Circuit arrangement and oscillator

Abstract

Provided are a circuit device and an oscillator that can achieve proper temperature compensation even when a power supply voltage is low. The circuit device (20) includes an oscillation circuit (30) that oscillates an oscillator (10) to generate an oscillation signal; a temperature compensation circuit (40) that outputs a temperature compensation voltage (VCP) of an oscillation frequency of the oscillation signal to the oscillation circuit (30) based on a temperature detection voltage (VTS) from a temperature detection circuit (50); a power supply circuit (90) that generates a power supply voltage of the temperature compensation circuit (40); and a reference voltage generation circuit (60) that generates a reference voltage (VRC) for temperature compensation and outputs the reference voltage (VRC) to the temperature compensation circuit (40). Furthermore, the reference voltage (VRC) has less noise than the power supply voltage (VDL), and the temperature characteristic of the power supply voltage (VDL) is flatter than the temperature characteristic of the reference voltage (VRC).

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. Furthermore, in conventional circuit devices, a circuit combining a bandgap reference circuit and a regulator is used as a voltage generation circuit capable of generating a voltage with low noise and flat temperature characteristics.

[0003] Existing technical documents

[0004] Patent documents

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

[0006] However, for example, when the externally supplied power supply voltage is reduced, it is found that there is a problem that it is difficult to achieve both low noise and flat temperature characteristics in the voltage generation circuit configured as described above.

[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 that outputs a temperature compensation voltage of the oscillation signal's oscillation frequency to the oscillation circuit based on a temperature detection voltage from a temperature detection circuit; a power supply circuit that generates a power supply voltage for the temperature compensation 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, wherein the noise of the reference voltage is less than that of the power supply voltage, and the temperature characteristic of the power supply voltage is flatter than that of the reference 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 the reference voltage generation circuit and the voltage supply of the power supply circuit.

[0013] Figure 5 This is a structural example of a voltage generation circuit for a reference voltage generation circuit.

[0014] Figure 6 This is a structural example of a reference circuit for a reference voltage generation circuit.

[0015] Figure 7 This is an example of the structure of an inverting amplifier circuit.

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

[0017] Figure 9 This is an example of the structure of a reference voltage generation circuit that generates a low-noise reference voltage.

[0018] Figure 10 This is an example of the structure of a power supply circuit that generates a power supply voltage with flat temperature characteristics.

[0019] Figure 11 This is an example of the structure of a reference voltage generation circuit and a power supply circuit.

[0020] Figure 12 This is a diagram illustrating an example of the noise characteristics of a regulated voltage.

[0021] Figure 13 This is a diagram illustrating an example of the temperature characteristics of a power supply voltage.

[0022] Figure 14 This is a structural example of a reference circuit for a power supply circuit.

[0023] Figure 15 This is a structural example of a reference circuit for a power supply circuit.

[0024] Figure 16 This is an example of the structure of a regulator.

[0025] Figure 17 This is a structural example of a current source for PTAT.

[0026] Figure 18 This is a structural example of a current source for CTAT.

[0027] Explanation of reference numerals in the attached figures

[0028] 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; 47…Third-order correction circuit; 48…Fourth-order correction circuit; 49…Fifth-order correction circuit; 50…Temperature detection circuit; 56, 58…Current source; 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; 92… Reference circuit; 96… Regulator; 97… Voltage divider circuit; 100… Control circuit; 110… Non-volatile memory; 200… Load circuit; ICP… Temperature compensation current; ICU… High-order current; OPD, OPD1, OPD2, OPE… Operational amplifiers; VCP… Temperature compensation voltage; VD… Reference power supply voltage; VDD, VDL… Power supply voltage; VRC, VRCN… Reference voltage; VRF, VRG… Voltage; VTS… Temperature detection voltage. Detailed Implementation

[0029] 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.

[0030] 1. Circuit device

[0031] 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, a reference voltage generation circuit 60, and a power supply circuit 90. 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.

[0032] 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.

[0033] 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.

[0034] 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 refers to a connection that can transmit electrical signals, and is a connection that can transmit information based on electrical signals. An electrical connection can also be a connection via passive components, etc.

[0035] 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.

[0036] 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 suppresses and 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.

[0037] The power supply circuit 90 is supplied with, for example, external power supply voltage and ground voltage, and supplies various power supply voltages to the internal circuits of the circuit device 20. For example, the power supply circuit 90 supplies power to various circuits of the circuit device 20, such as the power supply voltage regulated isotropic oscillation circuit 30, temperature compensation circuit 40, and temperature detection circuit 50. Furthermore, in Figure 1 In this circuit, the power supply circuit 90 generates a power supply voltage VDL for the temperature compensation circuit 40 and outputs it to the temperature compensation circuit 40. For example, the operational amplifier in the temperature compensation circuit 40 operates powered by this power supply voltage VDL. The operational amplifier is, for example, an amplifier used in the current-to-voltage conversion circuit or the temperature compensation correction circuit of the temperature compensation circuit 40.

[0038] 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.

[0039] Furthermore, in this embodiment, the noise of the reference voltage VRC generated by the reference voltage generation circuit 60 is less than the noise of the power supply voltage VDL generated by the power supply circuit 90. That is, the reference voltage generation circuit 60 generates a reference voltage VRC with lower noise than the power supply voltage VDL from the power supply circuit 90, and outputs it to the temperature compensation circuit 40. Here, the noise is, for example, voltage noise, or noise power represented by the value of RMS (Root Mean Square).

[0040] On the other hand, the temperature characteristic of the power supply voltage VDL generated by the power supply circuit 90 is flatter than that of the reference voltage VRC. For example, the voltage fluctuation of the power supply voltage VDL within the operating temperature range specified by the circuit device 20 and the oscillator is less than the voltage fluctuation of the reference voltage VRC within the same operating temperature range, resulting in a flat temperature characteristic. In other words, the slope of the primary temperature characteristic of the power supply voltage VDL is less than the slope of the primary temperature characteristic of the reference voltage VRC. Here, as an example, the operating temperature range is -40℃ to 105℃, but it is not limited to this; for example, it could be -40℃ to 125℃ or 0℃ to 85℃, etc.

[0041] Thus, in this embodiment, a voltage with uneven temperature characteristics compared to the power supply voltage VDL but lower noise than the power supply voltage VDL is used as the reference voltage VRC for temperature compensation in the temperature compensation circuit 40. On the other hand, a voltage with high noise compared to the reference voltage VRC but flatter temperature characteristics than the reference voltage VRC is used as the power supply voltage VDL of the temperature compensation circuit 40. In this way, for example, even if the power supply voltage supplied from the outside is low, temperature compensation can be achieved without compromising characteristics.

[0042] Figure 2 A detailed structural example of the circuit device 20 and oscillator 4 in this embodiment is shown. Figure 2In the circuit device 20, in addition to the oscillation circuit 30, temperature compensation circuit 40, reference voltage generation circuit 60, and power supply circuit 90, it also includes a temperature detection circuit 50, an output circuit 80, 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.

[0043] 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.

[0044] 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.

[0045] The temperature compensation circuit 40 performs analog temperature compensation, for example, based on polynomial approximation. For instance, when the temperature compensation voltage VCP is approximated using a polynomial to compensate for the frequency-temperature characteristics of the oscillator 10, 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 addition processing of analog signals such as current and voltage signals. For example, when the temperature compensation voltage VCP is approximated using a high-order polynomial, the 0th-order coefficient, 1st-order coefficient, and high-order coefficients of the polynomial are stored as 0th-order correction data, 1st-order correction data, and high-order correction data, respectively, in a storage unit implemented, for example, a non-volatile memory 110. High-order coefficients are, for example, coefficients of orders greater than 1st, and high-order correction data are correction data corresponding to the high-order coefficients. For example, when the temperature compensation voltage VCP is approximated using a 3rd-order polynomial, the 0th-order coefficient, 1st-order coefficient, 2nd-order coefficient, 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. Furthermore, the temperature compensation circuit 40 performs temperature compensation based on correction data from the 0th to the 3rd order. In this case, the 2nd order correction data can also be omitted, and temperature compensation based on the 2nd order correction data can be performed. Additionally, 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, respectively. The temperature compensation circuit 40 performs temperature compensation based on the 0th to the 5th order correction data. In this case, the 2nd or 4th order correction data can also be omitted, and temperature compensation based on the 2nd or 4th order correction data can be performed. Furthermore, the degree of the polynomial approximation is arbitrary; for example, a polynomial approximation with a degree greater than 5 can be performed.

