Voltage-controlled oscillator circuits and electronic equipment

Abstract

A voltage-controlled oscillation circuit and electronic device, the circuit comprising: an oscillation module, responsive to a first control signal and a second control signal, for outputting a target oscillation signal according to the first control signal and the second control signal; a feedback module, responsive to the first control signal and a reference voltage signal, for adjusting the second control signal according to the first control signal and the reference voltage signal after the target oscillation signal is locked to keep the frequency of the target oscillation signal stable. The voltage-controlled oscillation circuit of the present application introduces negative feedback into the first control signal through the feedback module, and adopts a closed-loop feedback method to perform closed-loop automatic temperature compensation on the circuit, thereby improving the accuracy of temperature compensation.

Description

Technical Field

[0001] The present application relates to the field of electronic technology, and in particular to a voltage-controlled oscillator circuit and an electronic device. Background Art

[0002] A voltage-controlled oscillator circuit is an oscillator circuit whose output frequency is controlled by the input voltage. The output frequency of the voltage-controlled oscillator circuit is a function of the input signal voltage. Voltage-controlled oscillator circuits are widely used, for example, to generate clocks in various communication systems, phase-locked loops (PLLs) in various high-speed data transmission systems, etc.

[0003] Voltage controlled oscillator circuits generally use capacitor arrays to cover a wide frequency range, such as Figure 1 When powered on, the external clock frequency or data rate is locked by adjusting the capacitor array (Cap band). After locking, if the external clock frequency, phase or data rate, phase changes, the variable capacitor formed by the variable capacitance diode Varactor can be used to adjust the lock.

[0004] Since the voltage-controlled oscillator circuit is affected by temperature, when the frequency of the output signal changes too much with temperature, the adjustable range of the varactor diode is limited, which may cause the phase-locked loop of the application to lose lock, which is not allowed in some applications. Even if the phase-locked loop does not lose lock, the adjustment capability of the varactor diode is used to compensate for the change of the frequency of the output signal of the voltage-controlled oscillator circuit with temperature, thereby weakening the ability of the voltage-controlled oscillator circuit to cope with the change of the input clock or data frequency and phase. Summary of the invention

[0005] In view of this, the present application provides a voltage-controlled oscillation circuit and an electronic device to solve the problem that the frequency of the output signal of the existing voltage-controlled oscillation circuit varies with temperature.

[0006] The present application provides a voltage-controlled oscillation circuit, comprising: an oscillation module, responsive to a first control signal and a second control signal, for outputting a target oscillation signal according to the first control signal and the second control signal; a feedback module, responsive to the first control signal and a reference voltage signal, for adjusting the second control signal according to the first control signal and the reference voltage signal after the target oscillation signal is locked to keep the frequency of the target oscillation signal stable.

[0007] Optionally, the oscillation module includes an impedance unit, a first oscillation unit and a second oscillation unit; the first end of the impedance unit is respectively connected to the first end of the first oscillation unit and the first end of the second oscillation unit, and serves as the first output end of the oscillation module, and the second end of the impedance unit is respectively connected to the second end of the first oscillation unit and the second end of the second oscillation unit, and serves as the second output end of the oscillation module; the third end of the first oscillation unit responds to the first control signal, and the third end of the second oscillation unit responds to the second control signal to adjust the signal frequency output by the oscillation module; the first output end and the second output end are used to output the adjusted target oscillation signal.

[0008] Optionally, the feedback module includes a comparison unit; the first input end of the comparison unit is used to obtain the reference voltage, the second input end is used to obtain the first control signal, and the output end is used to output the second control signal; the second control signal is used to control the capacitance value of the second oscillation unit according to an external input signal to output the target oscillation signal; the first control signal is used to feed back to the comparison unit when the target oscillation signal generates an offset to adjust the value of the second control signal and eliminate the offset.

[0009] Optionally, the comparison unit is an operational amplifier or a comparator.

[0010] Optionally, the oscillation module further includes a negative resistance unit; the negative resistance unit is connected between the first oscillation unit and a power supply, and is used to provide energy to the oscillation module.

[0011] Optionally, the negative resistance unit includes a first transistor and a second transistor, the first end of the first transistor and the first end of the second transistor are connected to a voltage source, the second end of the first transistor and the third end of the second transistor are connected to the second output end of the oscillation module, and the third end of the first transistor and the second end of the second transistor are connected to the first output end of the oscillation module.

[0012] Optionally, the negative resistance unit further includes a third transistor and a fourth transistor.

