-voltage conversion circuit 46 converts the temperature-compensated current ICP generated by the current generation circuit 42 based on the temperature detection voltage VTS into a voltage, thereby generating a temperature-compensated voltage VCP. Temperature compensation of the oscillation frequency of the oscillation signal is then performed based on this temperature-compensated voltage VCP. Furthermore, a reference voltage VRC with a first polarity temperature characteristic having the same polarity as the temperature characteristic of the input limit voltage PINLM is input to the first input terminal of the operational amplifier OPD1 of the current-to-voltage conversion circuit 46.

[0177] 4.1 calibration

[0178] In this embodiment, the reference voltage VRC is as follows: Figure 13 F1 Figure 16 As described in J1, it has a primary temperature characteristic; therefore, it may not be possible to generate a proper temperature compensation voltage VCP. However, as... Figure 3 As shown, the primary correction circuit 43 of the temperature compensation circuit 40 performs a primary correction for temperature compensation. Therefore, this primary correction can be used to compensate for the primary temperature characteristics of the reference voltage VRC. This point will be explained.

[0179] For example in Figure 3 In the case where the output voltage of the operational amplifier OPD2 is set to VC1 and the high-order current from the high-order correction circuit 44 is set to ICU, the temperature compensation voltage VCP can be expressed as shown in equation (11).

[0180]

Mathematical Expression 11

[0181] Furthermore, if the voltage VC1 and the reference voltage VRC are expressed in terms of a first degree relative to temperature (t), then it becomes the following equation (12).

[0182]

Mathematical Expression 12

[0183] Furthermore, when the above equation (12) is substituted into the above equation (11), the temperature compensation voltage VCP can be expressed as shown in the following equation (13).

[0184]

Mathematical Expression 13

[0185] Therefore, when c in equation (12) is not 0 and the reference voltage VRC has a first-order temperature characteristic such as ct+d, it can be seen from equation (13) that the temperature compensation voltage VCP can be adjusted by adjusting the first-order gain of the correction resistor RD3 in the first-order correction circuit 43.

[0186] That is, in this embodiment, such as Figure 3 As shown, the temperature compensation circuit 40 includes a primary correction circuit 43. Furthermore, the primary correction circuit 43 uses the inflection point of the temperature compensation voltage VCP as a reference to perform primary temperature characteristic compensation of the temperature compensation voltage based on the temperature characteristics of the reference voltage VRC.

[0187] Thus, as shown in equation (13) above, when the reference voltage VRC has a primary temperature characteristic, the primary correction circuit 43 of the temperature compensation circuit 40 can also be used to correct and cancel the primary temperature characteristic of the reference voltage VRC.

[0188] As explained above, the circuit arrangement of this embodiment includes: an oscillation circuit that oscillates an oscillator to generate an oscillation signal; a temperature compensation circuit having an operational amplifier that outputs a temperature compensation voltage of the oscillation frequency of the oscillation signal to the oscillation circuit based on a temperature detection voltage from a temperature detection circuit; and a reference voltage generation circuit for temperature compensation that generates a reference voltage for temperature compensation and outputs it to the temperature compensation circuit. Furthermore, the input limit voltage of the first input terminal of the operational amplifier has a temperature characteristic with a first polarity that is either positive or negative, and the reference voltage input to the first input terminal of the operational amplifier has a temperature characteristic with the same first polarity as the temperature characteristic of the input limit voltage.

[0189] According to this embodiment, the temperature characteristics of the input limit voltage and the reference voltage at the first input terminal of the operational amplifier in the temperature compensation circuit have the same first polarity. Therefore, the input limit voltage and the reference voltage change with the same polarity of temperature characteristics relative to temperature changes, enabling appropriate temperature compensation even when the power supply voltage is reduced.

[0190] Furthermore, in this embodiment, the temperature compensation voltage can also be a reference voltage at the inflection point temperature of the temperature compensation voltage.

[0191] In this way, temperature compensation of the oscillation frequency can be performed by using a temperature compensation voltage that becomes the reference voltage at the inflection point temperature, thereby generating an oscillation signal.

[0192] Furthermore, in this embodiment, the temperature compensation circuit can also output a temperature compensation voltage within the voltage range specified by the difference between the output limit voltage of the operational amplifier and the reference voltage.

[0193] In this way, the oscillation frequency of the oscillation signal can be temperature compensated by a temperature compensation voltage within a voltage range specified by the difference between the output limit voltage of the operational amplifier and the reference voltage, thereby generating an oscillation signal.

