An LC oscillator

Abstract

The present application discloses an LC oscillator, including a power supply, a complementary cross-coupled negative resistance amplifier, an inductor, a switched capacitor array, a tuned variable capacitor and a power supply traction compensation circuit. When the voltage of the power supply changes, the voltage of the first output node and the second output node changes with the voltage of the power supply, and the size of the variable capacitor in the power supply traction compensation circuit is adjusted to offset the parasitic capacitance of the complementary cross-coupled negative resistance amplifier, the capacitance in the switched capacitor array and the change in the capacitance size of the tuned variable capacitor. The power supply traction compensation circuit of the present application provides a positive power supply traction compensation coefficient or a negative power supply traction compensation coefficient. The two ends of the power supply traction compensation circuit are directly connected to the first output node and the second output node. By utilizing the change of the output node voltage with the power supply voltage, there is no need to provide an additional bias voltage that changes with the power supply voltage and a constant bias voltage that is independent of the power supply, thereby reducing the circuit complexity, thereby reducing power consumption and area.

Description

Technical Field

[0001] The present invention relates to the technical field of wireless communications, and in particular to an LC oscillator. Background Art

[0002] Since there are various nonlinear capacitors connected to ground in the oscillator, changes in the power supply voltage will also affect the oscillation frequency of the oscillator. This phenomenon is called the power supply pull effect. The output frequency of the voltage-controlled oscillator (VCO) is affected by the change of the power supply voltage Vdd and is expressed as: .in, represents the power traction coefficient, represents the output frequency of the VCO, represents the power supply voltage. An ideal VCO does not change with the power supply voltage. The power traction coefficient changes with the change of It is 0, but it is difficult to achieve in practice.

[0003] In actual oscillators, the power supply is also the main source of noise for the VCO. This noise will have a certain impact on the phase noise of the VCO. Therefore, there are two ways to reduce the impact of this noise: one is to reduce the noise on the power supply, and the other is to reduce the power supply traction coefficient. .

[0004] At present, a Wi-Fi RF transceiver that can be used in three frequency bands of 2.4GHz / 5GHz / 6GHz uses a polarity-variable pushing compensation varactors (PCV) to suppress the main noise contribution caused by power supply noise and DC-DC spurious. Each PCV unit can be configured in different ways and connected to two bias voltages Vb1 and Vb2, thereby adjusting the power supply pulling coefficient of the VCO. The VCO power supply traction factor is obtained by changing the VCO power supply voltage to obtain different frequencies. The number of VCO cycles (integer of reference clock cycles) within a predefined duration can be counted at slightly different power supply voltages. The difference in the count results is the power supply traction factor of the VCO. The search algorithm can find the best PCV configuration to minimize the power supply traction factor of the VCO.

[0005] Disadvantages of this technology:

[0006] 1. A constant voltage that is independent of the power supply is required, which requires additional circuit generation, requiring additional power consumption and area.

[0007] 2. A loop is required and an algorithm is used to find the optimal VCO power supply traction coefficient. The function is complex and requires additional power consumption and area. Summary of the invention

[0008] The purpose of the present invention is to provide an LC oscillator to solve the technical problems in the prior art.

[0009] The various technical effects that can be produced by the optional technical solutions among the various technical solutions provided by the present invention are described in detail below.

[0010] To achieve the above object, the present invention provides the following technical solutions:

[0011] In a first aspect, the present application provides an LC oscillator, comprising a power supply, a complementary cross-coupled negative resistance amplifier, an inductor, a switched capacitor array, a tuning variable capacitor, and a power supply traction compensation circuit; the power supply traction compensation circuit provides a positive power supply traction compensation coefficient or a negative power supply traction compensation coefficient;

[0012] A first end of the complementary cross-coupled negative resistance amplifier is connected to the power supply, a second end of the complementary cross-coupled negative resistance amplifier is grounded, a third end of the complementary cross-coupled negative resistance amplifier is connected to a first output node, and a fourth end of the complementary cross-coupled negative resistance amplifier is connected to a second output node;

[0013] One end of the inductor, one end of the switched capacitor array, one end of the tuned variable capacitor and one end of the power traction compensation circuit are all connected to the first output node, and the other end of the inductor, the other end of the switched capacitor array, the other end of the tuned variable capacitor and the other end of the power traction compensation circuit are all connected to the second output node;

[0014] The inductor, switched capacitor array, tuned variable capacitor, and power supply traction compensation circuit resonate, and the complementary cross-coupled negative resistance amplifier provides negative resistance to maintain oscillation. When the voltage of the power supply changes, the voltages of the first output node and the second output node change along with the voltage of the power supply, and the size of the variable capacitor in the power supply traction compensation circuit is adjusted to offset changes in the parasitic capacitance of the complementary cross-coupled negative resistance amplifier, the capacitance in the switched capacitor array, and the capacitance of the tuned variable capacitor.

