A voltage-controlled oscillator with inverse class-F and three-point dual-mode operation

Abstract

The present application provides a voltage-controlled oscillator with inverse class F and three-point dual-mode operation. The oscillator is a single-core oscillator and includes: an active negative resistance transistor pair, a passive inductor group, a frequency adjustment module, a first switch group, and a second switch group; the passive inductor group and the frequency adjustment module form a passive resonant cavity; when the first switch group is closed and the second switch group is disconnected, the active negative resistance transistor pair is connected to the passive inductor group in a differential manner to form an inverse class F oscillator; and when the first switch group is disconnected and the second switch group is closed, the active negative resistance transistor pair is connected to the passive inductor group in a common-mode parallel manner to form a three-point oscillator. The technical solution provided by the present application avoids the problem of mismatch between cores in existing multi-core oscillators causing the resonant cavity impedance peak to deviate from the preset value, and further broadens the frequency adjustment range of the single-core oscillator on the basis of low phase noise.

Description

Technical Field

[0001] This document relates to the field of radio frequency integrated circuit technology, and in particular to a voltage-controlled oscillator with inverse class-F and three-point dual-mode operation. Background Art

[0002] The communications industry needs to integrate multi-standard wireless transceivers into a single chip, so the voltage-controlled oscillator is required to have a wide frequency coverage to achieve seamless full-range frequency synthesis.

[0003] Current voltage-controlled oscillators (VCOs) with a wide frequency adjustment range are typically implemented using a multi-core, multi-mode solution. This multi-core, multi-mode operation significantly extends the VCO's FTR (frequency adjustment range). The primary advantage of this solution is the coupling of multiple identical VCO cores, which improves the VCO's frequency adjustment range and phase noise. However, this approach inevitably has some disadvantages:

[0004] 1. The power consumption of the voltage-controlled oscillator circuit increases exponentially. Although coupling multiple VCO cores can improve the circuit's phase noise performance, the increased power consumption brought by multiple VCOs means that the voltage-controlled oscillator's FoM (Figure of Merit) remains unchanged.

[0005] 2. Mismatch between different VCO cores. Mismatch between cores can cause the resonant cavity impedance peak to deviate from the preset value, making it impossible to achieve seamless full-range frequency synthesis.

[0006] 3. The Q value (quality factor) of the resonant cavity decreases in high-frequency mode. In high-frequency mode, the magnetic flux generated between the coupled inductors cancels each other, reducing the effective inductance value, but the loss remains almost unchanged, thus reducing the equivalent quality factor of the resonant cavity.

[0007] Therefore, it is necessary to design a voltage-controlled oscillator that can simultaneously achieve a wide frequency adjustment range and low phase noise to meet the needs of today's multi-standard integrated transceiver systems. Summary of the Invention

[0008] In view of the above analysis, the present application aims to propose a voltage-controlled oscillator with inverse class F and three-point dual-mode operation, which realizes mode switching only in one oscillator core through switch switching and can achieve frequency tuning in two modes.

[0009] In a first aspect, one or more embodiments of this specification provide a voltage-controlled oscillator with inverse class-F and three-point dual-mode operation, wherein the oscillator is a single-core oscillator and includes: an active negative resistance transistor pair, a passive inductor group, a frequency adjustment module, a first switch group, and a second switch group;

[0010] The passive inductor group and the frequency adjustment module form a passive resonant cavity;

[0011] When the first switch group is closed and the second switch group is open, the active negative resistance transistor pair is connected to the passive resonant cavity in a differential form to form an inverse class F oscillator; and

[0012] When the first switch group is disconnected and the second switch group is closed, the active negative resistance transistor pair is connected to the passive resonant cavity in a common-mode parallel manner to form a three-point oscillator.

[0013] Furthermore, the frequency adjustment module is used to adjust the capacitance value connected to the resonant cavity.

[0014] Furthermore, the frequency adjustment module includes a set of variable capacitors and multiple sets of digitally controlled capacitor arrays;

[0015] The digitally controlled capacitor arrays are connected in parallel; and

[0016] The variable capacitors are connected in series and then in parallel with the digitally controlled capacitor array.