[0194] In addition, in this embodiment, the temperature compensation circuit may include a primary correction circuit, which uses the inflection point of the temperature compensation voltage as a reference to perform primary temperature characteristic compensation of the temperature compensation voltage based on the temperature characteristics of the reference voltage.

[0195] In this way, even when the reference voltage has a primary temperature characteristic, the primary correction circuit of the temperature compensation circuit can be used to correct and cancel out the primary temperature characteristic of the reference voltage.

[0196] In this embodiment, the slope of the first-order temperature characteristic of the reference voltage can be less than the slope of the first-order temperature characteristic of the input limit voltage.

[0197] In this way, appropriate temperature compensation can be achieved by setting the reference voltage above the lower limit of the input voltage or below the upper limit of the input voltage at the lower limit of the temperature compensation range.

[0198] In addition, in this embodiment, the operational amplifier may include a differential pair of transistors, the first polarity of which is determined by the temperature characteristics of the differential pair of transistors.

[0199] Thus, the first polarity of the input limit voltage, which serves as the first input terminal of the operational amplifier, is determined by the temperature characteristics of the transistors in the differential pair of the operational amplifier.

[0200] Alternatively, in this embodiment, the transistor of the differential pair may be a bipolar transistor, and the first polarity is determined by the temperature characteristics of the base-emitter voltage of the bipolar transistor.

[0201] Thus, the first polarity of the input limit voltage, which serves as the first input terminal of the operational amplifier, is determined based on the temperature characteristics of the base-emitter voltage of the bipolar transistor, which is the differential pair of the operational amplifier.

[0202] In addition, in this embodiment, the transistors of the differential pair may be npn bipolar transistors or N-type MOS transistors, the input limit voltage of the first input terminal of the operational amplifier may be the lower input limit voltage, and the first polarity may be negative.

[0203] In this way, by utilizing the temperature characteristics of the base-emitter voltage of the npn bipolar transistor or the gate-source voltage of the N-type MOS transistor, which is the differential pair of the operational amplifier, the polarity of the lower limit voltage of the first input terminal is determined to be negative.

[0204] In addition, in this embodiment, the reference voltage may be above the lower limit input voltage within the temperature range of temperature compensation, and the reference voltage at the inflection point temperature of the temperature compensation voltage may be lower than the lower limit input voltage at the lower limit temperature of the temperature range.

[0205] In this way, within the temperature compensation range, a reference voltage above the lower input limit voltage is input to the first input terminal of the operational amplifier, thereby enabling the operational amplifier to operate appropriately. Since the reference voltage at the inflection point temperature is lower than the lower input limit voltage, the voltage range of the temperature compensation voltage, which varies based on the reference voltage, can be expanded.

[0206] In addition, in this embodiment, the transistors of the differential pair may be pnp bipolar transistors or P-type MOS transistors, the input limit voltage of the first input terminal of the operational amplifier may be the upper limit voltage of the input, and the first polarity may be positive.

[0207] In this way, by utilizing the temperature characteristics of the base-emitter voltage of the pnp bipolar transistor or the gate-source voltage of the P-type MOS transistor, which is the differential pair of the operational amplifier, the polarity of the upper limit voltage of the first input terminal of the operational amplifier is determined to be positive.

[0208] In addition, in this embodiment, the reference voltage may be below the upper limit of the input voltage within the temperature range of temperature compensation, and the reference voltage at the inflection point temperature of the temperature compensation voltage may be higher than the upper limit of the input voltage at the lower limit temperature of the temperature range.

[0209] In this way, by inputting a reference voltage below the upper limit of the input voltage to the first input terminal of the operational amplifier, the operational amplifier can be made to work properly. The reference voltage at the inflection point temperature is higher than the upper limit of the input voltage, thus expanding the voltage range of the temperature compensation voltage that varies with reference voltage.

[0210] Alternatively, in this embodiment, the temperature compensation circuit may include: a current generation circuit that generates a temperature compensation current based on a temperature detection voltage; and a current-to-voltage conversion circuit having an operational amplifier that converts the temperature compensation current into a voltage to generate a temperature compensation voltage. Furthermore, a reference voltage can be input to the first input terminal of the operational amplifier.

