Four-phase high-robustness oscillator for high-speed radio frequency communication

Abstract

The invention relates to a four-phase high-robustness oscillator for high-speed radio frequency communication. The four-phase high-robustness oscillator comprises two sub-circuits with the same structure, each sub-circuit comprises a switched capacitor array and two resonance units with the same structure; the input end of each resonance unit in one sub-circuit is connected with the output ends of the two resonance units in the other sub-circuit; each resonance unit comprises a protection capacitor subunit, an amplitude adjustment subunit, an active core subunit and a series resonant cavity subunit; the amplitude adjusting subunit and the bias voltage are used for reducing the input voltage amplitude of the control end of the active core subunit. The input voltage amplitude of the control end of the active core subunit is reduced through the amplitude adjusting subunit and the bias voltage, so that the voltage difference of each end of an active device in the active core subunit is lower than the power supply voltage, the large voltage amplitude is controlled in a passive device, and the reliability is greatly improved while low phase noise is realized.

Description

Technical Field

[0001] The present invention belongs to the technical field of integrated circuits, and particularly relates to a four-phase highly robust oscillator for high-speed radio frequency communication. Background Art

[0002] With the continuous development of fields such as communication, radar, and high-speed serial transceivers, the requirements for frequency synthesizers are getting higher and higher. Low-noise oscillators are crucial in modern communication systems. Especially in radio frequency communication applications, as one of the core modules of the frequency synthesizer, the noise performance of the oscillator limits the jitter performance of the entire system.

[0003] Oscillators based on inductance and capacitance can obtain superior jitter performance due to the existence of resonant cavities. However, the common parallel LC oscillator structure is difficult to meet the ultra-strict phase noise requirements. In order to meet the requirements of communication standards for jitter performance in wireless communication, radar systems, and high-speed data transmission, new series LC oscillator structures have been widely studied. Oscillators using series resonant cavities can obtain excellent noise performance due to their large amplitudes exceeding the power supply voltage limit. However, the large voltage swing of the series LC oscillator leads to relatively large reliability problems. Summary of the Invention

[0004] In order to solve the above problems existing in the prior art, the present invention provides a four-phase highly robust oscillator for high-speed radio frequency communication. The technical problems to be solved by the present invention are realized through the following technical solutions:

[0005] The present invention provides a four-phase highly robust oscillator for high-speed radio frequency communication, including: two sub-circuits with the same structure;

[0006] Each of the sub-circuits includes: a switched-capacitor array and two resonant units with the same structure;

[0007] The input end of each resonant unit in one sub-circuit is connected to the output ends of the two resonant units in the other sub-circuit;

[0008] The adjustment ends of the two resonant units in one sub-circuit are respectively connected to both ends of the switched-capacitor array in this sub-circuit;

[0009] Each of the resonant units includes: a protection capacitor sub-unit, an amplitude adjustment sub-unit, an active core sub-unit, and a series resonant cavity sub-unit; wherein,

[0010] The input end of the protection capacitor sub-unit is used as the input end of the resonant unit;

[0011] The drain terminal of the active core sub-unit inputs an AC signal, the control terminal is connected to the output terminal of the protection capacitor sub-unit, one end of the amplitude adjustment sub-unit, and the bias voltage, the source terminal is grounded, and the output terminal is connected to the first end of the series resonance cavity sub-unit; the amplitude adjustment sub-unit and the bias voltage are used to reduce the input voltage amplitude of the control terminal of the active core sub-unit;

[0012] The second end of the series resonance cavity sub-unit serves as the output terminal of the resonance unit, and the third end of the series resonance cavity sub-unit serves as the adjustment terminal of the resonance unit.