[0017] Furthermore, the active negative resistance transistor pair includes two NMOS transistors;

[0018] The frequency adjustment module includes a first adjustment submodule and a second adjustment submodule;

[0019] Two ends of the first regulating submodule are respectively connected to two ends of the passive inductor group; and

[0020] Two ends of the second regulating submodule are respectively connected to the gates of the two NMOS tubes.

[0021] Furthermore, when the working mode is three-point, the passive inductor group, the first regulating submodule and the second regulating submodule enable a capacitor or a capacitor to exist between any two poles of each of the two NMOS tubes.

[0022] Furthermore, the active negative resistance transistor pair includes two NMOS transistors; and

[0023] The preparation process of the NMOS tube is a fully depleted silicon-on-insulator process.

[0024] Furthermore, the NMOS tube adjusts the substrate external bias voltage V FD , so as to adjust the threshold voltage of the NMOS tube, thereby adjusting the circuit operating frequency and power consumption.

[0025] Furthermore, the passive inductor group includes two mutually coupled differential inductors and a common mode inductor; and

[0026] The center of the connection between the two differential inductors is connected to one end of the common mode inductor.

[0027] Furthermore, the active negative resistance transistor pair includes two NMOS transistors;

[0028] The passive inductor group includes a differential inductor group and a common mode inductor;

[0029] The first switch group includes: switch SWA1, switch SWA2 and switch SWA3;

[0030] One end of the switch SWA1 is respectively connected to one end of the differential inductor group and the drain of one NMOS transistor in the active negative resistance transistor pair, and the other end is connected to the gate of one NMOS transistor in the active negative resistance transistor pair;

[0031] One end of the switch SWA2 is respectively connected to the other end of the differential inductor group and the drain of one NMOS transistor in the active negative resistance transistor pair, and the other end is connected to the gate of the other NMOS transistor in the active negative resistance transistor pair; and

[0032] One end of the switch SWA3 is connected to one end of the common-mode inductor, and the other end is connected to a power supply.

[0033] Furthermore, the active negative resistance transistor pair includes two NMOS transistors;

[0034] The passive inductor group includes two mutually coupled differential inductors and a common mode inductor;

[0035] The second switch group includes: switch SWB1, switch SWB2, switch SWB3 and switch SWB4;

[0036] The two ends of the switch SWB1 are respectively connected to the gates of the two NMOS transistors in the active negative resistance transistor pair;

[0037] One end of the switch SWB2 is respectively connected to one end of the differential inductor group and the drain of one NMOS transistor in the active negative resistance transistor pair, and the other end is respectively connected to the other end of the differential inductor group and the drain of the other NMOS transistor in the active negative resistance transistor pair;

[0038] One end of the switch SWB3 is respectively connected to one end of the switch SWB2, one end of the differential inductor group, and the drain of an NMOS transistor in the active negative resistance transistor pair, and the other end is connected to a power supply; and

[0039] One end of the switch SWB4 is respectively connected to one end of the switch SWB1 and the gate of the other NMOS transistor in the active negative resistance transistor pair, and the other end is connected to one end of the common mode inductor.

[0040] Compared with the existing technology, this application can at least achieve the following technical effects:

[0041] The voltage-controlled oscillator of the present application is a single-core oscillator, that is, it only uses one active negative resistance core, realizes the tuning of two different operating frequency bands, and avoids the problem of the resonant cavity impedance peak deviating from the preset value due to the mismatch between multiple cores. And the first switch group and the second switch group are used to realize two connection modes of the active negative resistance transistor pair and the passive resonant cavity. Among them, when the first switch group is closed and the second switch group is disconnected, the active negative resistance transistor pair is connected to the passive resonant cavity in a differential form, corresponding to the inverse F-class mode. When the first switch group is disconnected and the second switch group is closed, the active negative resistance transistor pair is connected to the passive resonant cavity in the form of common-mode parallel connection, corresponding to a three-point type. By the above method, one core corresponds to dual modes, which avoids the problem of mismatch between multiple cores compared to the existing multi-core multi-mode oscillator, reduces circuit power consumption, and improves the frequency adjustment range of the single-core oscillator. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] In order to more clearly illustrate one or more embodiments of this specification or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments recorded in this specification. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0043] Figure 1 A circuit diagram of a voltage-controlled oscillator provided for one or more embodiments of this specification;

