A low phase noise meandered ring oscillator

Abstract

The application discloses a low phase noise kinked ring oscillator, and belongs to the technical field of integrated circuits.The kinked ring oscillator comprises three five-stage ring oscillator cores connected in parallel;the three ring oscillator cores are tightly interconnected in a cross feedback mode through a coupler to form a unique "kinked" topological structure.The structure utilizes mutual coupling and average effect of the multi-core signals to effectively suppress phase noise of a single path, realizes low-power operation, enhances robustness of the circuit to process deviation, and significantly reduces phase noise under the premise of maintaining low power consumption and small area.The application has compact structure and is suitable for integrated circuit systems with high clock quality requirement.

Description

Technical Field

[0001] This invention belongs to the field of integrated circuit technology, and specifically relates to a low phase noise kink ring oscillator. Background Technology

[0002] The ring oscillator is a core circuit module in a System-on-a-Chip (SoC) that generates clock signals. Traditional single-core ring oscillators have a theoretical limit to their phase noise performance; their phase noise power spectral density is inversely proportional to the number of cores. In applications such as high-speed serial interfaces and RF front-ends, the requirements for clock signal purity (low phase noise) and power consumption are extremely stringent.

[0003] Existing ring oscillators improve phase noise by increasing the number of stages or raising the power supply voltage, but this directly leads to increased chip area and significantly increased power consumption, making it difficult to meet the energy efficiency and integration requirements of advanced process nodes. Furthermore, inter-core mismatch caused by process variations will further deteriorate the oscillator's performance consistency.

[0004] Therefore, how to significantly reduce phase noise while maintaining low power consumption and small area is a technical challenge that urgently needs to be solved in this field. Summary of the Invention

[0005] To address the aforementioned problems in the prior art, this invention provides a low-phase-noise kinked ring oscillator. The technical problem to be solved by this invention is achieved through the following technical solution:

[0006] This invention provides a low-phase-noise kink-type ring oscillator, comprising:

[0007] The first ring oscillator core, the second ring oscillator core, and the third ring oscillator core are connected in parallel; among them,

[0008] The three ring oscillator cores are tightly interconnected in a cross-feedback manner through couplers in the first, second, and third ring oscillator cores to form a corresponding kink-type topology. Through the mutual modulation of signals between the cores, noise averaging is achieved and phase noise is suppressed.

[0009] The beneficial effects of this invention are:

[0010] The solution provided in this invention utilizes a coupler to form a kink-type topology. This structure effectively suppresses single-path phase noise by leveraging the mutual coupling and averaging effect of multi-core signals, achieving excellent phase noise performance of -95 to -100 dBc / Hz at 500 MHz. While achieving high performance, the overall power consumption is controlled to 5 mW, demonstrating significant energy efficiency. The kink-type topology designed in this invention enhances the circuit's tolerance to variations in process technology, voltage, and temperature, reducing mismatch. Attached Figure Description

[0011] Figure 1 This is a schematic diagram of a low-phase-noise kink-type ring oscillator provided in an embodiment of the present invention;

[0012] Figure 2 This is a schematic diagram of the coupler structure in a low-phase-noise kink-type ring oscillator provided in an embodiment of the present invention;

[0013] Figure 3 This is a schematic diagram of the inverter structure in a low-phase-noise kinked ring oscillator provided in an embodiment of the present invention;

[0014] Figure 4 The simulation diagram of phase noise corresponding to a low phase noise kink ring oscillator provided in the embodiment of the present invention. Detailed Implementation

[0015] The present invention will be further described in detail below with reference to specific embodiments, but the implementation of the present invention is not limited thereto.

[0016] To reduce oscillator phase noise and power consumption, embodiments of the present invention provide a low-phase-noise kinked ring oscillator, such as... Figure 1 As shown, it may include:

[0017] The first ring oscillator core, the second ring oscillator core, and the third ring oscillator core are connected in parallel; among them,

[0018] The three ring oscillator cores are tightly interconnected in a cross-feedback manner through couplers in the first, second, and third ring oscillator cores to form a corresponding kink-type topology. Through the mutual modulation of signals between the cores, noise averaging is achieved and phase noise is suppressed.

[0019] The low-phase-noise kinked ring oscillator provided in this invention tightly interconnects three ring oscillator cores via couplers in a cross-feedback manner, forming a unique kinked topology. This kinked topology effectively suppresses single-path phase noise by utilizing the mutual coupling and averaging effect of signals between cores, while achieving low-power operation and enhancing the circuit's robustness to process variations. This low-phase-noise kinked ring oscillator has a compact structure and is suitable for integrated circuit systems with high clock quality requirements.

