Switched capacitor circuit, circuit configuration method and device and voltage-controlled oscillator

Abstract

The invention relates to the technical field of circuits, and discloses a switched capacitor circuit, a circuit configuration method and device and a voltage-controlled oscillator, and the circuit comprises a switched capacitor module and a cross coupling module. The switched capacitor module comprises a first capacitor, a control switch tube, a second capacitor, a first switch tube and a second switch tube; the first end of the control switch tube is used for receiving a first control signal; the second end of the control switch tube is connected to the first output end through the first capacitor; the second end of the control switch tube is also grounded through the first switch tube; the third end of the control switch tube is connected to the second output end through the second capacitor; the third end of the control switch tube is also grounded through the second switch tube; and the cross coupling module is used for controlling the working state of the cross coupling module according to the second control signal so as to neutralize the parasitic capacitance between the second end of the control switch tube and the third end of the control switch tube. According to the invention, stray capacitance can be eliminated so as to widen the frequency modulation range of the VCO.

Description

Technical Field

[0001] The present invention relates to the field of circuit technology, and in particular to a switched capacitor circuit, a circuit configuration method, a device and a voltage-controlled oscillator. Background Art

[0002] VCO (Voltage Controlled Oscillator) is the control object of the phase-locked loop, and together with the phase-locked loop, it constitutes a frequency synthesizer. The VCO circuit requires a wide adjustment range.

[0003] The phase-locked loop includes a phase detector, a loop filter, a frequency divider, and a voltage-controlled oscillator. The phase-locked loop inputs a stable reference clock signal with a frequency of f ref , the reference clock signal is input into the phase detector, and the voltage-controlled oscillator generates a frequency f vco The output signal of vco f ref The signal is divided by 1 / N to obtain a frequency of f vco / N feedback signal; the phase detector detects the phase difference between the reference clock signal and the feedback signal to output an error signal proportional to the phase difference; the loop filter generates a control voltage after filtering the error signal output by the phase detector; the voltage-controlled oscillator adjusts the output frequency according to the control voltage, so that the frequency and phase of the feedback signal gradually approach those of the reference clock signal to achieve phase lock. In related technologies, discrete frequency modulation is usually used to widen the frequency modulation range. However, parasitic capacitance will be introduced, which will reduce the performance indicators of the VCO frequency modulation range.

[0004] In view of this, a switched capacitor circuit capable of eliminating parasitic capacitance is needed. Summary of the invention

[0005] In view of this, the present invention provides a switched capacitor circuit capable of eliminating parasitic capacitance.

[0006] In the first aspect, the present invention provides a switching capacitor circuit, which includes a switching capacitor module and a cross-coupling module; the switching capacitor module includes a first capacitor, a control switch tube, a second capacitor, a first switch tube and a second switch tube; the first end of the control switch tube is used to receive a first control signal; the second end of the control switch tube is connected to the first output end through the first capacitor; the second end of the control switch tube is also grounded through the first switch tube; the third end of the control switch tube is connected to the second output end through the second capacitor; the third end of the control switch tube is also grounded through the second switch tube; the control ends of the first switch tube and the second switch tube are used to receive control signals; the cross-coupling module is used to control the working state of the cross-coupling module according to the second control signal to neutralize the negative capacitance between the second end of the control switch tube and the third end of the control switch tube.

[0007] In this embodiment, by receiving a control signal and controlling the closing and opening of the control switch tube, the first switch tube and the second switch tube according to the control signal, the capacitance of the first output terminal and the second output terminal to ground is adjusted. The working state of the cross-coupling module is controlled by the second control signal to neutralize the negative capacitance between the second end of the control switch tube and the third end of the control switch tube. The performance of the circuit can be optimized according to the working conditions of the circuit, and the flexibility and adaptability of the circuit can be improved.

[0008] In an optional implementation, the control switch tube is used to receive a first control signal and control the capacitance to ground of the first output terminal and the second output terminal according to the first control signal.

[0009] In this embodiment, the control switch tube receives the first control signal and adjusts the capacitance to ground of the first output terminal and the second output terminal of the switch capacitor circuit according to the first control signal, which can improve the flexibility of frequency adjustment and thus improve the adaptability of the voltage controlled oscillator.

[0010] In an optional implementation, the first switch tube is an n-type metal oxide semiconductor transistor.

[0011] In this embodiment, the first switch tube is an n-type metal oxide semiconductor transistor, which can reduce the requirements for the driving circuit and simplify the design and layout of the circuit.

[0012] In an optional implementation, the second switch tube is an n-type metal oxide semiconductor transistor.

[0013] In this embodiment, the second switch tube is an n-type metal oxide semiconductor transistor, which can reduce the requirements for the driving circuit and simplify the design and layout of the circuit.

[0014] In an optional embodiment, the cross-coupling module includes a first transistor, a second transistor and a third capacitor; the first transistor is cross-coupled to the second transistor; the first end of the third capacitor is connected to the source of the first transistor, and the second end of the third capacitor is connected to the source of the second transistor; the first transistor and the second transistor are n-type metal oxide semiconductor transistors.

[0015] In this embodiment, the first transistor is cross-coupled to the second transistor, which can provide a negative resistance effect in the circuit. The first end of the third capacitor is connected to the source of the first transistor, and the second end of the third capacitor is connected to the source of the second transistor, which can provide a negative capacitance effect for the circuit, thereby neutralizing the negative capacitance between the second and third ends of the control switch tube.

[0016] In an optional implementation, the cross-coupling module further includes a third switch tube, wherein: the third switch tube is used to control the enabling of the cross-coupling module.