[0044] Figure 2 A schematic diagram of the input impedance of the resonant cavity in the inverse class F operating mode provided by one or more embodiments of this specification;

[0045] Figure 3 A schematic diagram of the input impedance of the resonant cavity in a three-point type working mode provided by one or more embodiments of this specification;

[0046] Figure 4 An equivalent circuit diagram of a differential mode resonant cavity provided for one or more embodiments of this specification;

[0047] Figure 5 An equivalent circuit diagram of a common mode resonant cavity provided for one or more embodiments of this specification;

[0048] Figure 6 A circuit diagram of a frequency adjustment module provided in one or more embodiments of this specification;

[0049] Figure 7The frequency adjustment range provided for one or more embodiments of this specification;

[0050] Figure 8 A circuit diagram of an inverse class-F voltage-controlled oscillator provided for one or more embodiments of this specification;

[0051] Figure 9 A schematic diagram of a DM (differential mode) path of a frequency adjustment module in an inverse class F mode provided in one or more embodiments of this specification;

[0052] Figure 10 A schematic diagram of a CM (common mode) path of a frequency adjustment module in an inverse class F mode provided in one or more embodiments of this specification;

[0053] Figure 11 A circuit diagram of a three-point voltage-controlled oscillator provided for one or more embodiments of this specification;

[0054] Figure 12 This is an equivalent circuit diagram of a frequency adjustment module in a three-point mode provided in one or more embodiments of this specification. DETAILED DESCRIPTION

[0055] In order to enable those skilled in the art to better understand the technical solutions in one or more embodiments of this specification, the technical solutions in one or more embodiments of this specification will be clearly and completely described below in conjunction with the drawings in one or more embodiments of this specification. Obviously, the described embodiments are only part of the embodiments of this specification, not all of the embodiments. Based on one or more embodiments of this specification, all other embodiments obtained by ordinary technicians in this field without making creative efforts should fall within the scope of protection of this document.

[0056] The embodiment of the present application provides a voltage controlled oscillator with inverse F-class and three-point dual-mode operation, the oscillator is in single-core mode, such as Figure 1 As shown, it includes: an active negative resistance transistor pair, a passive inductor group, a frequency adjustment module, a first switch group and a second switch group;

[0057] The passive inductor group and the frequency adjustment module form a passive resonant cavity;

[0058] When the first switch group is closed and the second switch group is open, the active negative resistance transistor pair is connected to the passive resonant cavity in a differential form to form an inverse class F oscillator; and

[0059] When the first switch group is disconnected and the second switch group is closed, the active negative resistance transistor pair is connected to the passive resonant cavity in a common-mode parallel connection to form a three-point oscillator.

[0060] Among them, the active negative resistance transistor pair is two NMOS tubes N <0> and N <1> . The passive inductor group includes two mutually coupled differential inductors (La and Lb) and a common-mode inductor (LT). The center of the connection between the two differential inductors is connected to one end of the common-mode inductor. The first switch group includes: switch SWA1, switch SWA2 and switch SWA3. The second switch group includes: switch SWB1, switch SWB2, switch SWB3 and switch SWB4. It should be noted that the above embodiment is a preferred solution, and those skilled in the art can select other combinations of switch groups according to actual conditions to achieve inverse F class and three-point switching.

[0061] Inverse F-type and three-point type are categories of voltage-controlled oscillators. Among them, the inverse F-type oscillator improves phase noise by introducing the second harmonic. Specifically, in the inverse F-type working mode, the resonant cavity provides both the fundamental impedance peak and the second harmonic impedance peak. The impedance peak provided by the second harmonic makes the voltage waveform at the drain of the transistor close to a half-sine wave, thereby reducing phase noise. A three-point oscillator refers to a capacitor or inductor (feedback part) whose three ends are connected to the three poles of the transistor respectively. Among them, the input impedance of the resonant cavity in the inverse F-type working mode is as follows: Figure 2 As shown, the input impedance of the resonant cavity in the three-point working mode is as follows: Figure 3 shown.