[0020] In a low-phase-noise kink ring oscillator, the input signal IN2 of the second ring oscillator core is output as out1 signal through the third inverter INV3.

[0021] The input signal IN1 of the first ring oscillator core is output as out2 signal after passing through the first inverter INV1, the first coupler C1 and the fourth inverter INV4.

[0022] The input signal IN3 of the third ring oscillator core is output as out3 signal through the seventh inverter INV7, the fifth coupler C5, the second inverter INV2, the second coupler C2, and the ninth inverter INV9.

[0023] The first ring oscillator core, such as Figure 1 As shown, it may include:

[0024] The system comprises a first coupler C1, a third coupler C3, a first inverter INV1, a fourth inverter INV4, and a fifth inverter INV5; among which...

[0025] The input terminal of the first inverter INV1 is connected to the input signal IN1 and is connected to the output terminal of the third coupler C3. The output terminal is connected to the first input terminal of the first coupler C1.

[0026] The second input terminal of the first coupler C1 serves as the first coupling terminal of the first ring oscillator core, and its output terminal is connected to the input terminal of the fourth inverter INV4.

[0027] The output terminal of the fourth inverter INV4 is connected to the input terminal of the fifth inverter INV5, the first coupling terminal of the second ring oscillator core, and the second coupling terminal of the third ring oscillator core, respectively.

[0028] The output of the fifth inverter INV5 is connected to the first input of the third coupler C3;

[0029] The second input terminal of the third coupler C3 serves as the second coupling terminal of the first ring oscillator core, and the output terminal serves as the output terminal of the first ring oscillator core.

[0030] In the first ring oscillator core, the input signal IN1 is output to the first input terminal of the first coupler C1 through the first inverter INV1, and coupled with the signal received at the second input terminal of the first coupler C1. The coupled signal is input to the fourth inverter INV4, and then input to the first input terminal of the third coupler C3 through the fifth inverter INV5, and coupled with the signal received at the second input terminal of the third coupler C3. The coupled signal is then fed back to the input terminal of the first inverter INV1 to form the closed-loop oscillation path of the first ring oscillator core.

[0031] Understandably, the signal received at the second input terminal of the first coupler C1 is the out1 signal, and the signal received at the second input terminal of the third coupler C3 is the out3 signal. Through the coupling of the first coupler C1 and the third coupler C3 in this closed-loop oscillation path, the first ring oscillator core is modulated by the signals corresponding to the second and third ring oscillator cores, reducing phase noise and mismatch.

[0032] The second ring oscillator core, such as Figure 1 As shown, it may include:

[0033] The fourth coupler C4, the sixth coupler C6, the third inverter INV3, the sixth inverter INV6, and the eighth inverter INV8; among them,

[0034] The input terminal of the third inverter INV3 is connected to the input signal IN2 and is connected to the output terminal of the fourth coupler C4. The output terminal is connected to the first coupling terminal of the first ring oscillator core and the first coupling terminal of the third ring oscillator core, respectively.

[0035] The input terminal of the eighth inverter INV8 is connected to the output terminal of the third inverter INV3, and the output terminal is connected to the second input terminal of the sixth coupler C6.

[0036] The first input terminal of the sixth coupler C6 serves as the first coupling terminal of the second ring oscillator core, and its output terminal is connected to the input terminal of the sixth inverter INV6.

[0037] The output of the sixth inverter INV6 is connected to the first input of the fourth coupler C4;

[0038] The second input terminal of the fourth coupler C4 serves as the second coupling terminal of the second ring oscillator core, and the output terminal serves as the output terminal of the second ring oscillator core.

[0039] In the second ring oscillator core, the input signal IN2 passes through the third inverter INV3 and the eighth inverter INV8, and is input to the second input terminal of the sixth coupler C6. It is coupled with the signal received at the first input terminal of the sixth coupler C6. The coupled signal is then input through the sixth inverter INV6 to the first input terminal of the fourth coupler C4, and is coupled with the signal received at the second input terminal of the fourth coupler C4. The coupled signal is then fed back to the input terminal of the third inverter INV3 to form the closed-loop oscillation path of the second ring oscillator core.