[0017] In this embodiment, the third switch tube can control the enabling of the cross-coupling module, thereby controlling whether the cross-coupling module neutralizes the parasitic capacitance between the second end of the control switch tube and the third end of the control switch tube, thereby improving the flexibility of the circuit.

[0018] In an optional embodiment, the cross-coupling module also includes a first resistor and a second resistor; the first resistor connects the drain of the first transistor, the gate of the second transistor and the third switch tube; the second resistor connects the drain of the second transistor, the gate of the first transistor and the third switch tube.

[0019] In this embodiment, the first resistor and the second resistor can provide bias voltages for the first transistor and the second transistor to ensure that the first transistor and the second transistor can work normally.

[0020] In a second aspect, the present invention provides a voltage-controlled oscillator, which includes the switched capacitor circuit of the first aspect or any corresponding embodiment thereof.

[0021] In a third aspect, the present invention provides a circuit configuration method for a switched capacitor circuit, which is applied to a voltage-controlled oscillator. The voltage-controlled oscillator includes a switched capacitor circuit, and the circuit includes a switched capacitor module and a cross-coupling module; the switched capacitor module includes a first capacitor, a control switch tube, a second capacitor, a first switch tube and a second switch tube; the first end of the control switch tube is used to receive a first control signal; the second end of the control switch tube is connected to the first output end through the first capacitor; the second end of the control switch tube is also grounded through the first switch tube; the third end of the control switch tube is connected to the second output end through the second capacitor; the third end of the control switch tube is also grounded through the second switch tube; the first switch tube and The control end of the second switch tube is used to receive a control signal; the cross-coupling module is used to control the working state of the cross-coupling module according to the second control signal to neutralize the parasitic capacitance between the second end of the control switch tube and the third end of the control switch tube; the cross-coupling module also includes a third switch tube, and the third switch tube is used to control the enabling of the cross-coupling module; the method includes: obtaining the working state of the third switch tube; when the working state of the third switch tube is enabled, the cross-coupling module stops working; when the working state of the third switch tube is disabled, the cross-coupling module works normally to neutralize the negative capacitance between the second end of the control switch tube and the third end of the control switch tube.

[0022] In a fourth aspect, the present invention provides a circuit configuration device for a switching capacitor circuit, the device comprising: an acquisition module for acquiring the working state of a third switching tube; an enabling module for stopping the cross-coupling module from working when the working state of the third switching tube is enabled; and a disabling module for enabling the cross-coupling module to work normally when the working state of the control switch is disabled, so as to neutralize the negative capacitance between the second end of the control switch tube and the third end of the control switch tube. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0024] Figure 1 It is a simplified functional block diagram of a phase-locked loop;

[0025] Figure 2 It is a graph of the relationship between the control voltage and the output frequency in a voltage-controlled oscillator;

[0026] Figure 3 It is a circuit diagram of discrete frequency modulation of a voltage-controlled oscillator;

[0027] Figure 4 It is a graph of the relationship between the control voltage and output frequency of a voltage-controlled oscillator in discrete frequency modulation;

[0028] Figure 5 It is a circuit diagram of a conventional switched capacitor;

[0029] Figure 6 It is a comparison chart of the relationship between the control voltage and output frequency of a voltage-controlled oscillator in discrete frequency modulation under ideal conditions and using conventional switched capacitors;

[0030] Figure 7 is a circuit diagram of a switched capacitor according to an embodiment of the present invention;

[0031] Figure 8 is a schematic flow chart of a circuit configuration method of a switched capacitor circuit according to an embodiment of the present invention;

[0032] Fig. 9 is a structural block diagram of a circuit configuration device of a switched capacitor circuit according to an embodiment of the present invention;

[0033] Fig.10 It is a schematic diagram of the hardware structure of a computer device according to an embodiment of the present invention. DETAILED DESCRIPTION

[0034] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.

[0035] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0036] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, it can also be the internal connection of two components, it can be a wireless connection, or it can be a wired connection. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0037] In addition, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0038] The phase-locked loop includes a phase detector, a loop filter, a frequency divider, and a voltage-controlled oscillator. The simplified functional block diagram of the phase-locked loop is shown in Figure 1 As shown, a stable reference clock signal is input, and the frequency of the reference clock signal is f ref , the reference clock signal is input into the phase detector, and the voltage-controlled oscillator generates a frequency f vco The output signal of vco f ref The signal is divided by 1 / N to obtain a frequency of f vco / N feedback signal; the phase detector detects the phase difference between the reference clock signal and the feedback signal to output an error signal proportional to the phase difference; the loop filter filters the error signal output by the phase detector and generates a control voltage; the voltage-controlled oscillator adjusts the output frequency according to the control voltage, so that the frequency and phase of the feedback signal gradually approach those of the reference clock signal, thereby achieving phase locking.

[0039] The relationship between the control voltage and the output frequency in a voltage-controlled oscillator is as follows: Figure 2 As shown, where V cont is the control voltage, ω out is the output frequency. When the control voltage changes from V1 to V2, the output frequency changes from ω1 to ω2. The slope of the curve K vco is called the gain of the oscillator, where the expression of the output frequency is as follows:

[0040] ω out =K vco V cont +ω0

[0041] Among them, ω out is the output frequency, K vco is the gain of the oscillator, V cont is the control voltage, ω0 is the minimum output frequency of the oscillator.