[0013] The first end of the third transistor and the first end of the fourth transistor are connected to the ground, the second end of the third transistor and the third end of the fourth transistor are connected to the second output end of the oscillation module, and the third end of the third transistor and the second end of the fourth transistor are connected to the first output end of the oscillation module.

[0014] Optionally, when the comparison unit is an operational amplifier, the inverting input terminal of the operational amplifier is used to input the reference voltage signal, the non-inverting input terminal is used to input the first control signal, and the output terminal is used to output the second control signal; the value of the first control signal at power-on locking is equal to the value after eliminating the offset.

[0015] Optionally, it also includes a capacitor; one end of the capacitor is connected to the output end of the operational amplifier, and the other end is grounded.

[0016] Optionally, the oscillation module further includes a capacitor array, one end of the capacitor array is connected to the first output end, and the other end is connected to the second output end, the impedance unit is an inductor, one end of the inductor is connected to the first output end, and the other end is connected to the second output end; after eliminating the offset, the frequency Fin of the target oscillation signal satisfies the following formula:

[0017]

[0018] Wherein, Fin is the frequency of the target oscillation signal, L ind is the inductance of the inductor, K1 and K2 are proportional constants, K3 is the temperature coefficient, T is the temperature, ΔT is the temperature change, V ref is the reference voltage, V ctrl2 is the second control signal, ΔV ctrl2 is the second control signal offset, n*C band is the capacitance of the capacitor array, C C is the total capacitance of the first oscillation unit and the second oscillation unit.

[0019] The present application also provides an electronic device, comprising the voltage-controlled oscillation circuit.

[0020] The voltage-controlled oscillation circuit of the present application introduces the first control signal into negative feedback through a feedback module, and adopts a closed-loop feedback method to perform closed-loop automatic temperature compensation on the circuit, thereby improving the accuracy of temperature compensation.

[0021] Furthermore, through the operational amplifier, the inverting input terminal of the operational amplifier is used to input a reference voltage signal, the non-inverting input terminal is used to input a first control signal, and the output terminal is used to output a second control signal; the value of the first control signal after eliminating the offset is equal to the value at the power-on lock. Since the first control signal is used to adjust the capacitance in the first oscillation unit to achieve fine-tuning lock when the external clock frequency, phase or data rate, phase changes, when the temperature changes, the operational amplifier adjusts the value of the second control signal after amplifying the error between the first control signal and the reference voltage value to adjust the capacitance of the second oscillation unit, while the capacitance of the first oscillation unit remains unchanged, that is, the capacitance of the first oscillation unit will not be used to compensate for the change in the frequency of the output signal of the voltage-controlled oscillation circuit with temperature, so it will not weaken the ability of the voltage-controlled oscillation circuit to cope with changes in the input clock or data frequency and phase. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For those skilled in the art, other drawings can be obtained based on these drawings without creative work.

[0023] Figure 1 This is a schematic diagram of the structure of the existing voltage-controlled oscillation circuit;

[0024] Figure 2 A schematic diagram of the structure of a voltage-controlled oscillator circuit according to an embodiment of the present application;

[0025] Figure 3 A schematic diagram of the structure of a voltage-controlled oscillator circuit according to an embodiment of the present application;

[0026] Figure 4 A circuit diagram of a voltage-controlled oscillator circuit according to an embodiment of the present application;

[0027] Figure 5 A circuit diagram of an operational amplifier according to an embodiment of the present application;

[0028] Figure 6 FIG. 4 is a circuit diagram of an operational amplifier according to an embodiment of the present application.

[0029] The above drawings have shown clear embodiments of the present application, which will be described in more detail later. These drawings and text descriptions are not intended to limit the scope of the present application in any way, but to illustrate the concept of the present application to those skilled in the art by referring to specific embodiments. DETAILED DESCRIPTION

[0030] The technical solutions in the embodiments of the present application are clearly and completely described below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present application. In the absence of conflict, the following embodiments and their technical features can be combined with each other.

[0031] In order to solve the problem that the voltage-controlled oscillation circuit is affected by temperature, when the output signal frequency changes too much with temperature, the adjustable range of the varactor diode is limited, and the applied phase-locked loop may lose lock, the present application provides a voltage-controlled oscillation circuit.

[0032] See also Figure 2 , a schematic diagram of the structure of the voltage-controlled oscillation circuit of this embodiment.