[0015] In some embodiments, the power supply traction compensation circuit includes an n-bit compensation array providing a positive power supply traction coefficient and a variable capacitor module providing a negative power supply traction coefficient, and the two ends of the variable capacitor module and the two ends of the n-bit compensation array are respectively connected to the first output node and the second output node.

[0016] In some embodiments, the n-bit compensation array providing the positive power traction coefficient and the variable capacitor module providing the negative power traction coefficient both use P-type variable capacitors, and the n-bit compensation array includes a control word whose size can be adjusted. The size of the variable capacitor in the power traction compensation circuit is adjusted based on the control word to obtain power traction coefficients of different sizes.

[0017] In some embodiments, each of the compensation arrays includes a variable capacitor C11 and a variable capacitor C12 providing a positive coefficient, a fixed capacitor C13 and a fixed capacitor C14, a switch tube M11, a switch tube M12, a switch tube M13 and a switch tube M14, a bias resistor R11, a bias resistor R12, a bias resistor R13, and a bias resistor R14; the positive electrode of the variable capacitor C11 and the positive electrode of the fixed capacitor C13 are connected to the first output node, the negative electrode of the variable capacitor C11 is connected to one end of the bias resistor R11 and the source of the switch tube M11, the drain of the switch tube M11 is connected to the drain of the switch tube M12 and is grounded, the gate of the switch tube M11 and the gate of the switch tube M12 are connected to the control word EN1, the source of the switch tube M12 is connected to one end of the bias resistor R12 and the source of the variable capacitor C12. The negative electrode of the variable capacitor C12 is connected to the second output node and the positive electrode of the fixed capacitor C14, the negative electrode of the fixed capacitor C14 is connected to one end of the bias resistor R14 and the source of the switch tube M14, the source of the switch tube M14 is connected to the drain of the switch tube M13 and then grounded, the gate of the switch tube M14 and the gate of the switch tube M13 are connected to the control voltage ENB1 which is inverse to the control word, the source of the switch tube M13 is connected to one end of the bias resistor R13 and the negative electrode of the fixed capacitor C13, the positive electrode of the fixed capacitor C13 is connected to the first output node, and the other end of the bias resistor R11 and the other end of the bias resistor R12 are both connected to the control voltage ENB1, and the other end of the bias resistor R13 and the other end of the bias resistor R14 are connected to the control word EN1.

[0018] In some embodiments, the variable capacitor module includes a first variable capacitor and a second variable capacitor, the negative electrode of the first variable capacitor and one end of the n-bit compensation array are connected to the first output node, the negative electrode of the second variable capacitor and the other end of the n-bit compensation array are connected to the second output node, the positive electrode of the first variable capacitor and the positive electrode of the second variable capacitor are connected, and the connection point between the positive electrodes of the first variable capacitor and the second variable capacitor is grounded.

[0019] In some embodiments, when the voltage of the power supply increases, the output voltages of the first output node and the second output node increase, and the capacitances of the first variable capacitor and the second variable capacitor increase as the output voltages of the first output node and the second output node increase, so that the output frequencies of the first output node and the second output node decrease.

[0020] In some embodiments, if the voltage of the power supply increases, the output voltages of the first output node and the second output node increase, and the capacitance of the variable capacitors C11 and C12 in the compensation array decreases as the output voltages of the first output node and the second output node increase, so that the output frequencies of the first output node and the second output node increase. According to the negative power supply traction coefficient, the size of the control word is adjusted so that the total capacitance of the compensation array is reduced to meet the requirements of providing a positive power supply traction coefficient to adapt to the negative power supply traction coefficient, thereby maintaining the output frequencies of the first output node and the second output node unchanged.

[0021] In some embodiments, when n=4, the compensation arrays are respectively the first compensation array, the second compensation array, the third compensation array and the fourth compensation array, and the ratio of the positive power coefficients provided by the first compensation array, the second compensation array, the third compensation array and the fourth compensation array is 1:2:4:8.

[0022] In some embodiments, the control word has an adjustment range of 0 to 2 in decimal. n -1; when n=4, the adjustment range of the control word is 0000-1111, that is, 0~15 in decimal.