[0042] In the related art, the resonant frequency is adjusted by connecting the switch capacitor and the resonant cavity in parallel to widen the frequency modulation range, such as Figure 3 As shown, several capacitors and switches are connected in parallel to form several switch capacitor branches. Several switch capacitor branches are connected in parallel with inductors, adjustable capacitors and cross-coupling tubes. Current flows into the connection part of the two inductors. V cont is the control voltage. n capacitors are connected in parallel with the resonant cavity through switches. By changing the switch state, the capacitance value in the circuit is adjusted, thereby adjusting the resonant frequency. V cont The relationship between the control voltage, control voltage and output frequency is shown in the figure below: Figure 4 As shown, "0×C u " indicates the relationship between the control voltage and the output frequency when all switches in the circuit are disconnected; "C u " represents the relationship between the control voltage and the output frequency when switch 1 in the circuit is closed and the other switches are open; "(n-1)C u " indicates the relationship between the control voltage and the output frequency when switches 1 to n-1 in the circuit are closed and the other switches are open; "nC u "Indicates the relationship between the control voltage and the output frequency when all switches in the circuit are closed. out is the output frequency, V cont is the control voltage, V1 and V2 are both control voltages, ω min is the minimum output frequency, ω max is the maximum output frequency.

[0043] Among them, the circuit diagram of the switched capacitor is as follows Figure 5 As shown, it includes two capacitors and three switch tubes, the capacitance of the two capacitors is the same, the three switch tubes are all n-type metal oxide semiconductor transistors, and the three switch tubes SW1, SW2 and SW3 can be controlled by the same control signal, and closed or disconnected at the same time. SW1 is connected in series between the two capacitors. By controlling the high and low gate level signal of SW1, the circuit connection between the two capacitors can be turned on and off, thereby changing the capacitance between outp and outm. Among them, when SW1 is closed, capacitor C1 and capacitor C2 are connected, the capacitance to ground of outp and outm is the largest, and the capacitance to ground of outp and outm is the capacitance value of capacitors C1 and C2. When SW1 is disconnected, capacitor C1 and capacitor C2 are disconnected, and the capacitance to ground of outp and outm is the smallest, both of which are twice the parasitic capacitance Cpar in SW1. When SW1 is disconnected, the presence of parasitic capacitance will make it impossible to achieve the capacitance value of 0 in the ideal state, resulting in a reduction in the range of circuit frequency adjustment and a reduction in the frequency modulation range of the VCO.

[0044] like Figure 6 As shown, where ωout is the output frequency, V cont is the control voltage, V1 and V2 are both control voltages, ω min is the minimum output frequency, ω max The left figure shows the relationship between the control voltage and output frequency of the voltage-controlled oscillator in discrete frequency modulation under ideal conditions. u " indicates the relationship between the control voltage and the output frequency when all switches in the circuit are disconnected; "C u " represents the relationship between the control voltage and the output frequency when switch 1 in the circuit is closed and the other switches are open; "(n-1)C u " indicates the relationship between the control voltage and the output frequency when switches 1 to n-1 in the circuit are closed and the other switches are open; "nC u ” indicates the relationship between the control voltage and the output frequency when all switches in the circuit are closed. The figure on the right shows the relationship between the control voltage and the output frequency of the voltage-controlled oscillator in discrete frequency modulation using conventional switched capacitors. Among them, “n×2Cpar’’ indicates the relationship between the control voltage and the output frequency when all switches in the circuit are disconnected; “Cu+(n-1)×2Cpar’’ indicates the relationship between the control voltage and the output frequency when switch 1 in the circuit is closed and the other switches are disconnected; “(n-1)Cu+2Cpar” indicates the relationship between the control voltage and the output frequency when switches 1 to n-1 in the circuit are closed and the other switches are disconnected; “nC u " indicates the relationship between the control voltage and the output frequency when all switches in the circuit are closed. Compared with the ideal state, the circuit frequency adjustment range is reduced by Δω.

[0045] The embodiment of the present invention provides a switched capacitor circuit, which receives a control signal and controls the closing and opening of a control switch tube, a first switch tube, and a second switch tube according to the control signal, thereby adjusting the capacitance of the first output terminal and the second output terminal to ground. The working state of the cross-coupling module is controlled by a second control signal to neutralize the negative capacitance between the second end of the control switch tube and the third end of the control switch tube. The performance of the circuit can be optimized according to the working conditions of the circuit, and the flexibility and adaptability of the circuit can be improved.

[0046] According to an embodiment of the present invention, a switched capacitor circuit is provided, such as Figure 7 As shown, the circuit includes a switched capacitor module and a cross-coupling module;

[0047] The switch capacitor module includes a first capacitor 101, a control switch tube 102, a second capacitor 103, a first switch tube 104 and a second switch tube 105; the first end of the control switch tube 102 is used to receive a first control signal; the second end of the control switch tube 102 is connected to the first output end 106 through the first capacitor 101; the second end of the control switch tube 102 is also grounded through the first switch tube 104.

[0048] The third end of the control switch tube 102 is connected to the second output end 107 through the second capacitor 103; the third end of the control switch tube 102 is also grounded through the second switch tube 105; the control ends of the first switch tube 104 and the second switch tube 105 are used to receive control signals.

[0049] Among them, the capacitance values ​​of the first capacitor 101 and the second capacitor 103 can be set according to the working conditions of the switch capacitor circuit. The first capacitor 101 and the second capacitor 103 are connected through the control switch tube 102. When the control switch tube 102 is turned on and the first switch tube 104 and the second switch tube 105 are both turned off, the first capacitor 101 and the second capacitor 103 are connected in series, and the capacitance to ground of the first output end 106 and the second output end 107 is the equivalent capacitance of the first capacitor 101 and the second capacitor 103 in series; when the control switch tube 102 and the first switch tube 104 are turned on and the second switch tube 105 is turned off, the capacitance to ground of the first output end 106 and the capacitance value of the first capacitor 101, and the capacitance to ground of the second output end 107 is the capacitance value of the second capacitor 103; when the control switch tube 102 and the second switch tube 105 are turned on and the first switch tube 104 is turned off, the capacitance to ground of the first output end 106 is the capacitance value of the first capacitor 101, and the capacitance to ground of the second output end 107 is the capacitance value of the second capacitor 103.