[0013] Compared with the prior art, the beneficial effects of the present invention are:

[0014] The four-phase highly robust oscillator for high-speed RF communication provided by the present invention reduces the input voltage amplitude of the control terminal of the active core sub-unit through the amplitude adjustment sub-unit and the bias voltage, so that the voltage differences at all terminals of the active device in the active core sub-unit are lower than the power supply voltage, and the large voltage amplitude is controlled inside the passive device (series resonance cavity sub-unit). While achieving low phase noise, its reliability is greatly improved, and it can provide low-noise frequency generation for frequency synthesizers such as phase-locked loops, meeting the requirements of communication standards for jitter performance in wireless communication, radar systems, and high-speed data transmission. Description of the Drawings

[0015] Figure 1 is a schematic structural diagram of a four-phase highly robust oscillator for high-speed RF communication provided by an embodiment of the present invention;

[0016] Figure 2 is an orthogonal output waveform diagram of a four-phase highly robust oscillator for high-speed RF communication provided by an embodiment of the present invention;

[0017] Figure 3 is a schematic structural diagram of a coarse-tuning capacitor array branch provided by an embodiment of the present invention;

[0018] Figure 4 is a schematic structural diagram of a variable capacitor branch provided by an embodiment of the present invention;

[0019] Figure 5 is an inductor layout diagram provided by an embodiment of the present invention;

[0020] Figure 6 is a voltage waveform diagram of each terminal of transistor M1 provided by an embodiment of the present invention;

[0021] Figure 7 is a voltage waveform diagram of each terminal of transistor M2 provided by an embodiment of the present invention;

[0022] Figure 8It is the output phase noise curve of the four-phase highly robust oscillator for high-speed RF communication provided by the embodiments of the present invention;

[0023] Figure 9 It is the voltage waveform diagram of the inductor node provided by the embodiments of the present invention. Detailed implementation manners

[0024] The present invention will be further described in detail below in conjunction with specific embodiments, but the implementation manners of the present invention are not limited thereto.

[0025] Embodiment 1

[0026] Please refer to Figure 1 , Figure 1 It is the structural schematic diagram of the four-phase highly robust oscillator for high-speed RF communication provided by the embodiments of the present invention.

[0027] The four-phase highly robust oscillator for high-speed RF communication provided by the embodiments of the present invention includes: two sub-circuits with the same structure. Each sub-circuit includes: a switched capacitor array and two resonant units with the same structure. The input ends of each resonant unit in one sub-circuit are respectively connected to the output ends of the two resonant units in the other sub-circuit, and the adjustment ends of the two resonant units in one sub-circuit are respectively connected to both ends of the switched capacitor array in this sub-circuit. The phase difference between the output voltages of any one resonant unit in one sub-circuit and any one resonant unit in the other sub-circuit is 90 degrees.

[0028] In this embodiment, the two sub-circuits with the same structure include: a first sub-circuit and a second sub-circuit. The first sub-circuit includes: a first switched capacitor array, a first resonant unit, and a second resonant unit. The second sub-circuit includes: a second switched capacitor array, a third resonant unit, and a fourth resonant unit. The output end of the first resonant unit is connected to the first input end of the third resonant unit and the second input end of the fourth resonant unit. The output end of the second resonant unit is connected to the second input end of the third resonant unit and the first input end of the fourth resonant unit. The adjustment ends of the first resonant unit and the second resonant unit are connected to both ends of the first switched capacitor array. The output end of the third resonant unit is connected to the second input end of the first resonant unit and the first input end of the second resonant unit. The output end of the fourth resonant unit is connected to the first input end of the first resonant unit and the second input end of the second resonant unit. The adjustment ends of the third resonant unit and the fourth resonant unit are connected to both ends of the second switched capacitor array. The phase of the output voltage of the first resonant unit is 90 degrees, the phase of the output voltage of the second resonant unit is 270 degrees, the phase of the output voltage of the third resonant unit is 180 degrees, and the phase of the output voltage of the fourth resonant unit is 0 degrees.

[0029] Specifically, each resonant unit includes: a protection capacitor sub-unit, an amplitude adjustment sub-unit, an active core sub-unit, and a series resonant cavity sub-unit. Among them, the input end of the protection capacitor sub-unit serves as the input end of the resonant unit. An AC signal is input to the drain end of the active core sub-unit. The control end of the active core sub-unit is connected to the output end of the protection capacitor sub-unit, one end of the amplitude adjustment sub-unit, and the bias voltage. The source end of the active core sub-unit is grounded. The output end of the active core sub-unit is connected to the first end of the series resonant cavity sub-unit. The second end of the series resonant cavity sub-unit serves as the output end of the resonant unit, and the third end of the series resonant cavity sub-unit serves as the adjustment end of the resonant unit. Among them, the protection capacitor sub-unit is used to isolate the DC voltage without affecting the AC oscillation voltage, and attenuate the high voltage amplitude, playing a certain protective role for the active core sub-unit to prevent the high voltage from breaking down the transistor of the active core sub-unit. The active core sub-unit is used to provide energy loss compensation for the series resonant cavity sub-unit and achieve an inverting output. The series resonant cavity sub-unit is used to transmit the oscillation voltage output by the active core sub-unit to the next-stage resonant unit through magnetic coupling. The first switched capacitor array and the second switched capacitor array achieve tuning through switched capacitor technology. The amplitude adjustment sub-unit and the bias voltage are used to reduce the input voltage amplitude at the control end of the active core sub-unit to improve the reliability of the oscillator.