[0040] Understandably, the signal received at the first input terminal of the sixth coupler C6 is the out2 signal, and the signal received at the second input terminal of the fourth coupler C4 is the out3 signal. Through the coupling of the fourth coupler C4 and the sixth coupler C6 in this closed-loop oscillation path, the second ring oscillator core is interconnected with the first ring oscillator core and the third ring oscillator core, thereby enhancing the overall stability.

[0041] The third ring oscillator core, such as Figure 1 As shown, it may include:

[0042] The second coupler C2, the fifth coupler C5, the second inverter INV2, the seventh inverter INV7, and the ninth inverter INV9; among which...

[0043] The input terminal of the seventh inverter INV7 is connected to the input signal IN3 and is connected to the output terminal of the ninth inverter INV9. The output terminal is connected to the second input terminal of the fifth coupler C5.

[0044] The first input terminal of the fifth coupler C5 serves as the first coupling terminal of the third ring oscillator core, and its output terminal is connected to the input terminal of the second inverter INV2.

[0045] The output of the second inverter INV2 is connected to the second input of the second coupler C2;

[0046] The first input terminal of the second coupler C2 serves as the second coupling terminal of the third ring oscillator core, and its output terminal is connected to the input terminal of the ninth inverter INV9.

[0047] The output of the ninth inverter INV9 is connected to the second coupling terminal of the first ring oscillator core and the second coupling terminal of the second ring oscillator core, respectively, and serves as the output terminal of the third ring oscillator core.

[0048] In the third ring oscillator core, the input signal IN3 passes through the seventh inverter INV7 and is input to the second input terminal of the fifth coupler C5, where it is coupled with the signal received at the first input terminal of the fifth coupler C5. The coupled signal then passes through the second inverter INV2 and is input to the second input terminal of the second coupler C2, where it is coupled with the signal received at the first input terminal of the second coupler C2. The coupled signal then passes through the ninth inverter INV9, and the signal output from the ninth inverter INV9 is fed back to the input terminal of the seventh inverter INV7 to form the closed-loop oscillation path of the third ring oscillator core.

[0049] Understandably, the signal received at the first input terminal of the second coupler C2 is the out2 signal, and the signal received at the first input terminal of the fifth coupler C5 is the out1 signal.

[0050] The low-phase-noise kink-type ring oscillator provided in this embodiment of the invention enables the three ring oscillator cores to oscillate synchronously through real-time coupling of inter-core signals, thereby reducing phase noise and mismatch and lowering power consumption.

[0051] All couplers in the first, second, and third ring oscillator cores have the same structure. For example, the couplers... Figure 2 As shown, it may include:

[0052] MOSFETs PM0, PM1, NM0, and NM1; among them,

[0053] The source of MOSFET PM0 is connected to the power supply voltage VDD, and its gate is connected to the gate of MOSFET NM0, serving as the first input terminal of the coupler. Its drain is connected to the source of MOSFET PM1.

[0054] The gate of MOSFET PM1 is connected to the gate of MOSFET NM1, serving as the second input terminal of the coupler, and the drain is connected to the drain of MOSFET NM1, serving as the output terminal of the coupler.

[0055] The source of MOSFET NM0 is grounded, and its drain is connected to the source of MOSFET NM1.

[0056] All inverters in the first, second, and third ring oscillator cores have the same structure. Inverters, such as... Figure 3 As shown, it may include:

[0057] MOSFET PM2 and MOSFET NM2; among them,

[0058] The source of MOSFET PM2 is connected to the power supply voltage VDD, and its gate is connected to the gate of MOSFET NM2, serving as the input terminal of the inverter. Its drain is connected to the drain of MOSFET NM2, serving as the output terminal of the inverter.

[0059] The source of MOSFET NM2 is grounded.

[0060] The kink-type ring oscillator provided by this invention incorporates a coupler to form a kink-type topology. This structure utilizes the mutual coupling and averaging effect of multi-core signals to effectively suppress single-path phase noise, achieving excellent phase noise performance of -95 to -100 dBc / Hz at 500 MHz. While achieving high performance, the kink-type ring oscillator maintains overall power consumption at 5 mW, demonstrating significant energy efficiency. The kink-type topology designed in this invention enhances the circuit's tolerance to variations in process technology, voltage, and temperature, reducing mismatch.

[0061] The following simulation experiment demonstrates the beneficial effects of the kinked ring oscillator based on the embodiments of the present invention:

[0062] The simulation experimental components of this invention can be constructed using SMIC 55nm CMOS technology. Under the Linux system, the simulation circuit of this invention is built based on the Cadence IC617 simulation experimental platform.