[0050] The first switch tube 104 connects the second end of the control switch tube 102 and the ground, and can play a filtering role. When there is a high-frequency signal or an interference signal in the circuit, the grounding path of the first switch tube 104 can guide the unnecessary signal components or interference signals to the ground, so as to improve the stability of the circuit.

[0051] The second switch tube 105 is connected to the third terminal of the control switch tube 102 and the ground, and can also play a filtering role. Interference signals can be guided to the ground through the ground path to improve the stability of the circuit.

[0052] In some optional implementations, the control switch tube 102 is used to receive a first control signal and control the capacitance to ground of the first output terminal 106 and the second output terminal 107 according to the first control signal.

[0053] Among them, the first end of the control switch tube 102 is used to receive the first control signal, and the control switch tube 102 can be controlled to be turned on according to the first control signal. The first control signal can be generated by an external circuit or a controller. In the case where the control switch tube 102 is a field effect transistor switch tube, when the first control signal can make the gate voltage of the control switch tube 102 reach a certain threshold, the control switch tube 102 is turned on. When the first control signal does not meet the turn-on condition of the control switch tube 102, the control switch tube 102 is turned off. By controlling whether the switch tube 102 is turned on, the capacitance to ground of the first output terminal 106 and the second output terminal 107 can be controlled.

[0054] The first control signal may be generated by a microcontroller or a microprocessor, or by a staff member operating a touch screen, a toggle switch, etc. to generate the first control signal to control the on and off of the control switch tube 102 .

[0055] In an actual application, the control switch tube 102 is an n-type metal oxide semiconductor transistor, the gate of the control switch tube 102 receives the first control signal, the drain of the control switch tube 102 is connected to the second capacitor 103, and the source of the control switch tube 102 is connected to the first capacitor 101.

[0056] Controlling the switch tube 102 to receive the first control signal and adjusting the capacitance to ground of the first output terminal 106 and the second output terminal 107 of the switch capacitor circuit according to the first control signal can improve the flexibility of frequency adjustment, thereby improving the adaptability of the voltage controlled oscillator.

[0057] In some optional implementations, the control switch tube 102 , the first switch tube 104 , and the second switch tube 105 may be controlled by the first control signal at the same time.

[0058] Wherein, when the control switch tube 102, the first switch tube 104, and the second switch tube 105 are all switches of the same type, the control switch tube 102, the first switch tube 104, and the second switch tube 105 can be controlled by a control signal to simplify the layout of the circuit. In an actual application, the control switch tube 102, the first switch tube 104, and the second switch tube 105 are all n-type metal oxide semiconductor transistors, and their gates can be connected and receive a first control signal. When the first control signal can provide a higher threshold voltage than the three switch tubes, the three switch tubes are turned on, and when the first control signal cannot provide a higher threshold voltage than the three switch tubes, the three switch tubes are all in a disconnected state.

[0059] In some optional implementations, the first switch tube 104 is an n-type metal oxide semiconductor transistor.

[0060] The gate of the first switch tube 104 is connected to the control signal, the source of the first switch tube 104 is connected to the ground, and the drain of the first switch tube 104 is connected to the second end of the control switch tube 102 .

[0061] The first switch tube 104 is an n-type metal oxide semiconductor transistor, which can reduce the requirements for the driving circuit and simplify the design and layout of the circuit.

[0062] In some optional implementations, the second switch tube 105 is an n-type metal oxide semiconductor transistor.

[0063] The gate of the second switch tube 105 is connected to the control signal, the source of the second switch tube 105 is connected to the ground, and the drain of the second switch tube 105 is connected to the third end of the control switch tube 102 .

[0064] The second switch tube 105 is an n-type metal oxide semiconductor transistor, which can reduce the requirements for the driving circuit and simplify the design and layout of the circuit.

[0065] The cross-coupling module is used to control the working state of the cross-coupling module according to the second control signal to neutralize the parasitic capacitance between the second end of the control switch tube 102 and the third end of the control switch tube 102 .

[0066] Among them, a negative resistance converter and a capacitor can be directly connected in series to be equivalent to a negative capacitor element, and the equivalent circuit can be connected in parallel with the second end of the control switch tube and the third end of the control switch tube to neutralize the parasitic capacitance between the second end of the control switch tube and the third end of the control switch tube.

[0067] It can also be formed by cross-coupling transistors, using two CMOS (Complementary Metal Oxide Semiconductor) inverters for cross-coupling, each inverter includes a PMOS (P-channel Metal-Oxide-Semiconductor, P-channel Metal-Oxide-Semiconductor) tube and an NMOS (N-channel Metal-Oxide-Semiconductor, N-channel Metal-Oxide-Semiconductor) tube, and when the output ends of the two inverters are connected to each other's input ends, a positive feedback circuit is formed. When current flows into this circuit, due to the positive feedback effect, the voltage at both ends of the circuit increases, which can make the relationship between current and voltage present the characteristics of negative resistance, so it can be regarded as a negative resistance. Using a capacitor and a cross-coupling transistor in series, the series circuit can present the characteristics of negative capacitance. The input ends of the two inverters are respectively connected to the second end and the third end of the control switch tube 102 in the switch capacitor module, and the parasitic capacitance between the second end of the control switch tube 102 and the third end of the control switch tube 102 can be neutralized.

[0068] In some optional embodiments, the cross-coupling module includes a first transistor 201, a second transistor 202 and a third capacitor 203; the first transistor 201 is cross-coupled to the second transistor 202; the first end of the third capacitor 203 is connected to the source of the first transistor 201, and the second end of the third capacitor 203 is connected to the source of the second transistor 202; the first transistor 201 and the second transistor 202 are n-type metal oxide semiconductor transistors.