[0030] In this embodiment, the protection capacitor sub-unit includes two protection capacitors. The positive electrodes of the two protection capacitors serve as the first input end and the second input end of the protection capacitor sub-unit respectively, and the negative electrodes of the two protection capacitors serve as the first output end and the second output end of the protection capacitor sub-unit respectively. The capacitance values of the two protection capacitors are the same.

[0031] Specifically, the oscillator circuit in this embodiment is a cascade of four series resonant cavity sub-units. The oscillation voltage of the previous stage is transmitted to the next stage through magnetic coupling of the series resonant cavity sub-unit. However, the voltage amplitude after mutual inductance will be relatively large, and there are reliability problems when directly connected to the transistor of the active core sub-unit. High voltage may break down the transistor of the active core sub-unit, causing permanent damage to the transistor. Therefore, the adjacent two stages are coupled to the next-stage circuit through the protection capacitor sub-unit. The capacitor of this protection capacitor sub-unit can isolate the DC voltage without affecting the AC oscillation voltage. At the same time, the capacitor can attenuate the high voltage amplitude, playing a certain protective role to prevent the high voltage from breaking down the transistor.

[0032] Specifically, the amplitude adjustment sub-unit includes: a ground capacitor. The active core sub-unit includes: a first transistor, a second transistor, a first resistor, and a second resistor. The drain of the first transistor inputs an AC signal and is connected to one end of the first resistor. The gate of the first transistor is connected to the first output terminal of the protection capacitor sub-unit, the positive electrode of the ground capacitor, and the other end of the first resistor. The source of the first transistor is connected to the drain of the second transistor. The negative electrode of the ground capacitor is grounded. The gate of the second transistor is connected to the second output terminal of the protection capacitor sub-unit and one end of the second resistor. The source of the first transistor is grounded. The other end of the second resistor is connected to a bias voltage. Both the first transistor and the second transistor are deep N-well NMOS.

[0033] Furthermore, the active core sub-unit is used to provide energy loss compensation for the series resonant cavity sub-unit. Among them, the first transistor operates in a source follower mode and acts as a voltage buffer. The gate of the first transistor is biased at VDD, receives the oscillation voltage signal of the previous stage at the gate, and drives the series resonant cavity at the source, so that the source potential can oscillate in phase following the gate voltage. The second transistor operates as a common source amplifier and outputs in anti-phase at the drain. The N-N inverter composed of two NMOSs jointly forms a negative resistance that provides energy loss compensation for the series resonant cavity. The output jointly drives the series resonant cavity. The impedance of the series resonant cavity is the lowest at the resonance point, and the series resonant cavity presents a pure resistance. At frequencies higher than the resonance frequency, the series resonant cavity becomes inductive. The closer the oscillator is to the resonance frequency, the greater its current. The output of the active core sub-unit is connected to the next stage after mutual inductance through the series resonant cavity, and is input to the active core of the next stage after being coupled by the protection capacitor of the next stage. Each time it passes through one stage, the phase shifts by 90 degrees, and 4-phase orthogonal output can be achieved. The orthogonal output waveform is as Figure 2 shown, Figure 2 where D1, D2, D3, and D4 in Figure 1 represent the signals sampled from the nodes D1, D2, D3, and D4 in

[0034] Specifically, the series resonant cavity sub-unit includes: a resonant inductor, a resonant capacitor, and a transformer inductor; one end of the resonant inductor is connected to the drain of the second transistor, the other end of the resonant inductor is connected to the negative electrode of the resonant capacitor, and the positive electrode of the resonant capacitor is grounded; the transformer inductor and the resonant inductor have mutual inductance. One end of the transformer inductor serves as the first output terminal of the series resonant cavity sub-unit, and the other end of the transformer inductor serves as the second output terminal of the series resonant cavity sub-unit.