[0062] In the embodiment of the present application, the differential inductors La and Lb have an inductance value of L. The inductance value of the common mode inductor LT is LH. There is a coupling coefficient k between the differential inductors, and the common mode inductor LT is connected at the center. When the circuit is working, in the differential mode path, Figure 4 As shown, the common mode inductance LT is ignored, and the equivalent inductance of the resonant cavity is 2(1+k)L; in the common mode path, as Figure 5 As shown, the common-mode inductor LT is connected to the resonant cavity, but the magnetic fluxes generated by the differential inductors cancel each other out, reducing the effective inductance. At this time, the equivalent inductance of the resonant cavity is (1-k)L / 2+LH.

[0063] In the embodiments of this application, Figure 6 As shown, the frequency adjustment module includes a group of variable capacitors and multiple groups of digitally controlled capacitor arrays; the digitally controlled capacitor arrays are connected in parallel; the variable capacitors are connected in series and then in parallel with the digitally controlled capacitor arrays.

[0064] Specifically, the selection signal SW is changed using <0> -SW <n>, the size and number of digital control capacitors connected to the passive inductor group can be adjusted. By adjusting the control voltage V C , the variable capacitor Cvar can be adjusted <0> , Cvar <1> The effective capacitance of the capacitor is adjusted to achieve continuous and precise control of the capacitance value connected to the resonant cavity. By adjusting the variable capacitor and the digitally controlled capacitor array, the peak impedance of the passive topology module's input impedance and its corresponding frequency can be precisely changed, thereby adjusting the output frequency of the voltage-controlled oscillator.

[0065] It should be noted that each group of digitally controlled capacitor arrays includes: 1 inverter INV <n>, 2 switching transistors (Nn <0> and Nn <1> ), 2 capacitors (Cn <0> and Cn <1> ), 2 resistors (Rn <0> and Rn <1> ). V b <0> -V b <n>, Vc is the DC bias point.

[0066] Preferably, the capacitance value of the passive inductor group is adjusted based on the above-mentioned frequency adjustment module to achieve the following Figure 7 The frequency coverage shown is Figure 7 It can be seen that the operating frequencies of the inverse class-F oscillator and the three-point oscillator have an overlapping range, so when switching the oscillator operating mode, seamless full-range frequency adjustment can be achieved.

[0067] In the embodiment of this application, combined with Figures 8-11 A detailed description of the working mode of the voltage controlled oscillator:

[0068] like Figure 8 As shown, when SWA1-SWA3 are connected and SWB1-SWB4 are disconnected, the voltage-controlled oscillator is in an inverse F-class working state. At this time, one end of the switch SWA1 is connected to one end of the differential inductor group (La and Lb) and the drain of an NMOS tube in the active negative resistance transistor pair, and the other end is connected to the gate of an NMOS tube in the active negative resistance transistor pair. One end of the switch SWA2 is connected to the other end of the differential inductor group and the drain of an NMOS tube in the active negative resistance transistor pair, and the other end is connected to the gate of the other NMOS tube in the active negative resistance transistor pair. One end of the switch SWA3 is connected to one end of the common-mode inductor, and the other end is connected to the power supply. At this time, the baseband signal is transmitted in the DM (differential mode) path as shown in FIG. Figure 9 As shown, the second harmonic signal is transmitted through the CM (common mode) path as shown in Figure 10 shown.

[0069] In the inverse Class F operating state, the resonant cavity provides fundamental impedance peaks and second harmonic impedance peaks. Through second harmonic frequency modulation, a stronger second harmonic impedance peak can be generated at the drain node of the negative resistance transistor, thereby enhancing the second harmonic component of the transistor drain voltage and making the generated oscillating voltage closer to a half-sine signal, thereby reducing the phase noise of the circuit.