[0069] The first transistor 201 and the second transistor 202 may be the same transistor to obtain a stable negative resistance effect. If the parameters of the two transistors are greatly different, the symmetry of the circuit will be destroyed, affecting the generation and stability of the negative resistance.

[0070] The first transistor 201 is cross-coupled to the second transistor 202, which can provide a negative resistance effect in the circuit. The first end of the third capacitor 203 is connected to the source of the first transistor 201, and the second end of the third capacitor 203 is connected to the source of the second transistor 202, which can provide a negative capacitance effect for the circuit, thereby neutralizing the negative capacitance between the second end and the third end of the switch capacitor module.

[0071] When the cross-coupling module works normally, the minimum grounding capacitance of the first output terminal 106 and the second output terminal 107 can be obtained through actual simulation results.

[0072] In some optional implementations, the cross-coupling module further includes a third switch tube 204, wherein: the third switch tube 204 is used to control the enabling of the cross-coupling module.

[0073] The third switch tube 204 may be a p-type metal oxide semiconductor transistor, the source of the third switch tube 204 is connected to the power supply, and the drain of the third switch tube 204 is connected to the drain of the first transistor 201 and the drain of the second transistor 202. A control signal may be sent to the gate of the p-type metal oxide semiconductor transistor to adjust the negative voltage between the gate and the source of the p-type metal oxide semiconductor transistor, and the third switch tube 204 is turned on when the negative voltage is lower than the threshold voltage, and the third switch tube 204 is closed when the negative voltage is higher than the threshold voltage.

[0074] In some optional implementations, the first control signal can control the switch tube 102 , the first switch tube 104 , the second switch tube 105 and the third switch tube 204 .

[0075] The peripheral circuits of the four switch tubes can be designed and laid out according to the types of the control switch tube 102, the first switch tube 104, the second switch tube 105 and the third switch tube 204. The first control signal is connected to the first end of the control switch tube 102, and the first control signal is connected to the control ends of the first switch tube 104, the second switch tube 105 and the third switch tube 204.

[0076] In a practical application, the control switch tube 102, the first switch tube 104, and the second switch tube 105 are all n-type metal oxide semiconductor transistors, and the third switch tube 204 is a p-type metal oxide semiconductor transistor. The peripheral circuit of the switch tube can be designed according to the conduction conditions of the n-type metal oxide semiconductor transistor and the p-type metal oxide semiconductor transistor. Then, the conduction of the four switch tubes is controlled by the first control signal. When the source of the p-type metal oxide semiconductor transistor is connected to the power supply, the first control signal is connected to the gate of the four switch tubes, and the gate-source voltage of the control switch tube 102, the first switch tube 104, and the second switch tube 105 is adjusted by changing the voltage of the first control signal, so that the gate-source voltage of the switch tube is greater than the threshold voltage of the corresponding switch tube; the gate-source voltage of the third switch tube 204 is adjusted so that its gate-source voltage is less than the threshold voltage of the corresponding third switch tube and is negative, so that the four switch tubes can be turned on or off at the same time. Among them, the threshold voltage can be determined according to the parameters of the control switch tube, the first switch tube, the second switch tube, and the third switch tube.

[0077] The third switch tube 204 can control the enabling of the cross-coupling module, thereby controlling whether the cross-coupling module neutralizes the parasitic capacitance between the second end of the control switch tube 102 and the third end of the control switch tube 102. The flexibility of the circuit can be improved.

[0078] In some optional embodiments, the cross-coupling module also includes a first resistor 205 and a second resistor 206, the first resistor 205 is connected to the drain of the first transistor 201, the gate of the second transistor 202 and the third switch tube 204; the second resistor 206 is connected to the drain of the second transistor 202, the gate of the first transistor 201 and the third switch tube 204.

[0079] The sizes of the first resistor 205 and the second resistor 206 can be determined according to the operating voltages of the first transistor 201 and the second transistor 202. In a practical application, the third switch tube 204 is connected to VDD (Voltage Device Driver) to obtain the operating voltages of the first transistor 201 and the second transistor 202, and then the size and the operating voltage of the VDD connected to the third switch tube 204 are determined, the resistance values ​​of the first resistor 205 and the second resistor 206 are determined, the static operating points of the two transistors are set, and the gate is provided with a suitable bias voltage, so that the first transistor 201 and the second transistor 202 can be in a suitable working state by means of voltage division.

[0080] In some optional implementations, the source of the first transistor 201 is connected to the ground via the first current source 207 , and the source of the second transistor 202 is connected to the ground via the second current source 208 .

[0081] The current in the amplifier circuit is provided by a first current source 207 and a second current source 208 .

[0082] In some optional implementations, the source of the first transistor 201 and the source of the second transistor 202 are connected to ground through the same current source.

[0083] The first resistor 205 and the second resistor 206 can provide bias voltages for the first transistor 201 and the second transistor 202 to ensure that the first transistor 201 and the second transistor 202 can work normally.

[0084] In a practical application, the capacitance values ​​of the first capacitor 101 and the second capacitor 103 are both 39.2fF. When the parasitic capacitance Cpar between the second end and the third end of the control switch tube 102 is 4.3fF, the maximum grounding capacitance Cmax of the first output end 106 and the second output end 107 is 39.2fF, and the minimum grounding capacitance Cmin of the first output end 106 and the second output end 107 is 8.6fF, then (Cmax-Cmin) / Cmax=78%; when the cross-coupling module is connected to the switch capacitor module, the third capacitor 203 and the cross-coupled first transistor 201 and the second transistor 202 work together. When the third capacitor 203 is 9fF, the minimum grounding capacitance of the first output end 106 and the second output end 107 becomes 0.2fF, (Cmax-Cmin) / Cmax=99.5%, which means that the frequency modulation range is significantly improved.