[0046] 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 with automatic configuration routing based on gate arrays or the like.

[0047] 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.

[0048] 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. Furthermore, this clock signal CK is output externally 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 and outputs the clock signal CK generated by this clock signal generation circuit.

[0049] 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 BGR voltage. BGR is an abbreviation for bandgap reference. The reference voltage generation circuit 60 generates the reference voltage VRC based on the BGR voltage 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 BGR voltage. For example, the regulator adjusts the power supply voltage VDD based on the BGR voltage, 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 BGR voltage generated by the reference circuit or the voltage generated by the regulator based on the BGR voltage 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, as described later, multiple reference voltages can be generated by making the resistor division ratios in the voltage generation circuit different and supplied to the temperature compensation circuit 40.

[0050] 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, supplying 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 voltage isotropic oscillation circuit 30 obtained by adjusting the power supply voltage VDD.

[0051] Furthermore, in this embodiment, the power supply circuit 90 generates a power supply voltage VDL with a flat temperature characteristic and supplies it to the temperature compensation circuit 40. For example, the power supply circuit 90 has a reference circuit that generates a power supply reference voltage, and the power supply voltage VDL is generated based on the power supply reference voltage. Alternatively, the power supply circuit 90 may also have a regulator that generates the power supply voltage VDL based on the power supply reference voltage. For example, the regulator adjusts the power supply voltage VDD based on the power supply reference voltage to generate the power supply voltage VDL. The operational amplifier or the like in the temperature compensation circuit 40 then operates using this power supply voltage VDD as a power source.

[0052] The oscillation circuit 30 includes a variable capacitor circuit 32 whose capacitance change characteristic with respect 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 a 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. This achieves temperature compensation to offset the increase in oscillation frequency. Conversely, 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. This achieves temperature compensation to offset the decrease in oscillation frequency. Alternatively, the oscillation circuit 30 can be equipped with a variable capacitor circuit whose capacitance is controlled by an externally input frequency control voltage, allowing the oscillation frequency to be variably controlled by this frequency control voltage.

[0053] 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.

[0054] 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 a function current. Furthermore, 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.

[0055] 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 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 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.

[0056] Figure 4 An example of the structure of the high-order correction circuit 44 is shown. Figure 4 In this circuit, the higher-order correction circuit 44 includes a 3rd-order correction circuit 47, a 4th-order correction circuit 48, and a 5th-order correction circuit 49. Alternatively, the higher-order correction circuit 44 may also include 2nd-order or higher-order correction circuits. The 3rd-order correction circuit 47 outputs a 3rd-order current that is approximately a 3rd-order function. Similarly, the 4th-order correction circuit 48 and the 5th-order correction circuit 49 output 4th-order currents that are approximately 4th-order functions and 5th-order currents that are approximately 5th-order functions, respectively. Furthermore, the temperature detection voltage VTS from the temperature detection circuit 50 and the reference voltage VRC from the reference voltage generation circuit 60 are input to the 1st-order correction circuit 43. Additionally, the temperature detection voltage VTS from the temperature detection circuit 50 and the reference voltages VRC3, VRC4, and VRC5 from the reference voltage generation circuit 60 are input to the 3rd-order correction circuit 47, the 4th-order correction circuit 48, and the 5th-order correction circuit 49. Finally, the reference voltage generation circuit 60 outputs a reference voltage VRC0 to the temperature detection circuit 50.

[0057] For example, each of the correction circuits 47 (3rd correction), 48 (4th correction), and 49 (5th correction) includes a differential circuit. The differential circuit includes: a first transistor and a second transistor, which are connected in parallel between the high-potential side power supply node and the first node, forming a differential pair; and a current source transistor, which is disposed between the first node and the low-potential side power supply node, through which a bias current, serving as a reference current, flows. Furthermore, a temperature detection voltage VTS is input to the gate of the first transistor of the differential pair, and a reference voltage VRC3, VRC4, or VRC5 is input to the gate of the second transistor of the differential pair.

[0058] like Figure 3As 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.

[0059] 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 of the operational amplifier OPD1. The resistor RD is positioned between the output terminal and the inverting input terminal of the operational amplifier OPD1. Furthermore, in Figure 3 In the circuit, 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 as follows: Figure 4 As shown, it is configured without a capacitor CD.

[0060] so, Figure 3 The temperature compensation circuit 40 includes a primary correction circuit 43 and a higher-order correction circuit 44 for receiving the input temperature detection voltage VTS. It also includes a current generation circuit 42 that generates a temperature compensation current ICP through the primary correction circuit 43 and the higher-order correction circuit 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 via the current-to-voltage conversion circuit 46.

[0061] Figure 5 An example of the structure of a voltage generation circuit 68 provided in a reference voltage generation circuit 60 is shown. This voltage generation circuit 68 divides the reference power supply voltage VD through a resistor circuit, thereby generating reference voltages VRC…VRCN. For example, in… Figure 5In this process, the reference power supply voltage VD is divided by a resistor circuit consisting of resistors R11 and R12 to generate the reference voltage VRC. Similarly, the reference power supply voltage VD is divided by a resistor circuit consisting of resistors RN1 and RN2 to generate the reference voltage VRCN. Here, the reference power supply voltage VD is either the voltage VRF generated by a reference circuit such as the BGR circuit, as described later, or the voltage generated by the regulator based on the voltage VRF.

[0062] 2. Reference voltage generation circuit and power supply circuit

[0063] Figure 6 An example of the structure of a reference circuit 62 disposed in a reference voltage generation circuit 60 is shown. This reference circuit 62 is a BGR circuit (bandgap reference circuit), more specifically a Widlar-type BGR circuit. The 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, the reference circuit 62 is not limited to... Figure 6 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] 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.

[0065] 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.

[0066] 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.

[0067] 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.

[0068] Here, will Figure 6 Let 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)}.

[0069] Furthermore, the voltage across resistor R1 becomes VBE1 - VBE2 = ΔVBE, therefore I1 = ΔVBE / R1. Thus, the voltage VRF = VBE1 + I1·R3 is given by equation (1). Additionally, in this embodiment, the same reference numerals are used to represent the resistors and their resistance values. For example, the resistance values ​​of resistors R1, R2, and R3 are also denoted as R1, R2, and R3.

[0070]

Mathematical Formula 1

[0071]

[0072] The first term VBE1 in equation (1) 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 using the positive temperature characteristic of the second term to cancel the negative temperature characteristic of the first term in equation (1) 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 (1) 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.

[0073] Here, with the threshold voltage of the transistor set to Vth, the gate-source voltage set to VGS, and the drain-source voltage set to VDS, the overdrive voltage can be expressed as VOV = VGS - Vth, which indicates the extent to which VGS exceeds Vth. For the transistor to operate in the saturation region, VDS > VOV is required.

[0074] Furthermore, as mentioned above, the voltage of VRF when the temperature characteristic becomes flat is approximately 1.25V. Additionally, when the overdrive voltage of the N-type transistor TA4 is set to VOVN, the overdrive voltage VOVN that allows transistor TA4 to operate in the saturation region is approximately 0.1V to 0.2V. Therefore, in order to... Figure 6 The reference circuit 62 outputs a voltage VRF with a flat temperature characteristic, requiring the supplied power supply voltage to be approximately VDD > VRF + VOVN = 1.35V~1.45V. Therefore, if the lower limit of VDD becomes, for example, 1.1V due to a lower supply voltage, there is a possibility of… Figure 6 The reference circuit 62 cannot generate a voltage VRF with low noise and flat temperature characteristics, which is a problem.

[0075] In addition, Figure 6 The reason for including bipolar transistor TA3 is twofold: firstly, it determines the operating point of bipolar transistor TA2, and secondly, it adjusts the load current flowing to the load circuit supplied with voltage VRF. Specifically, by including bipolar transistor TA3, the collector-emitter voltage of bipolar transistor TA2 is prevented from decreasing, allowing it to operate in the active region. This achieves the first function. Furthermore, when the load current IL flows through VRF, the gate voltage of transistor TA4 is adjusted via bipolar transistor TA3, applying feedback to keep voltage VRF constant. This achieves the second function. 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.

[0076] For example, if the current flowing to transistor TA4 is set to ITA4, then ITA4 = I1 + I2 + IL. Furthermore, in Figure 6 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.

[0077] 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.

[0078] 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 6 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.

[0079] Figure 7 An example of an amplifier circuit structure 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 corresponds, for example, 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 of operational amplifier OPD, 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.

[0080] Figure 7 The output voltage VQ of the amplifier circuit is shown in equation (2).