[0035] In this embodiment, as Figure 1 shown, Figure 1The left half of the circuit is the first sub-circuit, and the right half of the circuit is the first sub-circuit. The upper half of the first sub-circuit is the first resonant unit, and the lower half is the second resonant unit. The adjustment terminals of the first resonant unit and the second resonant unit are connected to the first switched-capacitor array. The upper half of the second sub-circuit is the third resonant unit, and the lower half is the fourth resonant unit. The adjustment terminals of the third resonant unit and the fourth resonant unit are connected to the second switched-capacitor array. Taking the first resonant unit as an example, the first resonant unit includes: a first protection capacitor sub-unit, a first amplitude adjustment sub-unit, a first active core sub-unit, and a first series resonant cavity sub-unit. Among them, the first protection capacitor sub-unit includes: protection capacitor C1 and protection capacitor C2, the first amplitude adjustment sub-unit includes a grounded capacitor C3, the first active core sub-unit includes: transistor M1, transistor M2, resistor R1, and resistor R2, and the first series resonant cavity sub-unit includes: resonant inductor L1, resonant capacitor C15, and transformer inductor L3. That is, the first resonant unit includes: protection capacitor C1, protection capacitor C2, grounded capacitor C3, transistor M1, transistor M2, resistor R1, resistor R2, resonant inductor L1, resonant capacitor C15, and transformer inductor L3. The specific connection relationship is: the positive electrode of protection capacitor C1 is the first input terminal of the first resonant unit, the negative electrode of protection capacitor C1 is connected to the positive electrode of grounded capacitor C3, the gate of transistor M1, and one end of resistor R1. The other end of resistor R1 is connected to the drain of transistor M1 and inputs an AC signal. The positive electrode of protection capacitor C2 is the second input terminal of the first resonant unit, the negative electrode of protection capacitor C2 is connected to the gate of transistor M2 and one end of resistor R2, and the other end of resistor R2 inputs a bias voltage Vbias. The negative electrode of grounded capacitor C3 and the source of transistor M2 are both grounded. The source of transistor M1 and the drain of transistor M2 are connected and used as the output terminal of the first active core sub-unit to connect to one end of resonant inductor L1. Resonant inductor L1 and transformer inductor L3 are mutually inductive. The other end of resonant inductor L1 is connected to the negative electrode of resonant capacitor C15, the positive electrode of resonant capacitor C15 is grounded, one end of transformer inductor L3 is used as the output terminal of the first resonant unit, and the other end of transformer inductor L3 is used as the adjustment terminal of the first resonant unit.

[0036] Further, the second resonant unit includes: a protection capacitor C4, a protection capacitor C5, a ground capacitor C6, a second active core sub-unit, a resonant inductor L2, a resonant capacitor C16, and a transformer inductor L4. The third resonant unit includes: a protection capacitor C7, a protection capacitor C8, a ground capacitor C9, a third active core sub-unit, a resonant inductor L5, a resonant capacitor C17, and a transformer inductor L7. The fourth resonant unit includes: a protection capacitor C10, a protection capacitor C11, a ground capacitor C12, a fourth active core sub-unit, a resonant inductor L6, a resonant capacitor C18, and a transformer inductor L8. The internal connection relationships of the second resonant unit, the third resonant unit, and the fourth resonant unit are the same as those of the first resonant unit, which will not be elaborated here. The connection relationships among the first resonant unit, the second resonant unit, the third resonant unit, and the fourth resonant unit are as follows: one end of the transformer inductor L3 is connected to the positive electrodes of the protection capacitor C7 and the protection capacitor C11, and the other end of the transformer inductor L3 is connected to the first connection end of the first switched capacitor array. One end of the transformer inductor L4 is connected to the positive electrodes of the protection capacitor C8 and the protection capacitor C10, and the other end of the transformer inductor L4 is connected to the second connection end of the first switched capacitor array. One end of the transformer inductor L7 is connected to the positive electrodes of the protection capacitor C2 and the protection capacitor C4, and the other end of the transformer inductor L4 is connected to the first connection end of the second switched capacitor array. One end of the transformer inductor L8 is connected to the positive electrodes of the protection capacitor C1 and the protection capacitor C5, and the other end of the transformer inductor L8 is connected to the second connection end of the second switched capacitor array.