[0033] Figure 2 The voltage-controlled oscillator circuit in the embodiment uses a current meter (Itemp) with a temperature coefficient and a variable capacitance diode Varacctor2 to perform temperature compensation on the voltage-controlled oscillator circuit. The specific working principle of the circuit is as follows:

[0034] When the circuit is powered on, the external clock frequency or data rate is locked by adjusting the capacitor array (Cap band). After locking, if the external clock frequency, phase or data rate, phase changes, it can be adjusted and locked through the varactor diodes Varactor1 and Varactor2. When the temperature changes, Itemp will generate a current that changes with the temperature. This current flows through the resistor R1 and generates a voltage that changes with the temperature. The voltage is used to adjust the capacitance of the varactor diode Varactor2, thereby adjusting the frequency of the output signal of the voltage-controlled oscillator circuit to achieve the purpose of temperature compensation.

[0035] but, Figure 2 The voltage-controlled oscillator circuit in the circuit uses an open-loop compensation method, so it is impossible to accurately know whether the voltage-controlled oscillator circuit has obtained appropriate temperature compensation. If the frequency of the voltage-controlled oscillator circuit changes positively with temperature, and the frequency compensation provided by the compensation circuit also changes positively with temperature, the degree of frequency change with temperature will not only not decrease, but will become more dramatic. In addition, Figure 2 The adjustment capability of the varactor 2 part is also used to compensate for the change of the output signal frequency of the voltage-controlled oscillator circuit with temperature, thereby weakening the ability of the voltage-controlled oscillator circuit to cope with the change of input clock or data frequency and phase.

[0036] To further solve Figure 2The voltage-controlled oscillation circuit in the embodiment adopts an open-loop compensation method, and it is impossible to accurately know whether the voltage-controlled oscillation circuit obtains appropriate temperature compensation, and the compensation accuracy is low. The present application provides a voltage-controlled oscillation circuit.

[0037] See also Figure 3 , a schematic diagram of the structure of a voltage-controlled oscillator circuit according to an embodiment of the present application.

[0038] The voltage-controlled oscillation circuit of this embodiment includes: an oscillation module 1 and a feedback module 2 .

[0039] Oscillation module 1, in response to a first control signal V ctrl1 and the second control signal V ctrl2 , and according to the first control signal V ctrl1 and the second control signal V ctrl2 Output target oscillation signal Vout. The oscillation module 1 can be a passive energy storage device, which can also be called a resonant circuit or a resonator. The oscillation module 1 includes an LC (inductance and capacitance) oscillation module, an RC (resistance and capacitance) oscillation module, and a crystal oscillation module. When the oscillation module 1 is an LC oscillation module, it includes an inductor element and a capacitor element, and its inductance value and capacitance value basically determine the output signal frequency of the oscillation circuit.

[0040] Temperature compensation is very important for voltage-controlled oscillator circuits, because large temperature changes may cause the phase-locked loop (PLL) to lose lock. In order to achieve temperature compensation for the voltage-controlled oscillator circuit and improve the stability of the output frequency of the voltage-controlled oscillator circuit with temperature changes, the first control signal V ctrl1 and the second control signal V ctrl2 The frequency of the output target oscillation signal Vout is controlled to achieve temperature compensation. In other optional implementations, the oscillation module 1 can also achieve output frequency changes of the voltage-controlled oscillation circuit due to other reasons, such as noise.

[0041] See also Figure 4 , a circuit diagram of a voltage-controlled oscillator circuit according to an embodiment of the present application.

[0042] In the voltage-controlled oscillation circuit of this embodiment, the oscillation module includes an impedance unit 10 , a first oscillation unit 11 and a second oscillation unit 12 .

[0043] The first end of the impedance unit 10 is respectively connected to the first end of the first oscillation unit 11 and the first end of the second oscillation unit 12, and serves as the first output end VOL of the oscillation module. The second end of the impedance unit 10 is respectively connected to the second end of the first oscillation unit 11 and the second end of the second oscillation unit 12, and serves as the second output end VOR of the oscillation module.

[0044] In this embodiment, the impedance unit 10 includes an inductor Ind, one end of which is connected to the first output terminal VOL, and the other end of which is connected to the second output terminal VOR. In other optional embodiments, the impedance unit 10 may include any number of inductors or resistors, such as a number of inductors connected in series or in parallel, or a resistor, or a number of resistors connected in series or in parallel. In some embodiments, when the impedance unit 10 is an inductor and the first oscillation unit 11 and the second oscillation unit 12 are capacitors, the oscillation module constitutes an LC oscillation module; in other embodiments, when the impedance unit 10 is a resistor and the first oscillation unit 11 and the second oscillation unit 12 are capacitors, the oscillation module constitutes an RC oscillation module. Both the LC oscillation module and the RC oscillation module are used to output a target oscillation signal of a fixed frequency.