[0070] like Figure 11 As shown, when SWA1-SWA3 are disconnected and SWB1-SWB4 are connected, the voltage-controlled oscillator is in a three-point operating state. At this time, the two ends of switch SWB1 are respectively connected to the gates of the two NMOS transistors in the active negative resistance transistor pair; one end of switch SWB2 is respectively connected to one end of the differential inductor group and the drain of one NMOS transistor in the active negative resistance transistor pair, and the other end is respectively connected to the other end of the differential inductor group and the drain of the other NMOS transistor in the active negative resistance transistor pair; one end of switch SWB3 is respectively connected to one end of switch SWB2, one end of the differential inductor group, and the drain of one NMOS transistor in the active negative resistance transistor pair, and the other end is connected to the power supply; one end of switch SWB4 is respectively connected to one end of switch SWB1 and the gate of the other NMOS transistor in the active negative resistance transistor pair, and the other end is connected to one end of the common-mode inductor. At the same time, the passive inductor group, the first regulating submodule, and the second regulating submodule ensure that an inductor or capacitor exists between any two poles of each of the two NMOS transistors. The corresponding frequency adjustment module works in CM (common mode) mode, at this time the baseband signal is transmitted through the CM (common mode) path. Figure 10 shown.

[0071] In the three-point operating mode, the resonant cavity provides only the fundamental impedance peak. This allows the negative resistance transistors to operate in common-mode parallel, increasing their effective transconductance and providing greater gain, simplifying oscillation startup conditions, and enhancing output swing. Furthermore, the operating frequency bands of the two modes overlap, ultimately forming a wider frequency band and achieving a wide frequency adjustment range.

[0072] It should be noted that in order to highlight the three-point oscillation circuit structure, Figure 11 For NMOS tube (N <0> and N <1> ) are combined. In the three-point oscillator, the DC bias point (Vb <0> -Vb <n>, Vc) is considered to be grounded. At this time, the equivalent circuit diagram of the frequency regulation module is as follows Figure 12 As shown. Among them, the ground point is the DC bias point Vb <0> -Vb <n>, Vc, and the rest of the components remain unchanged.

[0073] Preferably, the NMOS tube circuit design is based on FDSOI technology. Based on the above technology, the substrate of the NMOS tube can be externally biased V FD By changing the external bias voltage V FD , the threshold voltage of the active negative resistance transistor pair can be adjusted, thereby regulating the operating response speed and power consumption of the voltage-controlled oscillator circuit.

[0074] In summary, the present application realizes two different operating modes in the case of a single core by switching the connection method between the resonant cavity and the negative resistance transistor. When working in the inverse F-class mode, the phase noise of the circuit is reduced by the second harmonic tuning technology. When working in the three-point mode, the oscillation startup is simplified and the output swing is enhanced by the parallel enhancement of the negative resistance transistor. Compared with the multi-core multi-mode VCO, the circuit structure of the present application is simpler, and the single-core operation mode avoids the mismatch between different oscillation cores, which causes the impedance peak to deviate from the preset value. Compared with the four-mode four-core VCO implemented by mode splitting technology, the present application only needs to work one active negative resistance core at the same time, the circuit power consumption is lower, and fewer mode switching switches are required.

[0075] It should also be noted that the terms "comprises," "includes," or any other variations thereof are intended to encompass non-exclusive inclusion, such that a process, method, commodity, or apparatus that includes a list of elements includes not only those elements but also other elements not explicitly listed, or includes elements inherent to such process, method, commodity, or apparatus. In the absence of further limitations, an element defined by the phrase "comprising a..." does not preclude the presence of other identical elements in the process, method, commodity, or apparatus that includes the element.

[0076] The various embodiments in this specification are described in a progressive manner. Similar parts between the various embodiments can be referred to in conjunction with each other. Each embodiment focuses on the differences between the other embodiments. In particular, the system embodiments are generally similar to the method embodiments, so the description is relatively simple. For relevant parts, refer to the description of the method embodiments.