[0023] In some embodiments, the complementary cross-coupled negative resistance amplifier includes a PMOS cross-pair transistor and an NMOS cross-pair transistor;

[0024] The sources of the PMOS transistor M3 and the PMOS transistor M4 of the PMOS cross-pair transistor are both connected to the power supply, the gate of the PMOS transistor M3 and the drain of the PMOS transistor M4 are both connected to the second output node, and the gate of the PMOS transistor M4 and the drain of the PMOS transistor M3 are both connected to the first output node;

[0025] The sources of the NMOS transistor M1 and the NMOS transistor M2 of the NMOS cross pair are both grounded; the gate of the NMOS transistor M1 is connected to the drain of the NMOS transistor M2 and the second output node, and the gate of the NMOS transistor M2 and the drain of the NMOS transistor M1 are both connected to the first output node.

[0026] Implementing one of the above technical solutions of the present invention has the following advantages or beneficial effects:

[0027] In the LC oscillator of the present application, the power supply traction compensation circuit provides a positive power supply traction compensation coefficient or a negative power supply traction compensation coefficient. When the voltage of the power supply changes, the voltage of the first output node and the second output node changes with the voltage of the power supply, and the size of the variable capacitor in the power supply traction compensation circuit is adjusted, thereby offsetting the parasitic capacitance of the complementary cross-coupled negative resistance amplifier, the capacitance in the switch capacitor array, and the capacitance size of the tuning variable capacitor, so as to reduce the change of the output frequency and reduce the power supply traction coefficient. The two ends of the power pull compensation circuit are directly connected to the first output node and the second output node, and the output node voltage changes with the power supply voltage. There is no need to provide an additional bias voltage that changes with the power supply voltage and a constant bias voltage that is independent of the power supply, thereby reducing circuit complexity, thereby reducing power consumption and area. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. It is obvious that the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative work. In the drawings:

[0029] Figure 1 is a schematic diagram of an LC oscillator according to an embodiment of the present application;

[0030] Figure 2 is a schematic diagram of a power supply pull compensation circuit PCV in an LC oscillator according to an embodiment of the present application;

[0031] Figure 3 is a schematic diagram of a power supply pull compensation circuit PCV in an LC oscillator according to an embodiment of the present application including a 4-bit compensation array;

[0032] Figure 4 is a schematic diagram of the capacitance change simulation result of the power supply pull compensation circuit in the LC oscillator of the embodiment of the present application;

[0033] Figure 5 It is a schematic diagram of simulation results of power traction coefficient before and after compensation by the power traction compensation circuit in the LC oscillator of the embodiment of the present application;

[0034] Figure 6 It is a schematic diagram comparing the output phase noise of the VCO before and after compensation when there is noise in the power supply voltage of the LC oscillator according to the embodiment of the present application. DETAILED DESCRIPTION

[0035] In order to make the purpose, technical solutions and advantages of the present invention clearer, the various exemplary embodiments to be described below will refer to the corresponding drawings, which constitute a part of the exemplary embodiments, wherein various exemplary embodiments that may be used to implement the present invention are described. Unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The implementation methods described in the following exemplary embodiments do not represent all implementation methods consistent with the present disclosure. It should be understood that they are only examples of processes, methods, devices, etc. that are consistent with some aspects of the present disclosure as detailed in the attached claims, and other embodiments may also be used, or the embodiments listed herein may be modified in structure and function without departing from the scope and essence of the present invention.

[0036] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", etc. indicate the orientation or positional relationship based on the drawings, which is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the elements referred to must have a specific orientation, be constructed and operated in a specific orientation. The terms "first", "second", etc. are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. The term "multiple" means two or more. The terms "connected" and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, an integral connection, a mechanical connection, an electrical connection, a communication connection, a direct connection, an indirect connection through an intermediate medium, and can be the internal connection of two elements or the interaction relationship between two elements. The term "and / or" includes any and all combinations of one or more related listed items. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to the specific circumstances.

[0037] In order to illustrate the technical solution of the present invention, a specific embodiment is used below for description, and only the parts related to the embodiment of the present invention are shown.

[0038] Embodiment 1:

[0039] like Figure 1 As shown, the present application provides an LC oscillator, including a power supply VDD, a complementary cross-coupled negative resistance amplifier, an inductor L1, a switch capacitor array SCA (Switch Cap Array), a tuning variable capacitor Varactor and a power traction compensation circuit PCV (Pushing Compensation Varactors). The power traction compensation circuit provides a positive power traction compensation coefficient or a negative power traction compensation coefficient.