[0045] In this embodiment, the first oscillating unit 11 includes a first varactor diode Var1 and a second varactor diode Var2; the cathode of the first varactor diode Var1 is connected to the cathode of the second varactor diode Var2 and is used to receive the first control signal V ctrl1 , the anode of the first varactor diode Var1 is connected to the first output terminal VOL of the oscillation module, and the anode of the second varactor diode Var2 is connected to the second output terminal VOR of the oscillation module. In other embodiments, the first oscillation unit 11 may also include one or three or more varactor diodes.

[0046] The second oscillation unit 12 includes a third varactor diode Var3 and a fourth varactor diode Var4; the cathode of the third varactor diode Var3 is connected to the cathode of the fourth varactor diode Var4 and is used to receive the second control signal V ctrl2 The anode of the third varactor diode Var3 is connected to the first output terminal VOL of the oscillation module, and the anode of the fourth varactor diode Var4 is connected to the second output terminal VOR of the oscillation module. In other embodiments, the second oscillation unit 12 may also include one or three or more varactor diodes.

[0047] In the voltage-controlled oscillation circuit of the present embodiment, the oscillation module further includes a capacitor array 13, one end of the capacitor array 13 is connected to the first output terminal VOL, and the other end is connected to the second output terminal VOR. The capacitor array 13 includes a plurality of capacitors with fixed capacitance values, for example, 6 capacitors, capacitors Cb1, Cb2, Cb3, Cb4, Cb5 and Cb6. One end of the capacitors Cb1 and Cb2 are connected to the first output terminal VOL and the second output terminal VOR respectively, and the other end is connected through a control switch K1. Similarly, capacitors Cb3 and Cb4 are connected through a control switch K2, and capacitors Cb5 and Cb6 are connected through a control switch K3. The control switches K1, K2 and K3 are respectively controlled to be turned on or off according to the value of the switch control signal Csw<2:0>. The value of the switch control signal Csw<2:0> can be generated by an external controller. When the voltage-controlled oscillation circuit is powered on, the value of the appropriate switch control signal Csw<2:0> is selected according to the frequency of the external input signal to lock the external clock frequency or data rate. After locking, if the external clock frequency, phase or data rate, phase changes, the variable capacitance diode can be used to adjust the lock. At present, most application environments require the frequency source to cover a wider frequency range. In order to further expand the frequency range of the output signal of the voltage-controlled oscillation circuit, a capacitor array 13 is added. The capacitor array Capband is composed of capacitors with fixed capacitance values ​​and is switched by adding a switch tube through the switch control signal Csw<2:0> to achieve frequency band selection within a wider frequency range.

[0048] In other optional embodiments, the first oscillation unit 11 and the second oscillation unit 12 may further include other variable capacitance elements, such as a variable capacitance array. The correspondence between the first control signal and the second control signal and the variable capacitance array may be controlled by a controller, and the oscillation capacitance value may be adjusted by using a feedback module in combination with the controller.

[0049] The first output terminal VOL and the second output terminal VOR of the oscillation module are used to output the adjusted target oscillation signal. The first output terminal VOL and the second output terminal VOR are differential signals to improve the signal anti-interference ability.

[0050] The oscillation module 1 further includes a negative resistance unit; the negative resistance unit is connected between the first oscillation unit 11 and the power source S, and is used to provide energy to the oscillation module 1 .

[0051] Optionally, the negative resistance unit may include a first transistor and a second transistor, which form a cross-coupled pair of transistors, which can provide a negative resistance for the oscillation circuit. When current flows through the negative resistance, the voltage on it decreases. The negative resistance is an energy source that can compensate for the energy loss in the oscillation module. The first transistor and the second transistor can be NMOS transistors or PMOS transistors. In other optional embodiments, the number of cross-coupled pairs of transistors formed by the first transistor and the second transistor can be one or more.

[0052] like Figure 4 In the embodiment, the negative resistance unit includes two cross-coupled transistor pairs, namely a cross-coupled transistor pair 141 and a cross-coupled transistor pair 142 .

[0053] The cross-coupled transistor pair 141 includes a first transistor NM1 and a second transistor NM2, both of which are NMOS transistors, a source of the first transistor NM1 and a source of the second transistor NM2 are connected to one end of a current source S, the other end of the current source S is grounded, a gate of the first transistor NM1 and a drain of the second transistor NM2 are connected to a second output end VOR of the oscillation module, and a drain of the first transistor NM1 and a gate of the second transistor NM2 are connected to a first output end VOL of the oscillation module.

[0054] The cross-coupled transistor pair 142 includes a third transistor PM1 and a fourth transistor PM2, both of which are PMOS transistors, a source of the third transistor PM1 and a source of the fourth transistor PM2 are connected to a power supply voltage VCC, a gate of the third transistor PM1 and a drain of the fourth transistor PM2 are connected to a second output terminal VOR of the oscillation module, and a drain of the third transistor PM1 and a gate of the fourth transistor PM2 are connected to a first output terminal VOL of the oscillation module.