[0077] The foregoing description is merely an example of the present invention and is not intended to limit the present invention. Persons skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be included within the scope of the claims herein.< / n> < / n> < / n> < / n> < / n>

Claims

1. A voltage controlled oscillator with inverse class F and three-point dual-mode operation, characterized in that: The oscillator is a single-core oscillator, comprising: an active negative resistance transistor pair, a passive inductor group, a frequency adjustment module, a first switch group, and a second switch group; The passive inductor group and the frequency adjustment module form a passive resonant cavity; When the first switch group is closed and the second switch group is open, the active negative resistance transistor pair is connected to the passive resonant cavity in a differential form to form an inverse class F oscillator; and When the first switch group is disconnected and the second switch group is closed, the active negative resistance transistor pair is connected to the passive resonant cavity in a common-mode parallel connection to form a three-point oscillator; The active negative resistance transistor pair includes two NMOS transistors; The passive inductor group includes a differential inductor group and a common mode inductor; The first switch group includes: switch SWA1, switch SWA2 and switch SWA3; One end of the switch SWA1 is respectively connected to one end of the differential inductor group and the drain of one NMOS transistor in the active negative resistance transistor pair, and the other end is connected to the gate of one NMOS transistor in the active negative resistance transistor pair; One end of the switch SWA2 is respectively connected to the other end of the differential inductor group and the drain of one NMOS transistor in the active negative resistance transistor pair, and the other end is connected to the gate of the other NMOS transistor in the active negative resistance transistor pair; and One end of the switch SWA3 is connected to one end of the common-mode inductor, and the other end is connected to the power supply; The second switch group includes: switch SWB1, switch SWB2, switch SWB3 and switch SWB4; One end of the switch SWB1 is connected to the gate of one NMOS transistor in the active negative resistance transistor pair, and the other end of the switch SWB1 is connected to the gate of the other NMOS transistor in the active negative resistance transistor pair; One end of the switch SWB2 is respectively connected to one end of the differential inductor group and the drain of one NMOS transistor in the active negative resistance transistor pair, and the other end is respectively connected to the other end of the differential inductor group and the drain of the other NMOS transistor in the active negative resistance transistor pair; One end of the switch SWB3 is respectively connected to one end of the switch SWB2, one end of the differential inductor group, and the drain of an NMOS transistor in the active negative resistance transistor pair, and the other end is connected to a power supply; and One end of the switch SWB4 is respectively connected to one end of the switch SWB1 and the gate of the other NMOS transistor in the active negative resistance transistor pair, and the other end is connected to one end of the common mode inductor.

2. The voltage-controlled oscillator according to claim 1, wherein: The frequency adjustment module is used to adjust the capacitance value connected to the passive resonant cavity.

3. The voltage-controlled oscillator according to claim 2, wherein: The frequency adjustment module includes a set of variable capacitors and multiple sets of digitally controlled capacitor arrays; The digitally controlled capacitor arrays are connected in parallel; and The variable capacitors are connected in series and then in parallel with the digitally controlled capacitor array.

4. The voltage controlled oscillator according to claim 2, wherein: The active negative resistance transistor pair includes two NMOS transistors; The frequency adjustment module includes a first adjustment submodule and a second adjustment submodule; Two ends of the first regulating submodule are respectively connected to two ends of the passive inductor group; and One end of the second regulating submodule is connected to the gate of an NMOS transistor, and the other end of the second regulating submodule is connected to the gate of another NMOS transistor.

5. The voltage controlled oscillator according to claim 4, wherein: When the working mode is three-point, the passive inductor group, the first regulating submodule and the second regulating submodule enable an inductor or a capacitor to exist between any two poles of each of the two NMOS tubes.

6. The voltage controlled oscillator according to claim 1, wherein: The active negative resistance transistor pair includes two NMOS transistors; and The preparation process of the NMOS tube is a fully depleted silicon-on-insulator process.

7. The voltage controlled oscillator according to claim 6, wherein: The NMOS tube is biased by adjusting the substrate external bias voltage V FD , so as to adjust the threshold voltage of the NMOS tube.

8. The voltage controlled oscillator according to claim 1, wherein: The passive inductor group includes two mutually coupled differential inductors and a common mode inductor; and The center of the connection between the two mutually coupled differential inductors is connected to one end of the common mode inductor.

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