[0081]

Mathematical Formula 2

[0082]

[0083] From equation (2) above, it can be seen that the noise of the reference voltage VRC is (1+RF / RS) times. Therefore, in order to make it comparable to... Figure 3 The output voltage VQ corresponding to the temperature compensation voltage VCP becomes low noise, and the reference voltage VRC needs to be a low noise voltage.

[0084] Figure 8This is an example of the circuit structure of an operational amplifier (OPD). Figure 8 The differential section of the operational amplifier (OPD) includes: transistors TB1 and TB2 forming a current mirror circuit; bipolar transistors TB3 and TB4 as a differential pair; and transistor TB5 as a current source. Transistor TB1 is located between nodes VDL and NB1, and transistor TB2 is located between nodes VDL and NB2. The gates of transistors TB1 and TB2 are connected to node NB1. Bipolar transistor TB3 is located between nodes NB1 and NB3, and its base is input with a voltage NIN from the inverting input terminal. Bipolar transistor TB4 is located between nodes NB2 and NB3, and its base is input with a voltage PIN from the non-inverting input terminal. Alternatively, a variation using a MOS transistor instead of bipolar transistors TB3 and TB4 can be implemented. Transistor TB5 is located between nodes NB3 and VSS, and its gate is input with a bias voltage VBS.

[0085] 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 transistor TB6 is connected to node NB2, which serves as the output node for the differential section, and the gate of transistor TB7 is biased by input voltage VBS. The output voltage VQ is output from node NB4, between transistors TB6 and TB7. Capacitor CB is used for phase compensation.

[0086] Here, let Figure 8 Let the overdrive voltage of the P-type transistor TB6 be VOVP, and the overdrive voltage of the N-type transistor TB7 be VOVN. Therefore, regarding... Figure 7 The voltage range of the output voltage VQ of the amplifier circuit (operational amplifier OPD) is subject to the following relationship (3).

[0087]

Mathematical Expression 3

[0088]

[0089] That is, the lower limit of the output voltage VQ is called VOVN, and the upper limit of the output voltage VQ is called VDL-VOVP. Therefore, when the power supply voltage VDL has a temperature characteristic, the voltage range of the output voltage VQ will shrink. Therefore, it is desirable for the power supply voltage VDL to have a flat temperature characteristic.

[0090] In this case, consider using the method provided by Figure 6 The method described herein uses the voltage VRF generated by the reference circuit 62 to generate the power supply voltage VDL. For example, the regulator uses the voltage VRF as a reference voltage to generate the power supply voltage VDL.

[0091] However, when the external power supply voltage VDD is reduced to a low voltage, as described above, Figure 6 The voltage VRF generated by the reference circuit 62 will not have a flat temperature characteristic. Therefore, when the supply voltage VDL is generated based on such a voltage VRF, the supply voltage VDL will not have a flat temperature characteristic. Figure 7 The voltage range of the output voltage VQ of the amplifier circuit is reduced. Therefore, when... Figure 7 The amplifier circuit is used as Figure 3 In the case of the current-to-voltage conversion circuit 46, the voltage range of the temperature compensation voltage VCP is reduced, resulting in a situation where temperature compensation cannot be performed.

[0092] Regarding the issue of the reduced voltage range of the temperature compensation voltage VCP as described above, it is also considered to increase... Figure 2 The variable capacitor circuit 32 uses a varactor diode and other variable capacitor elements to increase sensitivity as a solution. However, when the capacitance of the variable capacitor elements is increased to improve sensitivity as described above, the capacitance deviation and variation become larger, leading to problems such as increased complexity in temperature compensation.

[0093] In addition, as Figure 6 The reference circuit 62 generates a low-noise bandgap reference voltage for the voltage VRF. Therefore, it is preferable that the power supply voltage VDL supplied by the power supply circuit 90 is generated based on the low-noise bandgap reference voltage. However, when the power supply voltage VDD is lowered, the operating conditions of the reference circuit 62 become more demanding. When VDD is below, for example, 1.5V to 1.6V, the temperature characteristics of the voltage VRF cannot be flattened. Therefore, as the power supply voltage VDD is lowered, low noise becomes a trade-off with flattening the temperature characteristics.

[0094] On the other hand, Figure 3 In the temperature compensation circuit 40, when the reference voltage VRC input to the operational amplifiers OPD1 and OPD2, and the reference voltage input to the higher-order correction circuit 44 ( Figure 4 When the noise of VRC3, VRC4, and VRC5 increases, as explained in equation (2) above, the increased noise is amplified. Consequently, the noise of the temperature compensation voltage VCP increases, and the frequency noise of the clock signal output by oscillator 4 increases.

[0095] In addition, the temperature compensation circuit 40 uses operational amplifiers OPD1 and OPD2 to generate a temperature compensation voltage VCP. Therefore, the power supply voltages VDL of the operational amplifiers OPD1 and OPD2 need to maintain a high voltage over a wide temperature range. However, when the power supply voltage VDL has a positive or negative temperature characteristic, the power supply voltage VDL may decrease within a specific temperature range. For example, when the power supply voltage VDL has a negative temperature characteristic, the power supply voltage VDL decreases within the temperature range on the high-temperature side, and when the power supply voltage VDL has a positive temperature characteristic, the power supply voltage VDL decreases within the temperature range on the low-temperature side. As shown in the above equation (3), since VQ < VDL - VOVP, when the power supply voltage VDL decreases, the upper limit of the output voltage VQ = VCP decreases, and the operational amplifiers OPD1 and OPD2 cannot operate stably.

[0096] Therefore, in the present embodiment, regarding the reference voltage of the temperature compensation circuit 40, the reference voltage generation circuit 60 generates a low-noise reference voltage VRC and supplies it to the temperature compensation circuit 40. For example, the reference voltage generation circuit 60 uses a reference circuit 62 such as a BGR circuit to generate a low-noise reference voltage VRC and supplies it to the temperature compensation circuit 40. On the other hand, regarding the power supply voltage of the temperature compensation circuit 40, the power supply circuit 90 generates a power supply voltage VDL with a flat temperature characteristic and supplies it to the temperature compensation circuit 40. For example, the power supply circuit 90 uses a reference circuit different from the BGR circuit to generate a power supply voltage VDL with a flat temperature characteristic and supplies it to the temperature compensation circuit 40.

[0097] In this way, the temperature compensation circuit 40 can generate a low-noise temperature compensation voltage VCP using the low-noise reference voltage VRC. Therefore, it is possible to reduce the noise of the clock signal generated by the oscillation of the oscillation circuit 30. In addition, the operational amplifiers and the like of the temperature compensation circuit 40 can be supplied with a power supply voltage VDL having a flat temperature characteristic and operate. Therefore, for example, when the power supply voltage VDD is lowered, it is possible to prevent the output voltage range of the operational amplifier from being reduced and proper temperature compensation from being impossible.

[0098] Next, use Figure 9 to describe the basic structure of the reference voltage generation circuit 60. In Figure 9 C1, the reference voltage generation circuit 60 includes a reference circuit 62 and a regulator 66. The reference circuit 62 generates a low-noise voltage VRF, and the regulator 66 generates a voltage VRG based on the voltage VRF. For example, the regulator 66 adjusts the power supply voltage VDD based on the voltage VRF, thereby generating the voltage VRG. And the reference voltage generated based on this voltage VRG is supplied to the temperature compensation circuit 40. Specifically, the voltage VRG from the regulator 66 is used as Figure 5The reference power supply voltage VD is supplied to the voltage generation circuit 68, thereby generating VRC~VRCN as the reference voltage. Figure 9 In C2, the reference voltage generation circuit 60 includes a reference circuit 62, which generates a low-noise voltage VRF. A reference voltage generated based on this voltage VRF is supplied to the temperature compensation circuit 40. Specifically, the voltage VRF from the reference circuit 62 serves as the reference power supply voltage VD to... Figure 5 The voltage generation circuit 68 supplies and generates VRC~VRCN as a reference voltage.

[0099] For example, in Figure 9 In the structure of C2, when the output impedance of the reference circuit 62 is high, there is a problem that the voltage VRF changes due to the load current generated in the load circuit 200. Regarding this point, Figure 9 In the structure of C1, a regulator 66 with high input impedance and low output impedance is provided. Therefore, it has the advantage of supplying a stable voltage VRG and current even when load current is generated. On the other hand, when the output impedance of the reference circuit 62 is low, by employing... Figure 9 The structure shown in C2 can omit the regulator 66, thus enabling the circuit to be miniaturized.