[0055] In other embodiments, the first transistor NM1 , the second transistor NM2 , the third transistor PM1 , and the fourth transistor PM2 may be other types of transistors, such as triodes, thyristors, and the like.

[0056] The first transistor NM1, the second transistor NM2, the third transistor PM1 and the fourth transistor PM2 are transistors of the same type, which can make the target oscillation signal outputted finally more symmetrical, thereby reducing the phase noise of the circuit, thereby achieving low phase noise of the outputted target oscillation signal. By adding the third transistor PM1 and the fourth transistor PM2, a negative resistor can also be added, and the negative resistor is an energy source, which can further improve the energy supply capacity.

[0057] As can be seen from the above discussion, when the voltage-controlled oscillation circuit is powered on and locked, the phase-locked loop locks the input clock signal by selecting a suitable capacitor array value. After locking, when the input clock signal or data frequency and phase change, the capacitance values ​​of the first varactor diode Var1 and the second varactor diode Var2 are fine-tuned by controlling the value of the first control signal Vcrrl1 to re-lock. When the temperature changes, the capacitance values ​​of the first varactor diode Var1 and the second varactor diode Var2 are also fine-tuned by controlling the value of the first control signal Vcrrl1 to re-lock. Since the capacitance values ​​of the first varactor diode Var1 and the second varactor diode Var2 are limited, inaccurate temperature compensation may occur, causing the phase-locked loop to lose lock. In addition, the adjustment capacity of part of the first varactor diode Var1 and the second varactor diode Var2 is used to compensate for the change of the frequency of the voltage-controlled oscillation circuit with temperature, thereby weakening the ability to cope with the change of the input clock signal or data frequency and phase.

[0058] In order to prevent the adjustment capability of the first varactor diode Var1 and the second varactor diode Var2 from being used to compensate for the frequency change of the voltage-controlled oscillator circuit with temperature, the present application adopts Figure 3 The feedback module 2 in the circuit, in response to the first control signal and the reference voltage signal, is used to adjust the second control signal according to the first control signal and the reference voltage signal after the target oscillation signal is locked to keep the frequency of the target oscillation signal stable. Since only the second control signal is used to control the corresponding varactor diode for temperature compensation, the first varactor diode Var1 and the second varactor diode Var2 corresponding to the first control signal are not used for temperature compensation, so it is avoided that the adjustment capacity of part of the first varactor diode Var1 and the second varactor diode Var2 is used to compensate for the change of the frequency of the voltage-controlled oscillation circuit with temperature. For example, the first control signal and the second control signal are set to be equal to the reference voltage when the power is locked. For the comparator implementation case, when the temperature changes, the first control signal is compared with the reference voltage, and the second control signal value is gradually adjusted according to the level of the output voltage. The voltage value of this second control signal is discrete. For the operational amplifier implementation case, the first control signal and the second control signal are set to be linearly related to the reference voltage. When the temperature changes, the first control signal is compared with the reference voltage, and the second control signal value is adjusted according to the difference between the two. The voltage value of this second control signal is a continuous value. When the temperature changes, the operational amplifier adjusts the value of the second control signal by amplifying the error between the first control signal and the reference voltage value to adjust the capacitance of the second oscillation unit, while the capacitance of the first oscillation unit remains unchanged, that is, the capacitance of the first oscillation unit will not be used to compensate for the change of the frequency of the output signal of the voltage-controlled oscillation circuit with temperature, so it will not weaken the ability of the voltage-controlled oscillation circuit to cope with changes in the frequency and phase of the input clock or data.

[0059] like Figure 4 As shown, the feedback module 2 includes a comparison unit; the first input end of the comparison unit is used to obtain the reference voltage, the second input end is used to obtain the first control signal, and the output end is used to output the second control signal; the second control signal is used to control the capacitance value of the second oscillation unit according to the external input signal to output the target oscillation signal; the first control signal is used to feed back to the comparison unit when the target oscillation signal generates an offset to adjust the value of the second control signal and eliminate the offset. Optionally, the comparison unit is an operational amplifier or a comparator, and may also include other components according to actual conditions.

[0060] When the comparison unit is an operational amplifier Amp, the inverting input terminal of the operational amplifier Amp is used to input the reference voltage signal V ref , the non-inverting input terminal is used to input the first control signal V ctrl1 , the output terminal is used to output the second control signal V ctrl2 .