[0037] Please refer to Figure 3 and Figure 4 , in this embodiment, the first switched capacitor array and the second switched capacitor array have the same structure, both including: a coarse-tuning capacitor array branch and a variable capacitor branch connected in parallel. Taking the first switched capacitor array as an example for illustration, the coarse-tuning capacitor array branch in the first switched capacitor array includes: a first coarse-tuning capacitor C13, a second coarse-tuning capacitor C14, a first coarse-tuning transistor M3, a second coarse-tuning transistor M4, a third coarse-tuning transistor M5, a fourth coarse-tuning transistor M6, and a fifth coarse-tuning transistor M7. Among them, the negative electrode of the first coarse-tuning capacitor C13 serves as the first connection end V P of the coarse-tuning capacitor array branch, and the positive electrode of the first coarse-tuning capacitor C13 is connected to the source electrode of the first coarse-tuning transistor M3, the drain electrode of the third coarse-tuning transistor M5, and the source electrode of the fifth coarse-tuning transistor M7. The negative electrode of the second coarse-tuning capacitor C14 serves as the second connection end V N, the positive electrode of the second coarse-tuning capacitor C14 is connected to the source electrode of the second coarse-tuning transistor M4, the drain electrode of the fourth coarse-tuning transistor M6, and the drain electrode of the fifth coarse-tuning transistor M7. The gate electrodes of the first coarse-tuning transistor M3 and the second coarse-tuning transistor M4 are connected, and the drain electrodes of the first coarse-tuning transistor M3 and the second coarse-tuning transistor M4 are connected. The gate electrodes of the third coarse-tuning transistor M5, the fourth coarse-tuning transistor M6, and the fifth coarse-tuning transistor M7 are connected, and the source electrodes of the third coarse-tuning transistor M5 and the fourth coarse-tuning transistor M6 are connected. The drain electrodes of the first coarse-tuning transistor M3 and the second coarse-tuning transistor M4 are connected to the power supply voltage VDD, and the source electrodes of the third coarse-tuning transistor M5 and the fourth coarse-tuning transistor M6 are grounded.

[0038] In this embodiment, the coarse-tuning capacitor array branch is a 5-bit switched capacitor array, the frequency tuning range is 14.13G - 15.1GHz, and continuous frequency modulation is realized by using variable capacitors. Figure 3 The upper part is the equivalent circuit diagram of the coarse-tuning capacitor array branch in the open state, and the lower part is the equivalent circuit diagram of the coarse-tuning capacitor array branch in the closed state.

[0039] Specifically, the variable capacitor branch in the first switched capacitor array includes: a first variable capacitor VC1, a second variable capacitor VC2, a first fine-tuning resistor R3, and a second fine-tuning resistor R4. The negative electrodes of the first variable capacitor VC1 and the second variable capacitor VC2 are connected, the positive electrode of the first variable capacitor VC1, one end of the first fine-tuning resistor R3, and the first connection end V of the coarse-tuning capacitor array branch P are connected, the positive electrode of the second variable capacitor VC2, one end of the second fine-tuning resistor R4, and the second connection end V of the coarse-tuning capacitor array branch N are connected, and the other ends of the first fine-tuning resistor R3 and the second fine-tuning resistor R4 are connected. The first connection end V P is connected to the other end of the transformer inductance L3, and the second connection end V N is connected to the other end of the transformer inductance L4. The variable capacitor branch can generate a large capacitance change according to the change of the control voltage for realizing capacitance fine-tuning, and the coarse-tuning capacitor array branch is used for realizing capacitance coarse-tuning.