[0040] A first terminal of the complementary cross-coupled negative resistance amplifier is connected to a power supply VDD, a second terminal of the complementary cross-coupled negative resistance amplifier is grounded VSS, a third terminal of the complementary cross-coupled negative resistance amplifier is connected to a first output node Voutp, and a fourth terminal of the complementary cross-coupled negative resistance amplifier is connected to a second output node Voutn;

[0041] One end of the inductor L1, one end of the switched capacitor array SCA, one end of the tuned variable capacitor Varactor and one end of the power traction compensation circuit PCV are all connected to the first output node Voutp, and the other end of the inductor L1, the other end of the switched capacitor array SCA, the other end of the tuned variable capacitor Varactor and the other end of the power traction compensation circuit PCV are all connected to the second output node Voutn;

[0042] The inductor L1, the switched capacitor array SCA, the tuned variable capacitor Varactor, and the power traction compensation circuit PCV resonate, and the complementary cross-coupled negative resistance amplifier provides negative resistance to maintain oscillation. When the voltage of the power supply changes, the voltages of the first output node Voutp and the second output node Voutn change with the voltage of the power supply, and the size of the variable capacitor in the power traction compensation circuit PCV is adjusted to offset the changes in the parasitic capacitance of the complementary cross-coupled negative resistance amplifier, the capacitance in the switched capacitor array SCA, and the capacitance of the tuned variable capacitor Varactor.

[0043] The switched capacitor array SCA is used for coarse adjustment of the output frequency, and the tuning variable capacitor Varactor is used for fine adjustment of the output frequency.

[0044] The working principle of the LC oscillator of this application is:

[0045] When the power supply VDD is supplied, the inductor L1, the switched capacitor array SCA, the tuned variable capacitor Varactor, and the power supply traction compensation circuit PCV resonate, and the complementary cross-coupled negative resistance amplifier provides negative resistance to maintain oscillation. When the voltage of the power supply VDD changes, the parasitic capacitance of the complementary cross-coupled negative resistance amplifier, the capacitance in the switched capacitor array SCA, and the capacitance of the tuned variable capacitor Varactor will all change, and these capacitance changes will cause the frequency of the first output node Voutp and the second output node Voutn to change. These unwanted frequency changes will reduce the noise performance of the VCO.

[0046] In order to reduce the change of output frequency, the power traction coefficient is reduced. For the purpose of this invention, the present application adds a power traction compensation circuit PCV. When the voltage of the power supply VDD changes, the voltage of the first output node Voutp and the second output node Voutn changes with the voltage of the power supply VDD. The voltage change of the first output node Voutp and the second output node Voutn will change the size of the variable capacitor in the power traction compensation circuit PCV. The change of the variable capacitor in the power traction compensation circuit PCV can offset the parasitic capacitance of the complementary cross-coupled negative resistance amplifier, the capacitance in the switch capacitor array SCA, and the capacitance change of the tuning variable capacitor Varactor, thereby reducing the change of the output frequency and achieving the reduction of the power traction coefficient. purpose.

[0047] In some embodiments, the power pull compensation circuit PCV includes an n-bit compensation array providing a positive power pull coefficient and a variable capacitor module providing a negative power pull coefficient, and the two ends of the variable capacitor module and the two ends of the n-bit compensation array are respectively connected to the first output node Voutp and the second output node Voutn.

[0048] The positive power traction coefficient is provided by the n-bit compensation array, and the variable capacitor module provides the negative power traction coefficient. The power traction compensation circuit PCV can realize the compensation of the negative power traction coefficient, and can also realize the compensation of the positive power traction coefficient. The two together compensate for the parasitic capacitance of the complementary cross-coupled negative resistance amplifier, the capacitance in the switched capacitor array SCA, and the power traction coefficient caused by the capacitance change of the tuned variable capacitor Varactor. The power supply pulling coefficient caused by the parasitic capacitance of the complementary cross-coupled negative resistance amplifier, the capacitance in the switched capacitor array SCA, and the capacitance change of the tuning variable capacitor Varactor is calculated. The changes in .

[0049] In some embodiments, the n-bit compensation array providing the positive power traction coefficient and the variable capacitor module providing the negative power traction coefficient both use P-type variable capacitors, and the n-bit compensation array includes control words EN1 to ENn whose sizes can be adjusted. The size of the variable capacitor in the power traction compensation circuit PCV is adjusted based on the control words EN1 to ENn to obtain power traction coefficients of different sizes.

[0050] When adjusting the size of the control word, the size of the variable capacitor in the n-bit compensation array can be adjusted to obtain power traction coefficients of different sizes. Combined with the negative power traction coefficient provided by the variable capacitor module, it is possible to offset the parasitic capacitance of the complementary cross-coupled negative resistance amplifier, the capacitance in the switched capacitor array SCA, and the changes in the capacitance size of the tuning variable capacitor Varactor.