[0063] In this embodiment of the invention, the Specture simulation tool is used to simulate the specific circuit. Given a power supply voltage VDD of 1.2V, the oscillator is tested under three different process corner models: TT, SS, and FF. The simulation is conducted within a temperature range of -40 to 125℃.

[0064] Under the above operating conditions, using the Specture simulation tool, with a corresponding output port added to the output end, PSS+PNOISE simulation was performed on the embodiment of the present invention. The simulation results of the phase noise corresponding to the kink-type ring oscillator are as follows: Figure 4 As shown, the horizontal axis represents the offset frequency (Hz), and the vertical axis represents the output signal phase noise (dBc / Hz). From Figure 4 The simulation results of the phase noise show that the phase noise of the embodiment of the present invention is -100dBc / Hz at a 1MHz offset frequency under a 500MHz operating frequency. This kink-type ring oscillator achieves a phase noise of -100dBc / Hz at 500MHz, and consumes only 5mW, which has a significant advantage in energy efficiency compared with traditional technologies.

[0065] Existing cross-coupling technologies mostly employ loose cascaded structures. However, the three five-stage ring oscillator cores designed in this invention are tightly interconnected by six couplers, forming a unique "knot-type" topology in each pair. During ring oscillator signal transmission, every two signals are coupled through the coupler before entering the next stage inverter. The coupler enables bidirectional signal interaction (e.g., the feedback path of the first ring oscillator core is simultaneously modulated by the second and third ring oscillator cores), emphasizing multi-core collaborative noise suppression. The coupling method is complex, and the output consists of three in-phase oscillation signals, reducing phase noise and minimizing mismatch. The structure is more complex, focusing on noise averaging and robustness rather than simple multiphase clock generation. This knot-type ring oscillator coupler deeply integrates the three ring oscillator cores into a unified oscillation system; through inter-core signal modulation (e.g., the coupler C3 of the first ring oscillator core simultaneously receives the out3 signal of the third ring oscillator core), noise averaging is achieved, breaking through the traditional single-ring noise limit.

[0066] It should be noted that, in the description of this invention, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0067] It should also be noted that, unless otherwise explicitly specified and limited, the terms "set up," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0068] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention are included within the scope of protection of the present invention.

Claims

1. A low-phase-noise kinked ring oscillator, characterized in that, include: The first ring oscillator core, the second ring oscillator core, and the third ring oscillator core are connected in parallel; among them, The three ring oscillator cores are tightly interconnected via couplers in the first, second, and third ring oscillator cores using a cross-feedback configuration, forming a corresponding kinked topology. Inter-core signal modulation is used to achieve noise averaging and suppress phase noise. The first ring oscillator core includes: The system comprises a first coupler C1, a third coupler C3, a first inverter INV1, a fourth inverter INV4, and a fifth inverter INV5; among which... The input terminal of the first inverter INV1 is connected to the input signal IN1 and is connected to the output terminal of the third coupler C3. The output terminal is connected to the first input terminal of the first coupler C1. The second input terminal of the first coupler C1 serves as the first coupling terminal of the first ring oscillator core, and its output terminal is connected to the input terminal of the fourth inverter INV4. The output terminal of the fourth inverter INV4 is connected to the input terminal of the fifth inverter INV5, the first coupling terminal of the second ring oscillator core, and the second coupling terminal of the third ring oscillator core, respectively. The output terminal of the fifth inverter INV5 is connected to the first input terminal of the third coupler C3; The second input terminal of the third coupler C3 serves as the second coupling terminal of the first ring oscillator core, and the output terminal serves as the output terminal of the first ring oscillator core. The second ring oscillator core includes: The fourth coupler C4, the sixth coupler C6, the third inverter INV3, the sixth inverter INV6, and the eighth inverter INV8; among them, The input terminal of the third inverter INV3 is connected to the input signal IN2 and is connected to the output terminal of the fourth coupler C4. The output terminal is connected to the first coupling terminal of the first ring oscillator core and the first coupling terminal of the third ring oscillator core, respectively. The input terminal of the eighth inverter INV8 is connected to the output terminal of the third inverter INV3, and the output terminal is connected to the second input terminal of the sixth coupler C6. The first input terminal of the sixth coupler C6 serves as the first coupling terminal of the second ring oscillator core, and its output terminal is connected to the input terminal of the sixth inverter INV6. The output terminal of the sixth inverter INV6 is connected to the first input terminal of the fourth coupler C4; The second input terminal of the fourth coupler C4 serves as the second coupling terminal of the second ring oscillator core, and the output terminal serves as the output terminal of the second ring oscillator core. The third ring oscillator core includes: The second coupler C2, the fifth coupler C5, the second inverter INV2, the seventh inverter INV7, and the ninth inverter INV9; among which... The input terminal of the seventh inverter INV7 is connected to the input signal IN3 and is connected to the output terminal of the ninth inverter INV9. The output terminal is connected to the second input terminal of the fifth coupler C5. The first input terminal of the fifth coupler C5 serves as the first coupling terminal of the third ring oscillator core, and its output terminal is connected to the input terminal of the second inverter INV2. The output of the second inverter INV2 is connected to the second input of the second coupler C2; The first input terminal of the second coupler C2 serves as the second coupling terminal of the third ring oscillator core, and its output terminal is connected to the input terminal of the ninth inverter INV9. The output terminal of the ninth inverter INV9 is connected to the second coupling terminal of the first ring oscillator core and the second coupling terminal of the second ring oscillator core, respectively, and serves as the output terminal of the third ring oscillator core.