[0040] Please refer to Figure 5 , Figure 5It is the inductor layout diagram provided by the embodiment of the present invention. Since there are four inductors in a sub-circuit of the oscillator provided in this embodiment, in order to reduce the area and improve the integration degree, the four inductors are folded into two cores. Taking the resonant inductor L1, resonant inductor L2, transformer inductor L3 and transformer inductor L4 as examples for illustration, the resonant inductors L1 and L2 have the main coils on the periphery, one end of which is connected to the output of the active core sub-unit, and the other end is grounded through a capacitor to form a series resonant cavity. The transformer inductors L3 and L4 are nested inside as secondary coils, surrounding the entire coil. They have a relatively large inductance. One end of them is connected to the input of the next-level active core sub-unit, and the other end is connected to the switched capacitor array for frequency tuning. The mutual inductance coefficient between the main coil L1 (or L2) and the secondary coil L3 (or L4) is about 0.35. The mutual inductance coefficient between the two middle secondary coils is at most about 0.59. At the same time, there is also a mutual inductance coefficient between the main coil L1 (or L2) and the other secondary coil L4 (or L3), which is 0.25. There is also mutual inductance between the resonant inductors L1 and L2. Since they are far apart, the mutual inductance coefficient is the smallest, which is 0.165.

[0041] The oscillator circuit provided in this embodiment adopts the 65nm CMOS process and the power supply voltage is 1.2V. For MOS transistors, the gate-source voltage (VGS), drain-source voltage (VDS), gate-drain voltage (VDG) and the voltage between the substrate should all be lower than 1.2V. If they exceed this limit, the MOS transistors will suffer from "stress", which will affect the service life. In order to improve the reliability and avoid the influence of the large voltage of the series resonance on the life of the active device, in this embodiment, a grounded capacitor is used to divide the input voltage of the control terminal of the active core sub-unit, and the input voltage of the control terminal of the active core sub-unit is controlled through the bias voltage to improve its reliability.

[0042] Specifically, taking the first active core sub-unit as an example for illustration, for the transistor M1 that works in the source follower mode, its drain is connected to the 1.2V power supply voltage, and a grounded capacitor to the ground is added to its gate. This capacitor and the protection capacitor sub-unit together constitute the voltage division of the AC signal to reduce its amplitude. At the same time, the grounded capacitor does not contribute noise and its phase noise performance does not deteriorate. The voltage waveforms at each end of the transistor M1 are as Figure 6, the blue curve is the voltage at the mutual inductance of the secondary coil of the transformer (node V0). Its oscillating voltage ranges from -3V to 3.8V, with a large amplitude of 3.4V. After capacitor voltage division (node A1), it becomes the yellow curve, changing from 0.35V to 1.85V, and the voltage difference from the drain voltage is less than 1.2V. The red curve is the output of the N-N inverter (node D1). Due to the switching action, its output voltage waveform is approximately square-wave, oscillating from about 0.1V to 1V, and the voltage difference from the drain voltage is also less than 1.2V. Since this transistor operates in the source follower mode, the source output voltage follows the gate voltage and fluctuates synchronously, and the maximum voltage difference of VGS does not exceed 1V. The transistor M2 operating in the common source stage mode has a 180° phase difference between the drain output voltage and the gate voltage, with an inverse oscillation. It is easy to have overvoltage between the high voltage amplitude received by the gate and the transient oscillating voltage output by the drain. Therefore, in this embodiment, the gate of the transistor M2 is biased at a low voltage by a bias voltage. This bias voltage should ensure that the transistor M2 is turned on while maintaining the DC operating point of the oscillating voltage at a relatively low level to ensure no overvoltage. Figure 7 are the voltage waveforms at each terminal of the transistor M2. The voltage at node V180 is the voltage after the mutual inductance of the secondary coil of the transformer. This voltage has a 180° phase difference from the voltage received by the gate of the transistor M2. Its oscillating voltage ranges from -3V to 3.8V. After capacitor attenuation, if it is also biased at the power supply voltage of 1.2V, it is easy to have overvoltage at the upper half cycle and the low point of the output waveform. The bias voltage biases the gate of the transistor M2 at 0.6V, shifting its waveform downward as a whole. The attenuated gate voltage waveform is as shown by the blue curve (node B1), oscillating from about -0.1V to 1.2V, and VGD is around 1.1V. Both the gate and drain voltages operate below the power supply voltage of 1.2V, and neither VGS nor VDS has overvoltage.