[0051] In some embodiments, Figure 2As shown, each compensation array includes a variable capacitor C11 and a variable capacitor C12 providing a positive coefficient, a fixed capacitor C13 and a fixed capacitor C14, a switch tube M11, a switch tube M12, a switch tube M13 and a switch tube M14, a bias resistor R11, a bias resistor R12, a bias resistor R13, and a bias resistor R14; the positive electrode of the variable capacitor C11 and the positive electrode of the fixed capacitor C13 are connected to the first output node Voutp, the negative electrode of the variable capacitor C11 is connected to one end of the bias resistor R11 and the source of the switch tube M11, the drain of the switch tube M11 is connected to the drain of the switch tube M12 and is grounded, the gate of the switch tube M11 and the gate of the switch tube M12 are connected to the control word EN1, and the source of the switch tube M12 is connected to one end of the bias resistor R12 and the negative electrode of the variable capacitor C12. , the positive electrode of the variable capacitor C12 is connected to the second output node Voutn and the positive electrode of the fixed capacitor C14, the negative electrode of the fixed capacitor C14 is connected to one end of the bias resistor R14 and the source of the switch tube M14, the source of the switch tube M14 is connected to the drain of the switch tube M13 and then grounded, the gate of the switch tube M14 and the gate of the switch tube M13 are connected to the control voltage ENB1 which is inverse to the control word EN1, the source of the switch tube M13 is connected to one end of the bias resistor R13 and the negative electrode of the fixed capacitor C13, the positive electrode of the fixed capacitor C13 is connected to the first output node Voutp, and the other end of the bias resistor R11 and the other end of the bias resistor R12 are both connected to the control voltage ENB1, and the other end of the bias resistor R13 and the other end of the bias resistor R14 are connected to the control word EN1. Among them, the variable capacitor C11 and the variable capacitor C12 are both P-type variable capacitors. The fixed capacitor C13 and the fixed capacitor C14 are both fixed capacitors that keep the total capacitance unchanged after the P-type variable capacitor is turned off.

[0052] The control voltage ENB1 is in antiphase with the control word EN1. When the control word EN1 is 1, the control voltage ENB1 is 0, and vice versa.

[0053] A fixed capacitor (C13, C14) is added to each unit of each compensation array to ensure that the total capacitance of the power pull compensation circuit remains unchanged.

[0054] In some embodiments, the variable capacitor module includes a first variable capacitor C01 and a second variable capacitor C02, the negative electrode of the first variable capacitor C01 and one end of the n-bit compensation array are connected to the first output node Voutp, the negative electrode of the second variable capacitor C02 and the other end of the n-bit compensation array are connected to the second output node Voutn, the positive electrode of the first variable capacitor C01 is connected to the positive electrode of the second variable capacitor C02, and the positive electrode connection point of the first variable capacitor C01 and the second variable capacitor C02 is grounded. Wherein, the first variable capacitor C01 and the second variable capacitor C02 are both P-type variable capacitors.

[0055] In some embodiments, when the voltage of the power supply increases, the output voltage of the first output node Voutp and the second output node Voutn increases, and the capacitance of the first variable capacitor and the second variable capacitor increases as the output voltage of the first output node Voutp and the second output node Voutn increases, so that the output frequency of the first output node Voutp and the second output node Voutn decreases.

[0056] In some embodiments, if the voltage of the power supply increases, the size of the control word is adjusted according to the change in the parasitic capacitance of the complementary cross-coupled negative resistance amplifier, the capacitance in the switched capacitor array SCA, and the capacitance size of the tuned variable capacitor Varactor, so that the sum of the change in the capacitance size of the variable capacitor array providing the positive coefficient and the change in the capacitance size of the variable capacitor module matches the change in the parasitic capacitance of the complementary cross-coupled negative resistance amplifier, the capacitance in the switched capacitor array SCA, and the capacitance size of the tuned variable capacitor Varactor. In this way, the change in the parasitic capacitance of the complementary cross-coupled negative resistance amplifier, the capacitance in the switched capacitor array SCA, and the capacitance size of the tuned variable capacitor Varactor can be offset, the change in the output frequency can be reduced, and the power supply traction coefficient can be reduced. purpose.