2. The low phase noise kinked ring oscillator according to claim 1, characterized in that, In the first ring oscillator core, the input signal IN1 is output to the first input terminal of the first coupler C1 through the first inverter INV1, and coupled with the signal received at the second input terminal of the first coupler C1. The coupled signal is input to the fourth inverter INV4, and then input to the first input terminal of the third coupler C3 through the fifth inverter INV5, and coupled with the signal received at the second input terminal of the third coupler C3. The coupled signal is then fed back to the input terminal of the first inverter INV1 to form the closed-loop oscillation path of the first ring oscillator core.

3. A low-phase-noise kinked ring oscillator according to claim 1, characterized in that, In the second ring oscillator core, the input signal IN2 passes through the third inverter INV3 and the eighth inverter INV8, and is input to the second input terminal of the sixth coupler C6, where it is coupled with the signal received at the first input terminal of the sixth coupler C6. The coupled signal is then input through the sixth inverter INV6 to the first input terminal of the fourth coupler C4, where it is coupled with the signal received at the second input terminal of the fourth coupler C4. The coupled signal is then fed back to the input terminal of the third inverter INV3 to form the closed-loop oscillation path of the second ring oscillator core.

4. A low-phase-noise kinked ring oscillator according to claim 1, characterized in that, In the third ring oscillator core, the input signal IN3 passes through the seventh inverter INV7 and is input to the second input terminal of the fifth coupler C5, where it is coupled with the signal received at the first input terminal of the fifth coupler C5. The coupled signal then passes through the second inverter INV2 and is input to the second input terminal of the second coupler C2, where it is coupled with the signal received at the first input terminal of the second coupler C2. The coupled signal then passes through the ninth inverter INV9, and the signal output by the ninth inverter INV9 is fed back to the input terminal of the seventh inverter INV7 to form the closed-loop oscillation path of the third ring oscillator core.

5. A low-phase-noise kinked ring oscillator according to claim 1, characterized in that, All couplers in the first, second, and third ring oscillator cores have the same structure, and the couplers include: MOSFETs PM0, PM1, NM0, and NM1; among them, The source of the MOSFET PM0 is connected to the power supply voltage VDD, the gate is connected to the gate of the MOSFET NM0, serving as the first input terminal of the coupler, and the drain is connected to the source of the MOSFET PM1. The gate of MOS transistor PM1 is connected to the gate of MOS transistor NM1, serving as the second input terminal of the coupler, and the drain is connected to the drain of MOS transistor NM1, serving as the output terminal of the coupler. The source of the MOS transistor NM0 is grounded, and its drain is connected to the source of the MOS transistor NM1.

6. A low-phase-noise kinked ring oscillator according to claim 1, characterized in that, All inverters in the first, second, and third ring oscillator cores have the same structure. The inverters include: MOSFET PM2 and MOSFET NM2; among them, The source of the MOSFET PM2 is connected to the power supply voltage VDD, the gate is connected to the gate of the MOSFET NM2 and serves as the input terminal of the inverter, and the drain is connected to the drain of the MOSFET NM2 and serves as the output terminal of the inverter. The source of the MOS transistor NM2 is grounded.

Images