[0100] As Figure 9 The reference circuit 62 shown in C1 can be used Figure 6 The circuit includes a Widlar-type BGR circuit and a current-depletion source-type circuit. The current-depletion source-type circuit is a reference circuit utilizing a depletion-type transistor. Furthermore, as regulator 66, regulators with Nch input stage and Nch output stage, and regulators with Nch input stage and Pch output stage, as described later, can be used. Additionally, as reference circuit 62 shown in C2, it is possible to use... Figure 6 Widlar-type BGR circuits, etc.

[0101] Figure 10 This illustrates the basic structure of power supply circuit 90. Figure 10 In this circuit, the power supply circuit 90 includes a reference circuit 92 and a regulator 96. The reference circuit 92 generates a voltage VRF with a flat temperature characteristic, and the regulator 96 generates a voltage VRG based on the voltage VRF, which is supplied to the temperature compensation circuit 40 as the power supply voltage VDL. For example, the regulator 96 regulates the power supply voltage VDD based on the voltage VRF, thereby generating the power supply voltage VDL and supplying it to the temperature compensation circuit 40.

[0102] As Figure 10The reference circuit 92 can utilize circuits based on a PTAT current source and an Nch diode connection, as described later, as well as circuits based on a PTAT current source and a CTAT current source. PTAT stands for Proportional To Absolute Temperature, and CTAT stands for Complementary To Absolute Temperature. PTAT current is the current that increases with rising temperature, while CTAT current is the current that decreases with rising temperature. Furthermore, the regulator 96 can utilize regulators with both an Nch input stage and an Nch output stage, as well as regulators with both an Nch input stage and a Pch output stage.

[0103] Figure 11 An example of the structure of the reference voltage generation circuit 60 and the power supply circuit 90 is shown. The current source 56 is used to direct the current of PTAT, which increases with temperature, to the reference circuit 62 and regulator 66 of the reference voltage generation circuit 60 and the reference circuit 92 of the power supply circuit 90.

[0104] The reference voltage generation circuit 60 includes a reference circuit 62, a regulator 66, and a voltage generation circuit 68. The reference circuit 62 is as follows: Figure 6 As described, a low-noise voltage VRF is generated as the BGR voltage. Regulator 66 generates a voltage VRG as a low-noise voltage by regulating, for example, the supply voltage VDD, based on the voltage VRF. Figure 5 The reference power supply voltage VD. Furthermore, the voltage generation circuit 68 generates reference voltages VRC~VRCN based on the reference power supply voltage VD. Additionally, as... Figure 9 As shown in C2, the voltage generation circuit 68 can also use the voltage VRF from the reference circuit 62 as the reference power supply voltage VD to generate reference voltages VRC~VRCN. Then, as... Figure 4 As shown, the temperature compensation circuit 40 generates a temperature compensation voltage VCP based on the reference voltages VRC to VRCN. Furthermore, in this embodiment, the reference voltages VRC to VRCN are appropriately and representatively referred to as the reference voltage VRC.

[0105] The power supply circuit 90 includes a reference circuit 92 and a regulator 96. The reference circuit 92 generates a voltage VRF with a flat temperature characteristic. A specific example of the structure of the reference circuit 92 will be described later. The regulator 96 generates a voltage VRG by adjusting, for example, the power supply voltage VDD based on the voltage VRF. Furthermore, the regulator 96 supplies the voltage VRG as the power supply voltage VDL to the temperature compensation circuit 40.

[0106] Figure 12 This is a diagram illustrating an example of the noise characteristics of a voltage VRG used as a voltage regulator. Figure 12A1 is the noise characteristic of the voltage VRG generated by the regulator 66 of the reference voltage generation circuit 60. In the reference voltage generation circuit 60, such as... Figure 6 As shown, reference circuit 62 generates a low-noise BGR voltage as voltage VRF. Therefore, as shown in A1, the voltage VRG generated based on voltage VRF as BGR voltage becomes low-noise, and the reference voltage VRC generated based on voltage VRG also becomes a low-noise voltage.

[0107] Figure 12 A2 and A3 are the noise characteristics of the voltage VRG generated by the regulator 96 of the power supply circuit 90. The regulator 96 is based on the noise characteristics of the voltage VRG generated by the regulator 96, as described later. Figure 14 , Figure 15 The reference circuit 92 described herein generates a voltage VRF, which in turn generates a voltage VRG, and supplies the voltage VRG as the power supply voltage VDL to the temperature compensation circuit 40. Figure 12 A2 is based on Figure 14 The noise characteristics of the voltage VRF and voltage VRG of the reference circuit 92, A3 is based on Figure 15 The noise characteristics of the voltage VRG of the reference circuit 92 are examined. Furthermore, the voltage VRF generated by the reference circuit 92 of the power supply circuit 90 has increased noise compared to the voltage VRF generated by the reference circuit 62 of the reference voltage generation circuit 60. Therefore, as... Figure 12 As shown in A2 and A3, the voltage VRG generated by regulator 96 based on voltage VRF has increased noise compared to A1.

[0108] Figure 13 This is a diagram showing an example of the temperature characteristics of the voltage VRG as a regulating voltage. Figure 13 B1 is the temperature characteristic of the voltage VRG generated by the regulator 66 of the reference voltage generation circuit 60. The reference circuit 62 generates the BGR voltage as the voltage VRF, but as in... Figure 6 As explained, when the power supply voltage VDD is low, a voltage VRF with a flat temperature characteristic cannot be generated. That is, if the power supply voltage VDD is high, the negative temperature characteristic of the first term in equation (1) above is offset by the positive temperature characteristic of the second term, and a voltage VRF with a flat temperature characteristic and constant voltage within the operating temperature range can be generated. For example, the voltage VRF with a flat temperature characteristic is about 1.25V. However, when the power supply voltage VDD becomes low, the voltage VRF generated by the reference circuit 62 becomes, for example, a negative temperature characteristic. Therefore, as Figure 13 As shown in B1, the voltage VRG generated by regulator 66 based on voltage VRF also has a negative temperature characteristic.

[0109] Figure 13B2 and B3 are the temperature characteristics of the voltage VRG generated by the regulator 96 of the power supply circuit 90. Figure 13 B2 is based on Figure 14 The temperature characteristics of the voltage VRF and voltage VRG of the reference circuit 92, B3 is based on Figure 15 The reference circuit 92 has a voltage VRF and a voltage VRG with temperature characteristics. The regulator 96 is based on the voltage VRG described later. Figure 14 , Figure 15 The reference circuit 92 generates a voltage VRF, which in turn generates a voltage VRG, and supplies the voltage VRG as the power supply voltage VDL to the temperature compensation circuit 40. Furthermore, the voltage VRF generated by the reference circuit 92 of the power supply circuit 90 has a flatter temperature characteristic compared to the voltage VRF generated by the reference circuit 62 of the reference voltage generation circuit 60. Therefore, as... Figure 13 As shown in B2 and B3, the voltage VRG generated by regulator 96 based on voltage VRF has a flatter temperature characteristic compared to B1. For example, the temperature characteristics of B2 and B3 become less than 0.3mV / ℃, and the voltage variation in the temperature range of -40℃ to 130℃ also becomes less than 50mV.

[0110] Thus, in this embodiment, as Figure 12 As shown in A1, the reference voltage generation circuit 60 generates a reference voltage VRC using a voltage VRG with lower noise than A2 and A3. On the other hand, as... Figure 13 As shown in B2 and B3, the power supply circuit 90 generates a power supply voltage VDL through a voltage VRG with a flatter temperature characteristic than B1. Therefore, even when a trade-off is made between low noise and a flat temperature characteristic by lowering the power supply voltage VDD, a low-noise voltage can be supplied to the temperature compensation circuit 40 for the reference voltage VRC, and a voltage with a flat temperature characteristic can be supplied to the temperature compensation circuit 40 for the power supply voltage VDL.

[0111] For example, when based on the Figure 6 When the voltage generated by the reference circuit 62 generates the power supply voltage VDL of the temperature compensation circuit 40, such as Figure 13 As shown in B1, a voltage that becomes less than 0.85V at 100°C is used to generate the power supply voltage VDL. Therefore, it is difficult to make the operational amplifier of the temperature compensation circuit 40 operate properly, the voltage range of the temperature compensation voltage VCP is narrowed, and proper temperature compensation cannot be achieved. In contrast, with the flat temperature characteristics of B2 and B3, a voltage VRG that becomes greater than 0.95V at 100°C can be used as the power supply voltage VDL. Therefore, the operational amplifier of the temperature compensation circuit 40 can operate properly, and the situation where the voltage range of the temperature compensation voltage VCP is narrowed, preventing the inability to achieve temperature compensation, can be avoided.