[0085] In another practical application, the capacitance values ​​of the first capacitor 101 and the second capacitor 103 are both 60fF, and when the parasitic capacitance Cpar between the second end and the third end of the control switch tube 102 is 7fF, the maximum grounding capacitance Cmax of the first output end 106 and the second output end 107 is 60fF, and the minimum grounding capacitance Cmin of the first output end 106 and the second output end 107 is 14fF, then (Cmax-Cmin) / Cmax=76.7%; when the cross-coupling module is connected to the switch capacitor module, the third capacitor 203 and the cross-coupled first transistor 201 and the second transistor 202 work together, and when the third capacitor 203 is 15fF, the minimum grounding capacitance of the first output end 106 and the second output end 107 becomes 0.4fF, (Cmax-Cmin) / Cmax=99.3%, which means that the frequency modulation range is significantly improved.

[0086] In another practical application, the capacitance values ​​of the first capacitor 101 and the second capacitor 103 are both 70fF, and when the parasitic capacitance Cpar between the second end and the third end of the control switch tube 102 is 8fF, the maximum grounding capacitance Cmax of the first output end 106 and the second output end 107 is 70fF, and the minimum grounding capacitance Cmin of the first output end 106 and the second output end 107 is 16fF, then (Cmax-Cmin) / Cmax=77.1%; when the cross-coupling module is connected to the switch capacitor module, the third capacitor 203 and the cross-coupled first transistor 201 and the second transistor 202 work together, and when the third capacitor 203 is 18fF, the minimum grounding capacitance of the first output end 106 and the second output end 107 becomes 0.45fF, (Cmax-Cmin) / Cmax=99.36%, which means that the frequency modulation range is significantly improved.

[0087] By receiving the control signal and controlling the closing and opening of the control switch tube 102, the first switch tube 104 and the second switch tube 105 according to the control signal, the capacitance to ground of the first output terminal 106 and the second output terminal 107 is adjusted. The working state of the cross-coupling module is controlled by the second control signal to neutralize the negative capacitance between the second end of the control switch tube 102 and the third end of the control switch tube 102. The performance of the circuit can be optimized according to the working conditions of the circuit, and the flexibility and adaptability of the circuit can be improved.

[0088] In a practical application, the control switch tube 102 is an n-type metal oxide semiconductor transistor, and the larger the size, the larger the parasitic capacitance between the second end and the third end of the control switch tube 102. After the parasitic capacitance is neutralized by the cross-coupling module, the size of the control switch tube 102 can be appropriately increased, thereby reducing the series resistance when the switch capacitor is closed, so as to improve the Q value when closed.

[0089] In this embodiment, a voltage-controlled oscillator is provided. The voltage-controlled oscillator includes the switched capacitor circuit in the above-mentioned embodiment and preferred implementation manner.

[0090] By using the switched capacitor circuit in the above-mentioned embodiments and preferred implementations in a voltage-controlled oscillator, the frequency modulation range of the voltage-controlled oscillator can be widened at a smaller cost of area and power consumption, and the additional margin of the frequency modulation range of the voltage-controlled oscillator can be increased, wherein the additional margin includes process deviations, temperature changes, model errors, etc.

[0091] In the present embodiment, a circuit configuration method of a switched capacitor circuit is provided, and the method is applied to a voltage-controlled oscillator, wherein the voltage-controlled oscillator includes a switched capacitor circuit, and the circuit includes a switched capacitor module and a cross-coupling module; the switched capacitor module includes a first capacitor, a control switch tube, a second capacitor, a first switch tube, and a second switch tube; the first end of the control switch tube is used to receive a first control signal; the second end of the control switch tube is connected to the first output end through the first capacitor; the second end of the control switch tube is also grounded through the first switch tube; the third end of the control switch tube is connected to the second output end through the second capacitor; the third end of the control switch tube is also grounded through the second switch tube; the control ends of the first switch tube and the second switch tube are used to receive a control signal; the cross-coupling module is used to control the working state of the cross-coupling module according to the second control signal to neutralize the parasitic capacitance between the second end of the control switch tube and the third end of the control switch tube; the cross-coupling module also includes a third switch tube, and the third switch tube is used to control the enabling of the cross-coupling module; Figure 8 is a flow chart of a circuit configuration method of a switched capacitor circuit according to an embodiment of the present invention. Figure 8 As shown, the process includes the following steps:

[0092] Step S301, obtaining the working state of the third switch tube.

[0093] Among them, it is necessary to first determine the conduction condition of the third switch tube. In an actual application, the third switch tube is a p-type metal oxide semiconductor transistor, and the gate and source voltages of the third switch tube are measured by a measuring instrument. When the voltage difference between the gate voltage and the source voltage is greater than the conduction voltage of the third switch tube, it is determined that the third switch tube is enabled, and when the voltage difference between the gate voltage and the source voltage is less than the conduction voltage of the third switch tube, the third switch tube is closed.

[0094] In the case where the third switch tube is controlled by a control signal, the working state of the third switch tube can also be obtained according to the control signal.

[0095] Step S302: when the working state of the third switch tube is enabled, the cross-coupling module stops working.

[0096] When the working state of the third switch tube is enabled, the cross-coupling circuit stops working. When the control switch tube is disconnected, the cross-coupling circuit has no effect on the parasitic capacitance at both ends of the control switch tube.

[0097] Step S303: when the working state of the third switch tube is disabled, the cross-coupling module works normally to neutralize the negative capacitance between the second end of the control switch tube and the third end of the control switch tube.