[0057] Specifically, when the power supply voltage VDD increases, the first output node Voutp and the second output node Voutn will increase with the increase of the power supply voltage, and the capacitance of the first variable capacitor C01 and the second variable capacitor C02 in the variable capacitor module will increase with the increase of the first output node Voutp and the second output node Voutn. The increase of the first variable capacitor C01 and the second variable capacitor C02 will reduce the output frequency and achieve a negative power traction coefficient. When the power supply voltage VDD increases, the voltage of the first output node Voutp and the second output node Voutn will increase with the increase of the power supply voltage, and the capacitance of the variable capacitor C11 and the variable capacitor C12 in the compensation array PCVW1 will decrease with the increase of the voltage of the first output node Voutp and the second output node Voutn, so that the output frequency of the first output node Voutp and the second output node Voutn increases. According to the negative power traction coefficient, the size of the control word EN1 is adjusted to reduce the total capacitance of the compensation array to meet the requirement of providing a positive power traction coefficient to adapt to the negative power traction coefficient, and maintain the output frequency of the first output node Voutp and the second output node Voutn unchanged. This can reduce the power traction coefficient The change of the variable capacitor array in PCVWn is similar. By adjusting the size of the control word EN1-ENn, the appropriate capacitance change of the entire power traction compensation circuit PCV is selected, that is, the appropriate compensation power traction coefficient is selected, so that the total power traction coefficient of the VCO circuit is Close to 0.

[0058] In some embodiments, Figure 3 As shown, when n=4, the compensation arrays are respectively the first compensation array PCVW1, the second compensation array PCVW2, the third compensation array PCVW3 and the fourth compensation array PCVW4, and the ratio of the positive power coefficients provided by the first compensation array PCVW1, the second compensation array PCVW2, the third compensation array PCVW3 and the fourth compensation array PCVW4 is 1:2:4:8.

[0059] The circuit connection relationship in the second compensation array PCVW2, the third compensation array PCVW3 and the fourth compensation array PCVW4 is the same as that in the first compensation array PCVW1, except that the size of each device is proportional to that of the first compensation array PCVW1.

[0060] In some embodiments, when n=4, the control words of the first compensation array, the second compensation array, the third compensation array and the fourth compensation array are EN1, EN2, EN3 and EN4 respectively. The adjustment range of the control words EN1-EN4 is binary 0000-1111, equivalent to decimal 0-15.

[0061] Specifically, the more bits the compensation array has, the larger the capacitance of the connected variable capacitor module is, and the capacitance of the variable capacitor module will change more with the voltage of the power supply, thereby providing a larger positive power supply traction coefficient, and therefore a larger compensation range.

[0062] When n=4, it is a 4-bit compensation array, and the compensation arrays are respectively the first compensation array, the second compensation array, the third compensation array and the fourth compensation array. The ratio of the positive power supply traction coefficient provided by the 4-bit compensation array can be 1:2:4:8. Of course, it can also be other ratios, such as 1:2:3:4, etc., which is not limited here.

[0063] The control word corresponds to the number of bits in the compensation array. If it is an n-bit compensation array, the control word uses n-bit control words EN1~ENn to control PCVW1~PCVWn, so the adjustment range of the control word is decimal 0~2 n -1.

[0064] In some embodiments, the complementary cross-coupled negative resistance amplifier includes a PMOS cross-pair transistor and an NMOS cross-pair transistor;

[0065] The sources of the PMOS transistor M3 and the PMOS transistor M4 of the PMOS cross-pair transistor are both connected to the power supply, the gate of the PMOS transistor M3 and the drain of the PMOS transistor M4 are both connected to the second output node Voutn, and the gate of the PMOS transistor M4 and the drain of the PMOS transistor M3 are both connected to the first output node Voutp;

[0066] The sources of the NMOS transistor M1 and the NMOS transistor M2 of the NMOS cross pair are both grounded; the gate of the NMOS transistor M1 is connected to the drain of the NMOS transistor M2 and the second output node Voutn, and the gate of the NMOS transistor M2 and the drain of the NMOS transistor M1 are both connected to the first output node Voutp.

[0067] The present application embodiment has been experimentally found that:

[0068] like Figure 4 As shown, Figure 4 4 is a schematic diagram of the capacitance change simulation results of the power traction compensation circuit in the LC oscillator of the embodiment of the present application. When the power supply voltage changes from 0.9V to 1.1V, the capacitance change simulation results of the power traction compensation circuit in the present invention when the control word is equal to decimal 0, 7, and 15 are shown in Figure 4. When the control word is equal to decimal 0, the power supply changes from 0.9V to 1V, and the capacitance change of the compensation circuit is 2.9fF. When the control word is equal to decimal 7, the power supply changes from 0.9V to 1V, and the capacitance change of the compensation circuit is -2.3fF. When the control word is equal to decimal 15, the power supply changes from 0.9V to 1V, and the capacitance change of the compensation circuit is -8.5fF. Therefore, the power traction compensation circuit of the present invention can realize the compensation of the negative power supply traction coefficient, and can also realize the compensation of the positive power supply traction coefficient.