[0112] Figure 14 This is a structural example of the reference circuit 92 for the power supply circuit 90. Figure 14 It is the reference circuit 92 for PTAT mode, corresponding to Figure 10 The document describes a structure example of a PTAT current source connected to an Nch diode. Figure 14 The reference circuit 92 includes a transistor TC1, a resistor RC1, and a 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 fed by a bias voltage VBPT for PTAT. This bias voltage VBPT is, for example, supplied by... Figure 11 The current source 56 of PTAT controls the current IPT of PTAT, thereby directing the current IPT of PTAT to resistor RC1. Resistor RC1 is a variable resistor connected in series with transistor TC1 between node VDD and node NC1. The voltage VRF output from 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, N-type transistor TC2 is connected by a diode.

[0113] exist Figure 14 In the reference circuit 92, when the gate-source voltage of transistor TC2 is set to VGS and the resistance value of resistor RC1 is represented by the same reference numeral RC1, a voltage of VRF = VGS + RC1·IPT is output from the output node NCQ.

[0114] 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. Furthermore, the current IPT of PTAT has a positive temperature characteristic, so by adjusting the resistance value of RC1, a voltage VRF with a flat temperature characteristic can be generated. For example, when VGS = Vth = approximately 0.4V, RC1·IPT becomes approximately 0.2V when adjusted to a flat temperature characteristic. Therefore, the voltage VRF generated by reference circuit 92 becomes approximately 0.6V, which is... Figure 6 Compared to the reference circuit 62, it can generate a voltage VRF with a flat temperature characteristic. However, adjustments for process variations are required.

[0115] Figure 15 This is also a structural example of the reference circuit 92 for the power supply circuit 90. Figure 15 It is the reference circuit 92 of the PTAT+CTAT method, corresponding to Figure 10 The structure example of the PTAT current source + CTAT current source described herein. Figure 15The reference circuit 92 includes transistors TH1 and TH2 and resistors RH1, RH2, and RH3. Transistor TH1 and resistor RH1 are connected in series between the nodes of VDD and NH1. Furthermore, transistor TH2 and resistor RH2 are connected in parallel with transistor TH1 and resistor RH1, connected in series between the nodes of VDD and NH1. Also, resistor RH3 is located between the nodes of NH1 and VSS.

[0116] Transistors TH1 and TH2 are P-type MOS transistors. Furthermore, a bias voltage VBPT for PTAT is input to the gate of transistor TH1. Consequently, the current IPT, which increases with temperature, flows to resistor RH1. Here, in... Figure 15 In this circuit, the resistance value of resistor RH1 is variable. Additionally, a bias voltage VBCT for CTAT is input to the gate of transistor TH2. Consequently, the current ICT, which decreases with increasing temperature, flows to resistor RH2. Furthermore, a current ITOT = IPT + ICT flows through resistor RH3.

[0117] exist Figure 15 In the reference circuit 92, the voltage VRF, VRF = RH1·IPT + RH3·(IPT + ICT) = RH1·IPT + RH3·ITOT, is output from the output node NHQ between transistor TH1 and resistor RH1. Furthermore, the current IPT has a positive temperature characteristic, and the current ICT has a negative temperature characteristic; therefore, by adjusting the resistance value of resistor RH1, a voltage VRF with a flat temperature characteristic can be generated. Additionally, although by... Figure 15 The resistor RH3 was replaced with an N-type MOS transistor to achieve low noise, but the current balance adjustment became slightly more difficult.

[0118] exist Figure 14 In the reference circuit 92, a low voltage VRF, such as 0.6V, is generated. In contrast, in Figure 15 The reference circuit 92 has a voltage ratio that can generate Figure 14 Advantages of high VRF. For example, as described later. Figure 16 As shown, voltage VRF is input to operational amplifier OPE of regulator 96, but operational amplifier OPE has an input lower limit voltage. Furthermore, when voltage VRF is too low, it is possible for it to fall below this input lower limit voltage, but according to... Figure 15 The reference circuit 92 can prevent such a situation from occurring.

[0119] Figure 16 Show Figure 11 Examples of the structures of regulators 66 and 96. Regulator 66 includes an operational amplifier OPE, a transistor TE, and a voltage divider circuit 67. Regulator 96 includes an operational amplifier OPE, a transistor TE, and a voltage divider circuit 97.

[0120] The operational amplifier OPE's non-inverting input terminal, serving as the first input terminal, receives the input voltage VRF, and its inverting input terminal, serving as the second input terminal, receives the feedback voltage VFB. The transistor TE is positioned between the node VDD (serving as the first power supply node) and the output node NE1 (serving as the output voltage VRG), and the output of the operational amplifier OPE is input to the gate of the transistor TE. Figure 16 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.

[0121] Voltage divider circuits 67 and 97 are 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 circuits 67 and 97 include 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.

[0122] according to Figure 16 The regulators 66 and 96 output a voltage VRG = {(RE1 + RE2) / RE2}VRF. The voltage VRG output by the regulator becomes, under the condition of regulator 66 in the reference voltage generation circuit 60... Figure 5 The reference power supply voltage VD becomes the power supply voltage VDL under the condition of the regulator 96 of the power supply circuit 90.

[0123] Figure 16 The regulators 66 and 96 correspond to Figure 9 , Figure 10 A regulator consisting of an Nch input stage and an Nch output stage. Figure 16 The differential pair transistors in the differential section of the operational amplifier OPE are N-type MOS transistors or npn bipolar transistors, enabling low noise. Furthermore, since the output transistor TE is also a depletion-mode N-type transistor, low noise is achieved. In this case, a P-type transistor can also be used as transistor TE. When transistor TE is P-type, Figure 16 The regulators 66 and 96 correspond to Figure 9 , Figure 10 A regulator consisting of an Nch input stage and a Pch output stage.

[0124] Figure 17 express Figure 11 Example of the circuit structure of the PTAT current source 56. Figure 17The current source 56 includes transistors TF1, TF2, and TF3, bipolar transistors TF4 and TF5, and resistor RF1, which constitute a current mirror circuit. The gates of P-type transistors TF1, TF2, and TF3 are connected together. The size ratio of transistor TF1 to transistor TF2 is, for example, 1:K. The base and collector of bipolar transistor TF4 are connected to node NF2, and the base of bipolar transistor TF5 is connected to node NF2. When the base-emitter voltages of npn bipolar transistors TF4 and TF5 are set to VBE1 and VBE2, respectively, the constants of the circuit elements are determined by a positive temperature characteristic ΔVBE = VBE1 - VBE2. Figure 17 The current source 56 can be used as a current source for PTAT.

[0125] Figure 18 This illustrates a structural example of the current source 58 for CTAT. Figure 18 The circuit includes P-type transistors TA9 and TA10 forming a current mirror circuit, N-type transistors TA7 and TA8 forming a current mirror circuit, and a resistor R4. When the gate-source voltage of the diode-connected transistor TA7 is set to VGS, the current flowing to resistor R4 is expressed as ICT = (VRF - VGS) / R4. Furthermore, by determining the circuit constant in a way that VRF - VGS has a negative temperature characteristic, a current source 58 for CTAT flowing through the current ICT can be realized.

[0126] As mentioned above, such as Figure 1 , Figure 2 As shown, the circuit device 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 that outputs a temperature compensation voltage VCP, the oscillation frequency of the oscillation signal, to the oscillation circuit 30 based on the temperature detection voltage VTS from the temperature detection circuit 50. Furthermore, the circuit device 20 includes: a power supply circuit 90 that generates a power supply voltage VDL for the temperature compensation circuit 40; and 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. Moreover, as in... Figure 12 As explained, the noise (A1) of the reference voltage VRC is smaller than the noise (A2, A3) of the supply voltage VDL. On the other hand, as in Figure 13 As explained, the temperature characteristics (B2, B3) of the power supply voltage VDL are flatter than the temperature characteristics (B1) of the reference voltage VRC.

[0127] In this way, by making the reference voltage VRC low-noise, the temperature compensation voltage VCP generated based on the reference voltage VRC also becomes low-noise. Therefore, it is possible to achieve low-noise oscillation signals generated based on the temperature compensation voltage VCP and clock signals based on the oscillation signals. Furthermore, by flattening the temperature characteristics of the power supply voltage VDL used for temperature compensation, stable operation of the temperature compensation circuit 40 can be achieved, and situations such as a narrowing of the voltage range of the temperature compensation voltage VCP can be prevented.