[0098] Wherein, when the working state of the third switch tube is disabled, the cross-coupling module works normally.

[0099] In some optional embodiments, the cross-coupling module includes a first transistor, a second transistor and a third capacitor. In the case of current flowing into the cross-coupling module, the first transistor and the second transistor constitute a positive feedback structure. When current flows through one of the transistors, its voltage change affects the other transistor through positive feedback, causing the direction of change of the current in the two transistors to be opposite to that of the normal positive resistance, constituting the effect of a negative resistance. The third capacitor is connected to the source of the first transistor and the second transistor. When the voltage in the path increases, the voltage at both ends of the negative resistance is negative, so that the actual charging voltage at both ends of the third capacitor is reduced, so the third capacitor and the cross-coupled first transistor and the second transistor can be equivalent to a component with negative capacitance characteristics. The drain of the first transistor and the drain of the second transistor in the cross-coupling module are respectively connected to the second end and the third end of the control switch tube in the switch capacitor module, and the negative capacitance between the second end of the control switch tube and the third end of the control switch tube can be neutralized.

[0100] The circuit configuration method of the switched capacitor circuit provided in this embodiment determines whether to neutralize the negative capacitance between the second end of the control switch tube and the third end of the control switch tube according to the working state of the third switch tube, which can improve the flexibility of the circuit.

[0101] In this embodiment, a circuit configuration device for a switched capacitor circuit is also provided, which is used to implement the above-mentioned embodiments and preferred implementation modes, and the descriptions that have been made will not be repeated. As used below, the term "module" can implement a combination of software and / or hardware of a predetermined function. Although the devices described in the following embodiments are preferably implemented in software, the implementation of hardware, or a combination of software and hardware, is also possible and conceivable.

[0102] This embodiment provides a circuit configuration device for a switched capacitor circuit, such as Fig. 9 As shown, including:

[0103] An acquisition module 401 is used to acquire the working state of the third switch tube;

[0104] An enabling module 402, configured to stop the cross-coupling module from working when the working state of the third switch tube is enabled;

[0105] The disabling module 403 is used to enable the cross-coupling module to work normally when the working state of the control switch is disabled, so as to neutralize the negative capacitance between the second end of the control switch tube and the third end of the control switch tube.

[0106] The further functional description of each of the above modules and units is the same as that of the above corresponding embodiments and will not be repeated here.

[0107] The circuit configuration device of the switched capacitor circuit in this embodiment is presented in the form of a functional unit, where the unit refers to an ASIC (Application Specific Integrated Circuit) circuit, a processor and memory that executes one or more software or fixed programs, and / or other devices that can provide the above functions.

[0108] The embodiment of the present invention also provides a computer device having the above Fig. 9 The circuit configuration device of the switched capacitor circuit is shown.

[0109] See also Fig.10 , Fig.10 is a schematic diagram of the structure of a computer device provided by an optional embodiment of the present invention, such as Fig.10As shown, the computer device includes: one or more processors 10, a memory 20, and interfaces for connecting various components, including high-speed interfaces and low-speed interfaces. Various components are connected to each other using different buses for communication, and can be installed on a common mainboard or installed in other ways as needed. The processor can process the instructions executed in the computer device, including instructions stored in or on the memory to display the graphical information of the GUI on an external input / output device (such as, a display device coupled to the interface). In some optional embodiments, if necessary, multiple processors and / or multiple buses can be used together with multiple memories and multiple memories. Similarly, multiple computer devices can be connected, and each device provides some necessary operations (for example, as a server array, a group of blade servers, or a multi-processor system). Fig.10 A processor 10 is taken as an example.

[0110] The processor 10 may be a central processing unit, a network processor or a combination thereof. The processor 10 may further include a hardware chip. The hardware chip may be a dedicated integrated circuit, a programmable logic device or a combination thereof. The programmable logic device may be a complex programmable logic device, a field programmable gate array, a general purpose array logic or any combination thereof.

[0111] The memory 20 stores instructions executable by at least one processor 10, so that at least one processor 10 executes the method shown in the above embodiment.

[0112] The memory 20 may include a program storage area and a data storage area, wherein the program storage area may store an operating system, an application required for at least one function; the data storage area may store data created according to the use of the computer device, etc. In addition, the memory 20 may include a high-speed random access memory, and may also include a non-transient memory, such as at least one disk storage device, a flash memory device, or other non-transient solid-state storage device. In some optional embodiments, the memory 20 may optionally include a memory remotely arranged relative to the processor 10, and these remote memories may be connected to the computer device via a network. Examples of the above-mentioned network include, but are not limited to, the Internet, an intranet, a local area network, a mobile communication network, and combinations thereof.

[0113] The memory 20 may include a volatile memory, such as a random access memory; the memory may also include a non-volatile memory, such as a flash memory, a hard disk or a solid state drive; the memory 20 may also include a combination of the above types of memory.

[0114] The computer device also includes an input device 30 and an output device 40. The processor 10, the memory 20, the input device 30 and the output device 40 may be connected via a bus or other means. Fig.10 The example of connecting through bus is taken in the following.

[0115] The input device 30 can receive input digital or character information, and generate key signal input related to the user settings and function control of the computer device, such as a touch screen, a keypad, a mouse, a track pad, a touch pad, an indicator bar, one or more mouse buttons, a trackball, a joystick, etc. The output device 40 may include a display device, an auxiliary lighting device (e.g., an LED) and a tactile feedback device (e.g., a vibration motor), etc. The above-mentioned display device includes but is not limited to a liquid crystal display, a light emitting diode, a display and a plasma display. In some optional embodiments, the display device can be a touch screen.