[0061] Figure 4 The voltage-controlled oscillator circuit in the embodiment introduces closed-loop feedback through an operational amplifier Amp with a bandwidth far lower than the phase-locked loop to achieve closed-loop automatic temperature compensation. The working principle of the circuit is as follows: the first transistor NM1, the second transistor NM2, the third transistor PM1 and the fourth transistor PM2 each form a negative resistance structure. Assume that the transconductance of the first transistor NM1 and the second transistor NM2 is G mn , the transconductance of the third transistor PM1 and the fourth transistor PM2 is G mp , the total negative resistance formed by the two negative resistances in parallel is R p is the equivalent parallel resistance when the LC network resonates. The oscillation module can maintain self-oscillation and output oscillation signal. Among them, C para is the parasitic capacitance introduced by transistors NM1, NM2, PM1, and PM2, C var1 , C var2 The first varicap diode Var1 and the second varicap diode Var2 corresponding to the first oscillation unit 11 and the second oscillation unit 12 respectively constitute a variable capacitor, and the third varicap diode Var3 and the fourth varicap diode Var4 constitute a variable capacitor. The capacitance value of the capacitor changes with the change of the voltage difference between the two ends. Assume that C var1 =K1*V ctrl1 +C C1 , C var2 =K2*V ctrl2 +C C2, K1, K2 are proportional constants, C C1 and C C2 is a fixed capacitor, C C1 +C C2 +C para =C C , the temperature coefficient of the total capacitance is K3, and the output of the voltage-controlled oscillator circuit is V OL and V OR , then the oscillation frequency of the oscillation module can be expressed as:

[0062]

[0063] The temperature compensation process of the voltage-controlled oscillator circuit of this embodiment is as follows:

[0064] Assume that the external input clock frequency is F in , during the power-on locking process of the voltage-controlled oscillator circuit, the first control signal V ctrl1 , the second control signal V ctrl2 Fixed at reference voltage V ref The phase-locked loop selects the appropriate capacitor array value, that is, F osc The n value in the formula is used to lock the input signal. After locking, the first control signal V ctrl1 and the second control signal V ctrl2 Will be at the reference voltage V ref The three can be considered equal, and the frequency F of the output signal of the voltage-controlled oscillation circuit is in The oscillation frequency F of the oscillation module osc Equal, that is:

[0065]

[0066] When the temperature changes, the frequency of the output signal of the voltage-controlled oscillator circuit also changes. Assume that the frequency of the output signal of the voltage-controlled oscillator circuit decreases by ΔF due to the increase of temperature by ΔT. In order to lock the output signal at F in , the phase-locked loop first sets the first control voltage V ctrl1 Voltage drop ΔV ctrl1 , the frequency of the output signal of the voltage-controlled oscillation circuit is increased by ΔF, and the phase-locked loop is relocked. At this time, the frequency of the output signal of the voltage-controlled oscillation circuit becomes:

[0067]

[0068] The first control signal V ctrl1 After the decrease, the operational amplifier Amp detects the change and keeps reducing the second control signal V ctrl2 , the second control signal V ctrl2The frequency of the output signal of the voltage-controlled oscillator circuit increases. In order to control the frequency of the output signal at Fin, the first control signal V ctrl1 The whole process is repeated until V ctrl1 =V ref , so far, the entire temperature compensation process is completed. At this time, the frequency of the output signal of the voltage-controlled oscillation circuit satisfies the following formula:

[0069]

[0070] After temperature compensation is completed, the first control signal V ctrl1 The voltage is still at the reference voltage V ref Nearby, the adjustable range of the variable capacitor of the first oscillation unit is not affected, so the capacitance of the first oscillation unit is not used to compensate for the change of the output signal frequency of the voltage-controlled oscillation circuit with temperature, so it will not weaken the ability of the voltage-controlled oscillation circuit to cope with changes in the input clock or data frequency and phase.

[0071] The function of the operational amplifier Amp in the voltage-controlled oscillation circuit of this embodiment is to introduce the change of the first control signal Vctrl1 into the feedback loop to realize automatic temperature compensation in a closed-loop form. Compared with a voltage-controlled oscillation circuit without temperature compensation, or a diode formed by short-circuiting the collector and base of a transistor, a temperature voltage is generated by a positive temperature voltage generating circuit to tune the varactor diode to realize temperature compensation, that is, compensation is performed through the temperature characteristics of the transistor, which is not actually feedback. In addition, the compensation capability of a single transistor is very limited, so the compensation accuracy is not high.