[0128] Furthermore, in this embodiment, the slope of the primary temperature characteristic of the power supply voltage VDL is less than the slope of the primary temperature characteristic of the reference voltage VRC. For example, the slope corresponding to the power supply voltage VDL... Figure 13 The slope of the primary temperature characteristic of voltage VRG shown in B2 and B3 is smaller than that used to generate the reference voltage VRC. Figure 13 The slope of the primary temperature characteristic of voltage VRG is shown in B1. Therefore, the slope of the primary temperature characteristic of power supply voltage VDL is less than the slope of the primary temperature characteristic of reference voltage VRC. In this way, by making the slope of the primary temperature characteristic of power supply voltage VDL smaller, the variation of power supply voltage VDL within the operating temperature range is reduced, thus enabling stable operation of temperature compensation circuit 40 and preventing the voltage range of temperature compensation voltage VCP from shrinking.

[0129] 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 a temperature detection voltage VTS. The current-to-voltage conversion circuit 46 has an operational amplifier OPD1 that operates based on a power supply voltage VDL for temperature compensation. The operational amplifier OPD1 converts the temperature compensation current ICP into a voltage, thereby generating a temperature compensation voltage VCP. Furthermore, a reference voltage VRC is input to, for example, a non-inverting input terminal, which serves as the first input terminal of the operational amplifier OPD1.

[0130] Thus, based on the power supply voltage VDL with flat temperature characteristics, the operational amplifier OPD1 of the current-to-voltage conversion circuit 46 can operate stably, preventing the voltage range of the temperature compensation voltage VCP from shrinking. Furthermore, since a low-noise reference voltage VRC is input to the first input terminal of the operational amplifier OPD1, the current-to-voltage conversion circuit 46 can generate a low-noise temperature compensation voltage VCP.

[0131] In addition, such as Figure 3 As shown, the current-to-voltage conversion circuit 46 includes a feedback resistor RD, which is disposed between the output terminal of the operational amplifier OPD1 and, for example, the inverting input terminal, which serves as the second input terminal. Furthermore, a temperature-compensated current ICP is input to the second input terminal of the operational amplifier OPD1.

[0132] In this way, the current-to-voltage conversion circuit 46 can use operational amplifier OPD1 and resistor RD to convert the temperature-compensated current ICP into a temperature-compensated voltage VCP. Furthermore, since operational amplifier OPD1 generates the temperature-compensated voltage VCP based on the reference voltage VRC input to the first input terminal, low-noise reduction of the temperature-compensated voltage VCP can be achieved.

[0133] In addition, such as Figure 6 , Figure 9 , Figure 11 As shown, the reference voltage generation circuit 60 has a reference circuit 62 that generates a BGR voltage (bandgap reference voltage) as a voltage VRF, and generates a reference voltage VRC based on the voltage VRF generated by the reference circuit 62.

[0134] In this way, a low-noise BGR voltage is generated by the reference circuit 62, and a reference voltage VRC is generated based on this low-noise BGR voltage, thus enabling the low-noise nature of the reference voltage VRC.

[0135] In addition, such as Figure 9 , Figure 11 As shown, the reference voltage generation circuit 60 has a regulator 66, which generates a reference voltage VRC based on a voltage VRF generated as the BGR voltage.

[0136] By setting up such a regulator 66, even when the output impedance of the reference circuit 62 is high, a reference voltage VRC can be generated based on the voltage VRF generated by the regulator 66 with low output impedance.

[0137] In addition, such as Figure 16 As shown, the regulator 66 of the reference voltage generation circuit 60 includes an operational amplifier OPE, a depletion-type N-type transistor TE, and a voltage divider circuit 67. The operational amplifier OPE inputs the voltage VRF, which serves as the BGR voltage, to a non-inverting input terminal (e.g., the first input terminal), and inputs the feedback voltage VFB to a second input terminal (e.g., the inverting input terminal). The depletion-type N-type transistor TE is located between the node VDD, which serves as the first power supply node, and the output node NE1, which serves as the regulation voltage VRG. The output of the operational amplifier OPE is input to the gate of the N-type transistor TE. Alternatively, as described above, the transistor TE can also be a P-type transistor. Furthermore, the voltage divider circuit 67 is located between the output node NE1 of the voltage VRG and the node VSS, which serves as the second power supply node, and outputs the voltage obtained by dividing the voltage VRG as the feedback voltage VFB. Figure 5 , Figure 11As shown, the voltage VRG generated by the regulator 66 of the reference voltage generation circuit 60 is used, for example, as the reference power supply voltage VD of the voltage generation circuit 68.

[0138] In this way, regulator 66 can adjust the power supply voltage VDD of the first power node based on voltage VRF, which serves as the BGR voltage, to generate voltage VRG as the adjustment voltage. Furthermore, reference voltage generation circuit 60 can use voltage VRG to generate reference voltage VRC.

[0139] Additionally, the reference voltage VRC exhibits a temperature characteristic with a first polarity within its operating temperature range. This first polarity is either positive or negative. For example, in... Figure 13 In B1, the temperature characteristic of the voltage VRG used to generate the reference voltage VRC becomes negative, and in this case, the temperature characteristic of the reference voltage VRC becomes negative.

[0140] In this way, even if the reference voltage VRC has a first-polarity temperature characteristic instead of a flat temperature characteristic, the first-polarity temperature characteristic of the reference voltage VRC can be offset by primary correction in the temperature compensation circuit 40, as described later. For example, by... Figure 3 The primary correction (primary compensation) in the primary correction circuit 43 can offset the temperature characteristics of the first polarity of the reference voltage VRC.

[0141] In addition, such as Figure 10 , Figure 11 As shown, the power supply circuit 90 includes a reference circuit 92 that generates a voltage VRF as a reference voltage for the power supply, and generates a power supply voltage VDD based on the voltage VRF. Furthermore, the reference circuit 92 generates a voltage obtained by adding a first voltage and a second voltage, and uses this as the reference voltage VRF for the power supply. This first voltage is generated by allowing a first current with a temperature characteristic having a first polarity to flow through a first resistor. Figure 14 , Figure 15 For example, the first current with a temperature characteristic of the first polarity is, for example, the current IPT of PTAT with a positive temperature characteristic. The first resistance is... Figure 14 resistor RC1 or Figure 15 The resistor RH1. Furthermore, the first voltage is generated by allowing current IPT to flow through resistor RC1 or resistor RH1. Additionally, in Figure 14 In this context, the second voltage is the gate-source voltage VGS of transistor TC2, which has its gate and drain connected. Additionally, in... Figure 15In this circuit, the second voltage is generated by allowing the first current IPT and the second current ICT to flow through the third resistor RH3. This second current has a temperature characteristic with a second polarity different from the first current. Furthermore, here, the first current IPT has a positive temperature characteristic, and the second current ICT has a negative temperature characteristic, but the positive and negative polarities can also be reversed.

[0142] In this way, a voltage VRF can be generated by adding a first voltage to the gate-source voltage VGS of transistor TC2, or a second voltage. The first voltage is generated by allowing current IPT to flow through resistor RC1 or resistor RH1, and the second voltage is generated by allowing currents IPT and ICT to flow through resistor RH3. Thus, a voltage VRF with a flat temperature characteristic as a power supply reference voltage is generated within the operating temperature range. Based on this voltage VRF, a power supply voltage VDL with a flat temperature characteristic can be generated.

[0143] In addition, such as Figure 10 , Figure 11 As shown, the power supply circuit 90 has a regulator 96 that generates a power supply voltage VDL based on a voltage VRF, which serves as a reference voltage for the power supply. For example, the regulator 96 regulates the power supply voltage VDD based on the voltage VRF to generate the power supply voltage VDL and supply it to the temperature compensation circuit 40.

[0144] By setting up such a regulator 96, even when the output impedance of the reference circuit 92 is high, the regulator 96 with low output impedance can generate and supply the power supply voltage VDL based on the voltage VRF.