[0116] The embodiment of the present invention also provides a computer-readable storage medium. The method according to the embodiment of the present invention can be implemented in hardware, firmware, or can be implemented as a computer code that can be recorded in a storage medium, or can be implemented as a computer code that is originally stored in a remote storage medium or a non-temporary machine-readable storage medium and will be stored in a local storage medium through a network download, so that the method described herein can be stored in such software processing on a storage medium using a general-purpose computer, a dedicated processor, or programmable or dedicated hardware. Among them, the storage medium can be a magnetic disk, an optical disk, a read-only storage memory, a random access memory, a flash memory, a hard disk or a solid-state hard disk, etc.; further, the storage medium can also include a combination of the above types of memories. It can be understood that a computer, a processor, a microprocessor controller, or programmable hardware includes a storage component that can store or receive software or computer code. When the software or computer code is accessed and executed by a computer, a processor, or hardware, the method shown in the above embodiment is implemented.

[0117] A part of the present invention may be applied as a computer program product, such as a computer program instruction, which, when executed by a computer, can call or provide the method and / or technical solution according to the present invention through the operation of the computer. Those skilled in the art should understand that the existence of the computer program instruction in a computer-readable medium includes, but is not limited to, a source file, an executable file, an installation package file, etc., and accordingly, the way in which the computer program instruction is executed by the computer includes, but is not limited to: the computer directly executes the instruction, or the computer compiles the instruction and then executes the corresponding compiled program, or the computer reads and executes the instruction, or the computer reads and installs the instruction and then executes the corresponding installed program. Here, the computer-readable medium may be any available computer-readable storage medium or communication medium accessible to the computer.

[0118] Although the embodiments of the present invention have been described in conjunction with the accompanying drawings, those skilled in the art may make various modifications and variations without departing from the spirit and scope of the present invention, and such modifications and variations are all within the scope defined by the appended claims.

Claims

1. A switched capacitor circuit, characterized in that: The circuit includes a switched capacitor module and a cross-coupling module; The switch capacitor module includes a first capacitor, a control switch tube, a second capacitor, a first switch tube and a second switch tube; the first end of the control switch tube is used to receive a first control signal; the second end of the control switch tube is connected to the first output end through the first capacitor; the second end of the control switch tube is also grounded through the first switch tube; The third end of the control switch tube is connected to the second output end through the second capacitor; the third end of the control switch tube is also grounded through the second switch tube; the control ends of the first switch tube and the second switch tube are used to receive control signals; The cross-coupling module is used to control the working state of the cross-coupling module according to the second control signal to neutralize the parasitic capacitance between the second end of the control switch tube and the third end of the control switch tube.

2. The circuit according to claim 1, characterized in that The control switch tube is used to receive a first control signal and control the capacitance to ground of the first output end and the second output end according to the first control signal.

3. The circuit according to claim 1, characterized in that The first switch tube is an n-type metal oxide semiconductor transistor.

4. The circuit according to claim 1, characterized in that The second switch tube is an n-type metal oxide semiconductor transistor.

5. The circuit according to claim 1, characterized in that The cross-coupling module includes a first transistor, a second transistor and a third capacitor; the first transistor is cross-coupled to the second transistor; A first end of the third capacitor is connected to the source of the first transistor, and a second end of the third capacitor is connected to the source of the second transistor; The first transistor and the second transistor are n-type metal oxide semiconductor transistors.

6. The circuit according to claim 5, characterized in that The cross-coupling module further includes a third switch tube, wherein: The third switch tube is used to control the enabling of the cross-coupling module.

7. The circuit according to claim 6, characterized in that The cross-coupling module further includes a first resistor and a second resistor; The first resistor is connected to the drain of the first transistor, the gate of the second transistor and the third switch tube; The second resistor is connected to the drain of the second transistor, the gate of the first transistor and the third switch tube.

8. A voltage-controlled oscillator, characterized in that: The voltage-controlled oscillator comprises a switched capacitor circuit as claimed in any one of claims 1 to 7.

9. A circuit configuration method for a switched capacitor circuit, characterized in that: The method is applied to a voltage-controlled oscillator, wherein the voltage-controlled oscillator includes a switch capacitor circuit, wherein the circuit includes a switch capacitor module and a cross-coupling module; the switch capacitor module includes a first capacitor, a control switch tube, a second capacitor, a first switch tube and a second switch tube; the first end of the control switch tube is used to receive a first control signal; the second end of the control switch tube is connected to the first output end through the first capacitor; the second end of the control switch tube is also grounded through the first switch tube; the third end of the control switch tube is connected to the second output end through the second capacitor; the third end of the control switch tube is also grounded through the second switch tube; the control ends of the first switch tube and the second switch tube are used to receive a control signal; the cross-coupling module is used to control the working state of the cross-coupling module according to the second control signal to neutralize the parasitic capacitance between the second end of the control switch tube and the third end of the control switch tube; The cross-coupling module further includes a third switch tube, and the third switch tube is used to control the enabling of the cross-coupling module; the method includes: Acquire the working state of the third switch tube; When the working state of the third switch tube is enabled, the cross-coupling module stops working; When the working state of the third switch tube is disabled, the cross-coupling module works normally to neutralize the negative capacitance between the second end of the control switch tube and the third end of the control switch tube.

10. A circuit configuration device for a switched capacitor circuit, characterized in that: The device comprises: An acquisition module, used for acquiring the working state of the third switch tube; An enabling module, configured to stop the cross-coupling module from working when the working state of the third switch tube is enabled; The disabling module is used to enable the cross-coupling module to work normally when the working state of the control switch tube is disabled, so as to neutralize the negative capacitance between the second end of the control switch tube and the third end of the control switch tube.

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