[0072] The voltage-controlled oscillation circuit of this embodiment uses the operational amplifier Amp to introduce the change of the first control signal Vctrl1 into the feedback loop to achieve closed-loop automatic temperature compensation, with more accurate compensation results and a wider compensation range. In other optional embodiments, the voltage-controlled oscillation circuit of this embodiment uses the operational amplifier Amp to introduce the change of the first control signal Vctrl1 into the feedback loop.

[0073] Figure 4 The feedback module 2 in also includes a capacitor C, one end of which is connected to the output end of the operational amplifier Amp, and the other end is grounded. The capacitor C is used to reduce the bandwidth of the operational amplifier on the one hand, and is used to filter the noise of the output signal of the operational amplifier Amp on the other hand, so as to improve the accuracy of the output signal. In other optional embodiments, such as the implementation case of the comparator, the capacitor C can be omitted.

[0074] Please see Figure 5 , a circuit diagram of an operational amplifier according to an embodiment of the present application.

[0075] The operational amplifier of this embodiment includes an NMOS transistor N1 , a transistor N2 , a transistor N3 , a transistor N4 , a transistor N5 , a transistor N6 , and PMOS transistors P1 , P2 , P3 , and P4 .

[0076] The sources of transistors N1 and N2 are connected to one end of current source S, the other end of current source S is connected to voltage VCC, the gate of transistor N1 is used as the inverting input terminal VIN of the operational amplifier, the gate of transistor N2 is used as the non-inverting input terminal VIP of the operational amplifier, the drain of transistor N1 is connected to the drain of N5, and the drain of transistor N2 is connected to the drain of N6; the substrates of transistors N3 and N4 are both connected to the ground, the source of N3 is connected to the drain of N5, the source of transistor N4 is connected to the drain of N6, the sources of transistors N5 and N6 are both connected to the ground GND, the drain of N3 is used as the output terminal VOUT of the operational amplifier, the drain of N3 is connected to the drain of transistor P3, the drain of transistor N4 is connected to the drain of P4 and the gates of transistors P1 and P2, the sources of transistors P1 and P2 are connected to the power supply VCC, the drain of transistor P1 is connected to the source of P3, and the drain of transistor P2 is connected to the source of P4. Wherein VCC represents the power supply voltage.

[0077] Figure 5 The circuit in is used to differentially amplify the signals inputted from the input terminals VIN and VIP to obtain the output signal VOUT of the operational amplifier.

[0078] Please see Figure 6 , a circuit diagram of an operational amplifier according to an embodiment of the present application.

[0079] The operational amplifier of this embodiment includes an NMOS transistor N51, a transistor N52, a transistor N53, a transistor N54, a transistor N55, a transistor N56, a transistor N57, and a transistor N58.

[0080] The sources of transistors N51 and N52 are connected to the voltage VCC, and the gates are connected to each other. The gate and drain of transistor N51 are connected, and the drain of transistor N51 is connected to the drain of N55. The drain of transistor N52 is connected to the drain of N58 and serves as the output terminal VOUT of the operational amplifier. The sources of transistors N53 and N54 are connected to one end of the current source S, the other end of the current source S is connected to the voltage VCC, and the gate of transistor N53 serves as the inverting input terminal VIN of the operational amplifier. The gate of transistor N54 serves as the non-inverting input terminal VIP of the operational amplifier, and the drain of transistor N53 is connected to the drain of N56. The drain of transistor N54 is connected to the drain of N57. The gate of transistor N56 is connected to its own drain and the gate of N55, and the gate of transistor N57 is connected to its own drain and the gate of N58. The sources of transistors N55, transistor N56, transistor N57 and N58 are all grounded GND.

[0081] Figure 6 The circuit in is used to differentially amplify the signals inputted from the input terminals VIN and VIP to obtain the output signal VOUT of the operational amplifier.

[0082] The voltage-controlled oscillator circuit of this embodiment retains Figure 2 Based on the two Varactor branches in Zhongyuan, the closed-loop feedback method is used to perform closed-loop automatic temperature compensation on the circuit to reduce the change of the output signal frequency of the voltage-controlled oscillation circuit with temperature. By adopting closed-loop feedback, the voltage-controlled oscillation circuit can automatically perform temperature compensation according to actual conditions, avoiding the degradation or loss of the phase-locked loop function due to insufficient or incorrect open-loop temperature compensation, thereby improving the performance of the phase-locked loop.

[0083] The embodiment of the present application also provides an electronic device including the voltage-controlled oscillator circuit, such as a mobile phone, a tablet computer, etc. The electronic device adopts the voltage-controlled oscillator circuit to achieve automatic temperature compensation and improve the performance of the phase-locked loop.