[0145] In addition, such as Figure 16 As shown, the regulator 96 of the power supply circuit 90 includes an operational amplifier OPE, a depletion-type N-type transistor TE, and a voltage divider circuit 97. A reference voltage VRF, serving as the power supply voltage, is input to, for example, a non-inverting input terminal of the operational amplifier OPE, which serves as its first input terminal. A feedback voltage VFB is input to, for example, an inverting input terminal of the operational amplifier OPE, which serves as its second input terminal. The depletion-type N-type transistor TE is positioned between the node VDD, which serves as the first power supply node, and the output node NE1, which serves as the regulating voltage VRG. The output of the operational amplifier OPE is input to the gate of the N-type transistor TE. Alternatively, as described above, the transistor TE can also be a P-type transistor. Furthermore, the voltage divider circuit 97 is positioned between the output node NE1 of the voltage VRG and the node VSS, which serves as the second power supply node, and outputs the voltage obtained by dividing the voltage VRG as the feedback voltage VFB. Figure 11As shown, the voltage VRG generated by the regulator 96 of the power supply circuit 90 is supplied to the temperature compensation circuit 40 as the power supply voltage VDL.

[0146] In this way, the regulator 96 can adjust the power supply voltage VDD of the first power node based on the voltage VRF, which serves as the power supply reference voltage, and generate a voltage VRG as the adjustment voltage. Furthermore, the power supply circuit 90 can supply this voltage VRG as the power supply voltage VDL to the temperature compensation circuit 40.

[0147] In addition, Figure 14 In the circuit, reference circuit 92 includes transistor TC1, resistor RC1, and transistor TC2. Transistor TC1 is the first current source, and resistor RC1 is the first resistor.

[0148] Transistor TC1, serving as the first current source, is positioned between node VDD and node NC1, and a current IPT with a first polarity and temperature characteristic flows through it. Node VDD is the first power supply node, and node NC1 is the first node. Furthermore, the current IPT is the first current, and its first polarity and temperature characteristic are, for example, positive.

[0149] A resistor RC1, acting as the first resistor, is connected in series with a transistor TC1, acting as the first current source, between the VDD node and the NC1 node. A transistor TC2 is positioned between the NC1 and VSS nodes, with its gate and drain connected to the NC1 node. The VSS node is the second power supply node. Furthermore, a reference voltage VRF, serving as the power supply voltage, is output from the output node NCQ between the transistor TC1 and the resistor RC1.

[0150] According to the reference circuit 92 configured in this way, when the gate-source voltage of transistor TC2 is set to VGS and the resistance value of resistor RC1 is represented by the same reference numeral RC1, a voltage VRF = VGS + RC1·IPT is output from the output node NCQ. Therefore, for example, by adjusting the resistance value of resistor RC1, a voltage VRF with a flat temperature characteristic can be generated based on the temperature characteristics of the first polarity of current IPT and the temperature characteristics of the second polarity of voltage VGS.

[0151] In addition, Figure 15 In the reference circuit 92, transistor TH1, resistor RH1, transistor TH2, resistor RH2, and resistor RH3 are included. Transistor TH1 is the first current source, resistor RH1 is the first resistor, transistor TH2 is the second current source, resistor RH2 is the second resistor, and resistor RH3 is the third resistor.

[0152] Transistor TH1, serving as the first current source, is positioned between node VDD and node NH1, and a current IPT with a first polarity temperature characteristic flows through it. This first polarity temperature characteristic is, for example, a positive temperature characteristic. Node NH1 is the first node. Furthermore, the current IPT is the first current. Additionally, resistor RH1, serving as the first resistor, is connected in series with transistor TH1, serving as the first current source, between node VDD and node NH1.

[0153] Transistor TH2, serving as a second current source, is positioned between nodes NH1 and VDD, and a current ICT flows through it, exhibiting a second polarity with a temperature characteristic different from the first polarity. This second polarity temperature characteristic is, for example, negative. Furthermore, the current ICT is a second current. Additionally, resistor RH2, serving as a second resistor, is connected in series with transistor TH2, which serves as the second current source, between nodes NH1 and VDD.

[0154] Additionally, resistor RH3 is positioned between node NH1 and VSS, through which currents IPT and ICT flow. Furthermore, voltage VRF, serving as the power supply reference voltage, is output from output node NHQ between transistor TH1 and resistor RH1.

[0155] In the reference circuit 92 configured as described above, with the resistance values ​​of resistors RH1, RH2, and RH3 represented by the same reference numerals, the voltage VRF = RH1·IPT + RH3·(IPT + ICT) is output from the output node NHQ between transistor TH1 and resistor RH1. Furthermore, since current IPT has a temperature characteristic with a first polarity, and current ICT has a temperature characteristic with a second polarity different from the first polarity, a voltage VRF with a flat temperature characteristic can be generated by adjusting the resistance value of resistor RH1.

[0156] 3.1 calibration

[0157] In this embodiment, the reference voltage VRC is as follows: Figure 13 As described in B1, 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.

[0158] 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 (4).

[0159]

Mathematical Expression 4

[0160]

[0161] 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 (5).

[0162]

Mathematical Expression 5

[0163]

[0164] Furthermore, when the above equation (5) is substituted into the above equation (4), the temperature compensation voltage VCP can be expressed as shown in the following equation (6).

[0165]

Mathematical Expression 6

[0166]

[0167] Therefore, when c in equation (5) is not 0 and the reference voltage VRC has a primary temperature characteristic of ct+d, it can be seen from equation (6) that by performing a primary gain adjustment to correct the resistance value of resistor RD3 in the primary correction circuit 43, the temperature compensation voltage VCP can be adjusted. Therefore, 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 compensate for the primary temperature characteristic of the reference voltage VRC.

[0168] 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 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; a power supply circuit that generates a power supply voltage for the temperature compensation 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 noise of the reference voltage is lower than that of the power supply voltage, and the temperature characteristic of the power supply voltage is flatter than that of the reference voltage.

[0169] According to this embodiment, the reference voltage becomes low-noise, and therefore, the temperature compensation voltage generated based on the reference voltage also becomes low-noise, enabling the noise reduction of the oscillation signal generated based on the temperature compensation voltage. Furthermore, by flattening the temperature characteristics of the power supply voltage used for temperature compensation, stable operation of the temperature compensation circuit can be achieved.

[0170] In addition, in this embodiment, the slope of the primary temperature characteristic of the power supply voltage may be less than the slope of the primary temperature characteristic of the reference voltage.

[0171] In this way, the fluctuation of the power supply voltage for temperature compensation within the operating temperature range is reduced, enabling the temperature compensation circuit to operate stably.

[0172] 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 operates based on a power supply voltage for temperature compensation, using the operational amplifier to convert the temperature compensation current into a voltage, thereby generating a temperature compensation voltage. Furthermore, a reference voltage can be input to the first input terminal of the operational amplifier.

[0173] Thus, based on the power supply voltage with flat temperature characteristics, the operational amplifier of the current-to-voltage conversion circuit can operate stably. Furthermore, since a low-noise reference voltage is input to the first input terminal of the operational amplifier, a low-noise temperature-compensated voltage can be generated.

[0174] Alternatively, in this embodiment, the current-to-voltage conversion circuit may include a feedback resistor disposed between the output terminal and the second input terminal of the operational amplifier, to input a temperature-compensated current to the second input terminal of the operational amplifier.

[0175] In this way, the temperature compensation current can be converted into a temperature compensation voltage using an operational amplifier and a feedback resistor. The temperature compensation voltage is generated based on the reference voltage input to the first input terminal of the operational amplifier, thus enabling the temperature compensation voltage to be low-noise.

[0176] Alternatively, in this embodiment, the reference voltage generation circuit may have a reference circuit for generating a bandgap reference voltage, and the reference voltage may be generated based on the bandgap reference voltage generated by the reference circuit.

[0177] Thus, since the reference voltage is generated based on a low-noise bandgap reference voltage, it is possible to achieve low-noise reference voltage.

[0178] Alternatively, in this embodiment, the reference voltage generation circuit may have a regulator that generates a reference voltage based on a voltage generated from a bandgap reference voltage.

[0179] In this way, even when the output impedance of the reference circuit is high, a reference voltage can be generated based on the voltage generated by the regulator with a low output impedance.

[0180] In addition, in this embodiment, the regulator may also include: an operational amplifier whose first input terminal receives a bandgap reference voltage and whose second input terminal receives a feedback voltage; and a depletion-type N-type transistor or P-type transistor disposed between the first power supply node and the output node of the regulated voltage, with its gate input to the output of the operational amplifier. Alternatively, the regulator may also include a voltage divider circuit disposed between the output node of the regulated voltage and the second power supply node, outputting a voltage obtained by dividing the regulated voltage as the feedback voltage.

[0181] In this way, by adjusting the power supply voltage of the first power node based on the bandgap reference voltage, an regulated voltage can be generated, and a reference voltage can be generated using the regulated voltage.