[0043] The oscillator provided by this embodiment can achieve frequency generation with extremely low phase noise. The phase noise curve of the oscillator output is as Figure 8 shown. When the output frequency is 14.13GHz, the oscillator output phase noise is -130.75dBc / Hz@1MHz. When the output frequency is 15.1GHz, the oscillator output phase noise is -126dBc / Hz@1MHz. This embodiment improves the phase noise performance by increasing the amplitude at the series resonance point to break through the limitation of the power supply voltage, similar to class D oscillators. Figure 9 is the voltage waveform at the inductor node (node E2). The FoM of the oscillator provided by this embodiment is as shown in the following table:

[0044]

[0045] This embodiment provides a four-phase highly robust oscillator for high-speed radio frequency communication. By means of an amplitude adjustment subunit and a bias voltage, the input voltage amplitude at the control end of the active core subunit is reduced, so that the voltage differences at all ends of the active devices in the active core subunit are lower than the power supply voltage, and the large voltage amplitude is controlled inside the passive devices (series resonator subunit). While achieving low phase noise, its reliability is greatly improved, and it can provide low-noise frequency generation for frequency synthesizers such as phase-locked loops, meeting the requirements of communication standards for jitter performance in wireless communication, radar systems, and high-speed data transmission.

[0046] The above content is a further detailed description of the present invention in combination with specific preferred embodiments, and it cannot be determined that the specific implementation of the present invention is only limited to these descriptions. For those of ordinary skill in the technical field to which the present invention belongs, without departing from the concept of the present invention, several simple deductions or substitutions can be made, and all should be regarded as belonging to the protection scope of the present invention.

Claims

1. A four-phase highly robust oscillator for high-speed radio frequency communications, characterized in that: include: Two subcircuits with identical structure; Each of the sub-circuits comprises: a switched capacitor array and two resonant units with the same structure; The input end of each resonant unit in one subcircuit is connected to the output ends of two resonant units in another subcircuit; The adjustment ends of the two resonant units in one subcircuit are respectively connected to the two ends of the switch capacitor array in the subcircuit; Each of the resonance units comprises: a protection capacitor subunit, an amplitude adjustment subunit, an active core subunit, and a series resonance cavity subunit; wherein, The input end of the protection capacitor subunit serves as the input end of the resonance unit; The drain end of the active core subunit inputs an AC signal, the control end is connected to the output end of the protection capacitor subunit, one end of the amplitude adjustment subunit and the bias voltage, the source end is grounded, and the output end is connected to the first end of the series resonant cavity subunit; the amplitude adjustment subunit and the bias voltage are used to reduce the input voltage amplitude of the control end of the active core subunit; The second end of the series resonant cavity subunit serves as the output end of the resonant unit, and the third end of the series resonant cavity subunit serves as the regulating end of the resonant unit.

2. The four-phase high-robustness oscillator for high-speed radio frequency communication according to claim 1, characterized in that: The protection capacitor subunit includes two protection capacitors; The positive electrodes of the two protection capacitors serve as the first input terminal and the second input terminal of the protection capacitor subunit respectively; The negative electrodes of the two protection capacitors serve as the first output terminal and the second output terminal of the protection capacitor subunit respectively.

3. The four-phase high-robustness oscillator for high-speed radio frequency communication according to claim 2, characterized in that: The two protection capacitors have the same capacitance.

4. The four-phase high-robustness oscillator for high-speed radio frequency communication according to claim 2, characterized in that: The amplitude adjustment subunit includes: a capacitor to ground; The active core subunit includes: a first transistor, a second transistor, a first resistor and a second resistor; The drain of the first transistor inputs an AC signal and is connected to one end of the first resistor, the gate of the first transistor is connected to the first output end of the protection capacitor subunit, the positive electrode of the ground capacitor and the other end of the first resistor, the source of the first transistor is connected to the drain of the second transistor; the negative electrode of the ground capacitor is grounded; The gate of the second transistor is connected to the second output end of the protection capacitor subunit and one end of the second resistor, the source of the first transistor is grounded; and the other end of the second resistor is connected to the bias voltage.

5. The four-phase high-robustness oscillator for high-speed radio frequency communication according to claim 4, characterized in that: The series resonant cavity subunit includes: a resonant inductor, a resonant capacitor and a transformer inductor; One end of the resonant inductor is connected to the drain of the second transistor, the other end of the resonant inductor is connected to the negative electrode of the resonant capacitor, and the positive electrode of the resonant capacitor is grounded; The transformer inductor and the resonant inductor are mutually inductive, one end of the transformer inductor serves as the first output end of the series resonant cavity subunit, and the other end of the transformer inductor serves as the second output end of the series resonant cavity subunit.