[0211] In this way, a temperature compensation voltage is generated by converting the temperature compensation current generated based on the temperature detection voltage into a voltage, and the oscillation frequency of the oscillation signal is compensated for based on this temperature compensation voltage. Furthermore, a reference voltage with a temperature characteristic having the same polarity as the temperature characteristic of the input limit voltage is input to the first input terminal of the operational amplifier of the current-to-voltage conversion circuit.

[0212] Furthermore, the oscillator of this embodiment includes the circuit arrangement and oscillator described above.

[0213] Furthermore, while this embodiment has been described in detail above, those skilled in the art will readily understand that various modifications can be made without substantially departing from the new aspects and effects of this disclosure. Therefore, all such modifications are included within the scope of this disclosure. For example, a term described at least once in the specification or drawings along with a different, broader, or synonymous term can be replaced with that different term anywhere in the specification or drawings. Moreover, all combinations of this embodiment and its modifications are also included within the scope of this disclosure. Furthermore, the structure, operation, etc., of the circuit device, oscillator, etc., are not limited to those described in this embodiment, and various modifications can be implemented.

Claims

1. A circuit device, characterized in that, The circuit device includes: An oscillating circuit, which causes an oscillator to oscillate and generates an oscillating signal; A temperature compensation circuit has an operational amplifier that outputs a temperature compensation voltage at the oscillation frequency of the oscillation signal to the oscillation circuit based on the temperature detection voltage from the temperature detection circuit. as well as A reference voltage generation circuit for temperature compensation generates a reference voltage for temperature compensation and outputs it to the temperature compensation circuit. The input limiting voltage of the first input terminal of the operational amplifier has a temperature characteristic that is a first polarity, either positive or negative. The reference voltage input to the first input terminal of the operational amplifier has a temperature characteristic with the same polarity as the temperature characteristic of the input limit voltage.

2. The circuit device according to claim 1, characterized in that, At the inflection point temperature of the temperature compensation voltage, the temperature compensation voltage is the reference voltage.

3. The circuit device according to claim 1, characterized in that, The temperature compensation circuit outputs the temperature compensation voltage within a voltage range defined by the difference between the output limit voltage of the operational amplifier and the reference voltage.

4. The circuit device according to claim 1, characterized in that, The temperature compensation circuit includes a primary correction circuit, which uses the inflection point of the temperature compensation voltage as a reference to compensate for the primary temperature characteristics of the temperature compensation voltage based on the temperature characteristics of the reference voltage.

5. The circuit device according to claim 1, characterized in that, The slope of the first-order temperature characteristic of the reference voltage is less than the slope of the first-order temperature characteristic of the input limit voltage.

6. The circuit device according to claim 1, characterized in that, The operational amplifier includes a differential pair of transistors. The first polarity is determined by the temperature characteristics of the transistors in the differential pair.

7. The circuit device according to claim 6, characterized in that, The transistors in the differential pair are bipolar transistors. The first polarity is determined by the temperature characteristics of the base-emitter voltage of the bipolar transistor.

8. The circuit device according to claim 6, characterized in that, The transistors in the differential pair are npn bipolar transistors or N-type MOS transistors. The input limit voltage at the first input terminal of the operational amplifier is the input lower limit voltage. The first polarity is negative.

9. The circuit device according to claim 8, characterized in that, Within the temperature compensation range, the reference voltage is above the lower input limit voltage. The reference voltage at the inflection point temperature of the temperature compensation voltage is lower than the input lower limit voltage at the lower limit temperature of the temperature range.

10. The circuit device according to claim 6, characterized in that, The transistors in the differential pair are pnp bipolar transistors or P-type MOS transistors. The input limit voltage at the first input terminal of the operational amplifier is the upper input limit voltage. The first polarity is positive.

11. The circuit device according to claim 10, characterized in that, Within the temperature compensation range, the reference voltage is below the upper limit of the input voltage. The reference voltage at the inflection point temperature of the temperature compensation voltage is higher than the upper limit voltage of the input at the lower limit temperature of the temperature range.

12. The circuit device according to claim 1, characterized in that, The temperature compensation circuit includes: A current generation circuit that generates a temperature-compensated current based on the temperature detection voltage; and A current-to-voltage conversion circuit, having the operational amplifier, generates the temperature-compensated voltage by converting the temperature-compensated current into a voltage using the operational amplifier. The reference voltage is input to the first input terminal of the operational amplifier.

13. An oscillator, characterized in that, The oscillator comprises the circuit arrangement as described in any one of claims 1 to 12 and the oscillator.

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