[0182] In addition, in this embodiment, the reference voltage may also have a temperature characteristic with a first polarity within the operating temperature range.

[0183] In this way, even if the reference voltage has a temperature characteristic of the first polarity, the temperature characteristic of the first polarity of the reference voltage can be offset by the first correction in the temperature compensation circuit.

[0184] In this embodiment, the power supply circuit may also include a reference circuit for generating a power supply reference voltage, based on which the power supply voltage is generated. Furthermore, the reference circuit may also generate a voltage obtained by adding a first voltage and a second voltage as the power supply reference voltage, wherein the first voltage is generated by flowing a first current with a first polarity and temperature characteristics through a first resistor. The second voltage may also be the gate-source voltage of a transistor with its gate and drain connected, or a voltage generated by flowing a first current and a second current through a third resistor, wherein the second current has a second polarity and temperature characteristics different from the first polarity.

[0185] Thus, a first voltage is generated by allowing a first current with a first temperature characteristic of a first polarity to flow through a first resistor. Alternatively, a second voltage is generated by generating the gate-source voltage of a transistor with its gate and drain connected, or by allowing the first current and a second current with a second temperature characteristic of a second polarity to flow through a third resistor. Furthermore, a voltage obtained by adding the first and second voltages can be generated as a reference voltage for power supply.

[0186] Alternatively, in this embodiment, the power supply circuit may have a regulator that generates a power supply voltage based on a reference voltage for the power supply.

[0187] In this way, even when the output impedance of the reference circuit is high, the regulator with low output impedance can generate the power supply voltage based on the power supply reference voltage.

[0188] In addition, in this embodiment, the regulator may also include: an operational amplifier whose first input terminal receives a reference voltage for the power supply and whose second input terminal receives a feedback voltage; and a depletion-type N-type transistor or P-type transistor disposed between the first power supply node and the output node of the regulated voltage, with its gate input to the output of the operational amplifier. Alternatively, the regulator may also include a voltage divider circuit disposed between the output node of the regulated voltage and the second power supply node, outputting a voltage obtained by dividing the regulated voltage as the feedback voltage.

[0189] In this way, by adjusting the power supply voltage of the first power node based on the power supply reference voltage, an regulated voltage is generated, which can be supplied to the temperature compensation circuit as the power supply voltage.

[0190] In this embodiment, the power supply circuit may also include a reference circuit for generating a power supply reference voltage, based on which the power supply voltage is generated. The reference circuit may also include: a first current source disposed between the first power node and the second power node, through which a first current having a first polarity and temperature characteristic flows; and a first resistor connected in series with the first current source between the first power node and the second power node. Furthermore, the reference circuit may include a transistor disposed between the first node and the second power node, with its gate and drain connected to the first node. Moreover, the power supply reference voltage can be output from the output node between the first current source and the first resistor.

[0191] In this way, by utilizing the temperature characteristics of the first polarity of the first current and the temperature characteristics of the second polarity of the gate-source voltage of the transistor connected to the gate and drain, a power supply reference voltage with flat temperature characteristics can be generated.

[0192] In this embodiment, the power supply circuit may also include a reference circuit for generating a power supply reference voltage, based on which the power supply voltage is generated. The reference circuit may also include: a first current source disposed between the first power node and the first node, through which a first current with a first polarity and temperature characteristics flows; and a first resistor connected in series with the first current source between the first power node and the first node. Furthermore, the reference circuit may include: a second current source disposed between the first power node and the first node, through which a second current with a second polarity and temperature characteristics different from the first polarity flows; and a second resistor connected in series with the second current source between the first power node and the first node. Additionally, the reference circuit may include a third resistor disposed between the first node and the second power node, through which the first current and the second current flow. Moreover, the power supply reference voltage can be output from the output node between the first current source and the first resistor.

[0193] In this way, the first current of the first polarity temperature characteristic flows to the first resistor, and the first current of the first polarity temperature characteristic and the second current of the second polarity temperature characteristic flow to the third resistor. Thus, a power supply reference voltage with a flat temperature characteristic can be output from the output node.

[0194] Furthermore, the oscillator of this embodiment includes the circuit arrangement and oscillator described above.

[0195] 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 that is 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, which 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; A power supply circuit that generates the power supply voltage for the temperature compensation 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 noise of the reference voltage is less than that of the power supply voltage. The temperature characteristic of the power supply voltage is flatter than that of the reference voltage.

2. The circuit device according to claim 1, characterized in that, The slope of the primary temperature characteristic of the power supply voltage is less than the slope of the primary temperature characteristic of the reference voltage.

3. 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 has an operational amplifier that operates based on the power supply voltage for temperature compensation. The operational amplifier is used to convert the temperature-compensating current into a voltage to generate the temperature-compensating voltage. The reference voltage is input to the first input terminal of the operational amplifier.

4. The circuit device according to claim 3, characterized in that, The current-to-voltage conversion circuit includes a feedback resistor, which is positioned between the output terminal and the second input terminal of the operational amplifier. The temperature compensation current is input to the second input terminal of the operational amplifier.

5. The circuit device according to claim 1, characterized in that, The reference voltage generation circuit has a reference circuit for generating a bandgap reference voltage, and the reference voltage is generated based on the bandgap reference voltage generated by the reference circuit.

6. The circuit device according to claim 5, characterized in that, The reference voltage generation circuit has a regulator that generates the reference voltage based on the voltage generated by the regulator based on the bandgap reference voltage.

7. The circuit device according to claim 6, characterized in that, The regulator includes: An operational amplifier, wherein the bandgap reference voltage is input to its first input terminal and the feedback voltage is input to its second input terminal; A depletion-type N-type transistor or P-type transistor is disposed between a first power supply node and an output node with regulated voltage, and its gate is input to the output of the operational amplifier; as well as A voltage divider circuit is disposed between the output node of the regulated voltage and the second power supply node, and outputs a voltage obtained by dividing the regulated voltage as the feedback voltage.

8. The circuit device according to claim 5, characterized in that, The reference voltage has a temperature characteristic with a first polarity within its operating temperature range.

9. The circuit device according to claim 1, characterized in that, The power supply circuit includes a reference circuit for generating a reference voltage for the power supply, and the power supply voltage is generated based on the reference voltage. The reference circuit generates a voltage obtained by adding a first voltage and a second voltage as a reference voltage for the power supply. The first voltage is generated by allowing a first current with a first polarity and temperature characteristics to flow through a first resistor. The second voltage is the gate-source voltage of a transistor with its gate and drain connected, or the voltage generated by allowing the first current and a second current having a temperature characteristic with a second polarity different from the first polarity to flow through a third resistor.

10. The circuit device according to claim 9, characterized in that, The power supply circuit has a regulator that generates the power supply voltage based on a reference voltage for the power supply.

11. The circuit device according to claim 10, characterized in that, The regulator includes: An operational amplifier, wherein a reference voltage for the power supply is input to its first input terminal and a feedback voltage is input to its second input terminal; A depletion-type N-type transistor or P-type transistor is disposed between a first power supply node and an output node with regulated voltage, and its gate is input to the output of the operational amplifier; as well as A voltage divider circuit is disposed between the output node of the regulated voltage and the second power supply node, and outputs a voltage obtained by dividing the regulated voltage as the feedback voltage.

12. The circuit device according to claim 1, characterized in that, The power supply circuit includes a reference circuit for generating a reference voltage for the power supply, and the power supply voltage is generated based on the reference voltage. The reference circuit includes: A first current source is disposed between a first power node and a first node, through which a first current with a temperature characteristic having a first polarity flows; A first resistor is connected in series with the first current source and disposed between the first power supply node and the first node; as well as A transistor is disposed between the first node and the second power node, with its gate and drain connected to the first node. The power supply is output from the output node between the first current source and the first resistor using a reference voltage.

13. The circuit device according to claim 1, characterized in that, The power supply circuit includes a reference circuit that generates a reference voltage for power supply, and the power supply voltage is generated based on the reference voltage. The reference circuit includes: A first current source is disposed between a first power node and a first node, through which a first current with a temperature characteristic having a first polarity flows; A first resistor is connected in series with the first current source and disposed between the first power supply node and the first node; A second current source is disposed between the first power node and the first node, through which a second current with a second polarity different from the first polarity flows; The second resistor is connected in series with the second current source and is disposed between the first power node and the first node; as well as A third resistor is disposed between the first node and the second power supply node, through which the first current and the second current flow. The power supply is output from the output node between the first current source and the first resistor using a reference voltage.

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

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