[0069] like Figure 5 shown. Figure 5 A schematic diagram showing simulation results of the power pull coefficient before and after compensation by the power pull compensation circuit in the LC oscillator proposed in an embodiment of the present application. Figure 5 It is shown that in the LC oscillator, when the supply voltage is 1V, the uncompensated power supply pull coefficient The power traction coefficient after compensation is -78.82MHz / V. It is 0.939MHz / V.

[0070] When there is noise in the power supply voltage of the LC oscillator, the output phase noise of the VCO before and after compensation is compared. Figure 6 As shown in the figure, the phase noise of the VCO at 1MHz is -118.8 dBc / Hz before compensation and -121.3 dBc / Hz after compensation. After compensation, the phase noise is significantly improved and the power supply noise is suppressed.

[0071] In the embodiment of the present application, the power supply traction compensation circuit provides a positive power supply traction compensation coefficient or a negative power supply traction compensation coefficient. When the voltage of the power supply changes, the voltage of the first output node and the second output node changes with the voltage of the power supply, and the size of the variable capacitor in the power supply traction compensation circuit is adjusted, thereby offsetting the parasitic capacitance of the complementary cross-coupled negative resistance amplifier, the capacitance in the switch capacitor array, and the capacitance size of the tuning variable capacitor, so as to reduce the change of the output frequency and reduce the power supply traction coefficient. The two ends of the power pull compensation circuit are directly connected to the first output node and the second output node, and the output node voltage changes with the power supply voltage. There is no need to provide an additional bias voltage that changes with the power supply voltage and a constant bias voltage that is independent of the power supply, thereby reducing circuit complexity, thereby reducing power consumption and area.

[0072] The embodiment is only a special case and does not indicate that the present application is implemented in such a way.

[0073] The above description is only the preferred embodiment of the present invention. It is known to those skilled in the art that various changes or equivalent substitutions may be made to these features and embodiments without departing from the spirit and scope of the present invention. In addition, under the teachings of the present invention, these features and embodiments may be modified to adapt to specific circumstances and materials without departing from the spirit and scope of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed herein, and all embodiments falling within the scope of the claims of this application belong to the protection scope of the present invention.

Claims

1. An LC oscillator, characterized in that: It includes a power supply, a complementary cross-coupled negative resistance amplifier, an inductor, a switch capacitor array, a tuning variable capacitor and a power supply traction compensation circuit; the power supply traction compensation circuit provides a positive power supply traction compensation coefficient or a negative power supply traction compensation coefficient; A first end of the complementary cross-coupled negative resistance amplifier is connected to the power supply, a second end of the complementary cross-coupled negative resistance amplifier is grounded, a third end of the complementary cross-coupled negative resistance amplifier is connected to a first output node, and a fourth end of the complementary cross-coupled negative resistance amplifier is connected to a second output node; One end of the inductor, one end of the switched capacitor array, one end of the tuned variable capacitor and one end of the power traction compensation circuit are all connected to the first output node, and the other end of the inductor, the other end of the switched capacitor array, the other end of the tuned variable capacitor and the other end of the power traction compensation circuit are all connected to the second output node; The inductor, switched capacitor array, tuned variable capacitor, and power supply traction compensation circuit resonate, and the complementary cross-coupled negative resistance amplifier provides negative resistance to maintain oscillation. When the voltage of the power supply changes, the voltages of the first output node and the second output node change along with the voltage of the power supply, and the size of the variable capacitor in the power supply traction compensation circuit is adjusted to offset changes in the parasitic capacitance of the complementary cross-coupled negative resistance amplifier, the capacitance in the switched capacitor array, and the capacitance of the tuned variable capacitor.

2. The LC oscillator according to claim 1, characterized in that: The power traction compensation circuit includes an n-bit compensation array providing a positive power traction coefficient and a variable capacitor module providing a negative power traction coefficient. Both ends of the variable capacitor module and both ends of the n-bit compensation array are connected to the first output node and the second output node respectively.

3. The LC oscillator according to claim 2, characterized in that: The n-bit compensation array providing the positive power traction coefficient and the variable capacitor module providing the negative power traction coefficient both use P-type variable capacitors. The n-bit compensation array includes a control word that can adjust the size. The size of the variable capacitor in the power traction compensation circuit is adjusted based on the control word to obtain power traction coefficients of different sizes.