[0084] The above descriptions are merely embodiments of the present application and are not intended to limit the patent scope of the present application. Any equivalent structural or equivalent process transformations made using the contents of the specification and drawings of the present application, such as the mutual combination of technical features between the embodiments, or direct or indirect application in other related technical fields, are also included in the patent protection scope of the present application.

Claims

1. A voltage-controlled oscillator circuit, characterized in that: include: an oscillation module, responsive to a first control signal and a second control signal, for outputting a target oscillation signal according to the first control signal and the second control signal; a feedback module, responsive to the first control signal and the reference voltage signal, for adjusting the second control signal according to the first control signal and the reference voltage signal after the target oscillation signal is locked to keep the frequency of the target oscillation signal stable; The oscillation module comprises an impedance unit, a first oscillation unit and a second oscillation unit; the first end of the impedance unit is respectively connected to the first end of the first oscillation unit and the first end of the second oscillation unit, and serves as the first output end of the oscillation module; the second end of the impedance unit is respectively connected to the second end of the first oscillation unit and the second end of the second oscillation unit, and serves as the second output end of the oscillation module; the third end of the first oscillation unit responds to the first control signal, and the third end of the second oscillation unit responds to the second control signal to adjust the signal frequency output by the oscillation module; the first output end and the second output end are used to output the adjusted target oscillation signal; The first oscillation unit includes a first varactor diode and a second varactor diode; the cathode of the first varactor diode is connected to the cathode of the second varactor diode and is used to receive the first control signal, the anode of the first varactor diode is connected to the first output end of the oscillation module, and the anode of the second varactor diode is connected to the second output end of the oscillation module.

2. The voltage-controlled oscillator circuit according to claim 1, wherein: The feedback module includes a comparison unit; The first input terminal of the comparison unit is used to obtain the reference voltage, the second input terminal is used to obtain the first control signal, and the output terminal is used to output the second control signal; The first control signal is used to feed back to the comparison unit when the target oscillation signal generates an offset so as to adjust the value of the second control signal to eliminate the offset.

3. The voltage-controlled oscillator circuit according to claim 2, wherein: The comparison unit is an operational amplifier or a comparator.

4. The voltage-controlled oscillator circuit according to claim 1, wherein: The oscillation module also includes a negative resistance unit; The negative resistance unit is connected between the first oscillation unit and a power source, and is used to provide energy to the oscillation module.

5. The voltage-controlled oscillator circuit according to claim 4, characterized in that: The negative resistance unit includes a first transistor and a second transistor, the first end of the first transistor and the first end of the second transistor are connected to a voltage source, the second end of the first transistor and the third end of the second transistor are connected to the second output end of the oscillation module, and the third end of the first transistor and the second end of the second transistor are connected to the first output end of the oscillation module.

6. The voltage-controlled oscillator circuit according to claim 5, characterized in that: The negative resistance unit further includes a third transistor and a fourth transistor, The first end of the third transistor and the first end of the fourth transistor are connected to the ground, the second end of the third transistor and the third end of the fourth transistor are connected to the second output end of the oscillation module, and the third end of the third transistor and the second end of the fourth transistor are connected to the first output end of the oscillation module.

7. The voltage-controlled oscillator circuit according to claim 3, characterized in that: When the comparison unit is an operational amplifier, the inverting input terminal of the operational amplifier is used to input the reference voltage signal, the non-inverting input terminal is used to input the first control signal, and the output terminal is used to output the second control signal; The value of the first control signal at power-on locking is equal to the value after the offset is eliminated.

8. The voltage-controlled oscillator circuit according to claim 7, characterized in that: Also included are capacitors; One end of the capacitor is connected to the output end of the operational amplifier, and the other end of the capacitor is grounded.

9. The voltage-controlled oscillator circuit according to claim 7 or 8, characterized in that: The oscillation module further comprises a capacitor array, one end of the capacitor array is connected to the first output end, and the other end of the capacitor array is connected to the second output end; The impedance unit is an inductor, one end of the inductor is connected to the first output end, and the other end of the inductor is connected to the second output end; After eliminating the offset, the frequency F of the target oscillation signal in Satisfies the following formula: Wherein, Fin is the frequency of the target oscillation signal, L ind is the inductance of the inductor, K1 and K2 are proportional constants, K3 is the temperature coefficient, T is the temperature, ΔT is the temperature change, V ref is the reference voltage, V ctrl2 is the second control signal, ΔV ctrl2 is the second control signal offset, n*C band is the capacitance of the capacitor array, C C is the total capacitance of the first oscillation unit and the second oscillation unit.

10. An electronic device, characterized in that: A voltage-controlled oscillator circuit comprising any one of claims 1 to 9.

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