6. The four-phase high-robustness oscillator for high-speed radio frequency communication according to claim 4, characterized in that: The first transistor and the second transistor are both deep N-well NMOS.

7. The four-phase high-robustness oscillator for high-speed radio frequency communication according to claim 1, characterized in that: The switch capacitor array comprises: a coarse adjustment capacitor array branch and a variable capacitor branch connected in parallel; The coarse tuning capacitor array branch includes: a first coarse tuning capacitor, a second coarse tuning capacitor, a first coarse tuning transistor, a second coarse tuning transistor, a third coarse tuning transistor, a fourth coarse tuning transistor and a fifth coarse tuning transistor, wherein: The negative electrode of the first coarse adjustment capacitor serves as the first connection end of the coarse adjustment capacitor array branch, and the positive electrode of the first coarse adjustment capacitor is connected to the source of the first coarse adjustment transistor, the drain of the third coarse adjustment transistor and the source of the fifth coarse adjustment transistor; The negative electrode of the second coarse adjustment capacitor serves as the second connection end of the coarse adjustment capacitor array branch, and the positive electrode of the second coarse adjustment capacitor is connected to the source of the second coarse adjustment transistor, the drain of the fourth coarse adjustment transistor and the drain of the fifth coarse adjustment transistor; The gate of the first coarse adjustment transistor is connected to the gate of the second coarse adjustment transistor, and the drain of the first coarse adjustment transistor is connected to the drain of the second coarse adjustment transistor; The gate of the third coarse adjustment transistor, the gate of the fourth coarse adjustment transistor and the gate of the fifth coarse adjustment transistor are connected, and the source of the third coarse adjustment transistor and the source of the fourth coarse adjustment transistor are connected.

8. The four-phase high-robustness oscillator for high-speed radio frequency communication according to claim 7, characterized in that: The variable capacitor branch includes: a first variable capacitor, a second variable capacitor, a first fine-tuning resistor and a second fine-tuning resistor; The negative electrode of the first variable capacitor is connected to the negative electrode of the second variable capacitor, the positive electrode of the first variable capacitor, one end of the first fine-tuning resistor and the first connection end of the coarse-tuning capacitor array branch are connected, the positive electrode of the second variable capacitor, one end of the second fine-tuning resistor and the second connection end of the coarse-tuning capacitor array branch are connected, and the other end of the first fine-tuning resistor is connected to the other end of the second fine-tuning resistor.

9. The four-phase high-robustness oscillator for high-speed radio frequency communication according to claim 1, characterized in that: The phase difference between the output voltages of any resonance unit in one sub-circuit and any resonance unit in another sub-circuit is 90 degrees.

10. The four-phase high-robustness oscillator for high-speed radio frequency communication according to claim 9, characterized in that: The two sub-circuits with the same structure include: a first sub-circuit and a second sub-circuit; The first sub-circuit includes: a first switched capacitor array, a first resonant unit and a second resonant unit; The second sub-circuit includes: a second switched capacitor array, a third resonant unit and a fourth resonant unit; The output end of the first resonance unit is connected to the first input end of the third resonance unit and the second input end of the fourth resonance unit; The output end of the second resonance unit is connected to the second input end of the third resonance unit and the first input end of the fourth resonance unit; The regulating end of the first resonance unit and the regulating end of the second resonance unit are connected to two ends of the first switch capacitor array; The output end of the third resonance unit is connected to the second input end of the first resonance unit and the first input end of the second resonance unit; The output end of the fourth resonance unit is connected to the first input end of the first resonance unit and the second input end of the second resonance unit; The adjustment end of the third resonance unit and the adjustment end of the fourth resonance unit are connected to two ends of the second switch capacitor array; The phase of the output voltage of the first resonance unit is 90 degrees, the phase of the output voltage of the second resonance unit is 270 degrees, the phase of the output voltage of the third resonance unit is 180 degrees, and the phase of the output voltage of the fourth resonance unit is 0 degree.

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