4. The LC oscillator according to claim 3, characterized in that: Each compensation array includes a variable capacitor C11 and a variable capacitor C12 providing a positive coefficient, a fixed capacitor C13 and a fixed capacitor C14, a switch tube M11, a switch tube M12, a switch tube M13 and a switch tube M14, a bias resistor R11, a bias resistor R12, a bias resistor R13, and a bias resistor R14; the positive electrode of the variable capacitor C11 and the positive electrode of the fixed capacitor C13 are connected to the first output node, the negative electrode of the variable capacitor C11 is connected to one end of the bias resistor R11 and the source of the switch tube M11, the drain of the switch tube M11 is connected to the drain of the switch tube M12 and is grounded, the gate of the switch tube M11 and the gate of the switch tube M12 are connected to the control word EN1, the source of the switch tube M12 is connected to one end of the bias resistor R12 and the negative electrode of the variable capacitor C12 , the positive electrode of the variable capacitor C12 is connected to the second output node and the positive electrode of the fixed capacitor C14, the negative electrode of the fixed capacitor C14 is connected to one end of the bias resistor R14 and the source of the switch tube M14, the source of the switch tube M14 and the drain of the switch tube M13 are connected and then grounded, the gate of the switch tube M14 and the gate of the switch tube M13 are connected to the control voltage ENB1 which is inverse to the control word, the source of the switch tube M13 is connected to one end of the bias resistor R13 and the negative electrode of the fixed capacitor C13, the positive electrode of the fixed capacitor C13 is connected to the first output node, and the other end of the bias resistor R11 and the other end of the bias resistor R12 are both connected to the control voltage ENB1, and the other end of the bias resistor R13 and the other end of the bias resistor R14 are connected to the control word EN1.

5. The LC oscillator according to claim 4, characterized in that: The variable capacitor module includes a first variable capacitor and a second variable capacitor, the negative electrode of the first variable capacitor and one end of the n-bit compensation array are connected to the first output node, the negative electrode of the second variable capacitor and the other end of the n-bit compensation array are connected to the second output node, the positive electrode of the first variable capacitor and the positive electrode of the second variable capacitor are connected, and the connection point between the positive electrodes of the first variable capacitor and the second variable capacitor is grounded.

6. The LC oscillator according to claim 5, characterized in that: When the voltage of the power supply increases, the output voltages of the first output node and the second output node increase, and the capacitances of the first variable capacitor and the second variable capacitor increase as the output voltages of the first output node and the second output node increase, so that the output frequencies of the first output node and the second output node decrease.

7. The LC oscillator according to claim 4, characterized in that: If the voltage of the power supply increases, the output voltages of the first output node and the second output node increase, and the capacitance of the variable capacitors C11 and C12 in the compensation array decreases as the output voltages of the first output node and the second output node increase, so that the output frequencies of the first output node and the second output node increase. According to the negative power supply traction coefficient, the size of the control word is adjusted so that the total capacitance of the compensation array is reduced to meet the requirement of providing a positive power supply traction coefficient to adapt to the negative power supply traction coefficient, thereby maintaining the output frequencies of the first output node and the second output node unchanged.

8. The LC oscillator according to claim 2, characterized in that: When n=4, the compensation arrays are respectively the first compensation array, the second compensation array, the third compensation array and the fourth compensation array, and the ratio of the positive power coefficients provided by the first compensation array, the second compensation array, the third compensation array and the fourth compensation array is 1:2:4:

8.

9. The LC oscillator according to claim 3, characterized in that: The adjustment range of the control word is decimal 0~2 n -1; when n=4, the adjustment range of the control word is 0000-1111, which is 0~15 in decimal.

10. The LC oscillator according to any one of claims 1 to 9, characterized in that: The complementary cross-coupled negative resistance amplifier comprises a PMOS cross-pair transistor and an NMOS cross-pair transistor; The sources of the PMOS transistor M3 and the PMOS transistor M4 of the PMOS cross-pair transistor are both connected to the power supply, the gate of the PMOS transistor M3 and the drain of the PMOS transistor M4 are both connected to the second output node, and the gate of the PMOS transistor M4 and the drain of the PMOS transistor M3 are both connected to the first output node; The sources of the NMOS transistor M1 and the NMOS transistor M2 of the NMOS cross pair are both grounded; the gate of the NMOS transistor M1 is connected to the drain of the NMOS transistor M2 and the second output node, and the gate of the NMOS transistor M2 and the drain of the NMOS transistor M1 are both connected to the first output node.

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