A quadrature enhanced ring oscillator based on in-phase injection coupling

Abstract

The application discloses a kind of based on in-phase injection coupling quadrature enhanced ring oscillator, belong to radio frequency integrated circuit technical field, comprising: ring oscillator circuit and quadrature coupler circuit;Ring oscillator circuit is used to generate oscillation signal, including cascaded two differential ring oscillator basic units, and each stage differential ring oscillator basic unit includes input pair transistor and negative resistance pair transistor;Quadrature coupler circuit includes coupling transistor: Q1, Q2 and Q3, four differential output nodes of first stage differential ring oscillator basic unit and second stage differential ring oscillator basic unit are connected respectively, and in-phase injection coupling structure is formed.Through introducing in-phase injection coupling structure in quadrature enhanced ring oscillator, high-precision phase locking and low phase noise are realized Collaborative optimization, on the premise of not consuming static power consumption, the phase difference of multiple-phase output signal is stably locked in by pure switch operation.

Description

Technical Field

[0001] This invention belongs to the field of radio frequency integrated circuit technology, and specifically relates to an orthogonal enhancement ring oscillator based on in-phase injection coupling. Background Technology

[0002] In the field of radio frequency integrated circuits, ring oscillators (ROS) are ideal choices for voltage-controlled oscillators (VCOs) in phase-locked loops (PLLs), frequency synthesizers, and wireless communication transceivers due to their compact structure, wide tuning range, and ease of integration. However, compared with LC-based oscillators, their inherently poor phase noise and high jitter become bottlenecks in high-performance applications. Especially in scenarios with stringent timing accuracy requirements, this performance disadvantage limits the widespread application of ROS PLLs. Furthermore, there are inherent contradictions in optimizing the performance of ROS. For example, achieving a wide frequency tuning range often leads to a deterioration in gain linearity, which in turn affects loop stability and noise performance. On the other hand, attempting to improve performance indicators such as injection locking range by reducing the quality factor of the resonant network or increasing the size of the injection transistor often results in new problems such as increased power consumption, increased parasitic capacitance, and decreased oscillation capability, making it difficult to balance power consumption, area, and performance.

[0003] While existing technologies improve ring oscillator performance through injection-locking techniques and effectively suppress phase noise, the locking range and phase noise suppression capabilities of traditional single-point injection methods remain insufficient. Existing technologies also attempt to extend the locking bandwidth by introducing multi-phase injection signals and complementary injection paths; however, such methods may introduce additional phase shifts or increase circuit complexity. On the other hand, in applications requiring high quadrature accuracy and multi-phase output, although ring oscillators naturally provide multi-phase clocks, process variations and environmental changes can introduce significant phase errors. Existing technologies compensate for this by integrating active calibration circuitry, but this implies more complex system design and control logic.

[0004] Therefore, those skilled in the art urgently need to provide a ring oscillator that, while maintaining its inherent advantages, fundamentally solves the performance contradictions between phase noise, jitter, tuning linearity, and injection lock range, thereby meeting the stringent requirements of modern communication systems for high-frequency, high-precision clock signals. Summary of the Invention

[0005] To address the aforementioned problems in the prior art, this invention provides an orthogonal enhancement ring oscillator based on in-phase injection coupling. The technical problem to be solved by this invention is achieved through the following technical solution:

[0006] This invention provides an orthogonal enhancement ring oscillator based on in-phase injection coupling, comprising: a ring oscillator circuit and an orthogonal coupler circuit;

[0007] A ring oscillator circuit is used to generate an oscillation signal. It includes two cascaded differential ring oscillator basic units. Each differential ring oscillator basic unit includes an input pair transistor and a negative resistance pair transistor. The input pair transistor is used to input the differential signal, and the negative resistance pair transistor is used to provide oscillation energy.

[0008] Orthogonal coupler circuits include coupling transistors: , , and The coupling transistor is connected to the four differential output nodes of the first-stage differential ring oscillator basic unit and the second-stage differential ring oscillator basic unit to form an in-phase injection coupling structure, which is used to generate and maintain the coupling between the four differential output nodes. The fixed phase difference.

[0009] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0010] This invention provides an orthogonal enhancement ring oscillator based on in-phase injection coupling, wherein the ring oscillator circuit includes two cascaded differential ring oscillator basic units, each differential ring oscillator basic unit includes an input pair transistor and a negative resistance pair transistor, and the orthogonal coupler circuit includes a coupling transistor. , , and By connecting to the four differential output nodes of the first-stage differential ring oscillator basic unit and the second-stage differential ring oscillator basic unit, an in-phase injection coupling structure is formed. By introducing an in-phase injection coupling structure into the quadrature enhancement-type ring oscillator, a synergistic optimization of high-precision phase locking and low phase noise is achieved. Without consuming static power, the phase difference of the multiphase output signals is stably locked at a specific value through pure switching operation. .

[0011] Furthermore, the coupling strength of the in-phase injection coupling structure can be adjusted by the size of the coupling transistor and can be directly extended to a multiphase calibration system to calibrate the phase mismatch caused by jitter, thereby suppressing phase noise. This provides a local oscillator signal generation scheme for high-frequency communication systems that combines high precision, low noise, low power consumption, and good scalability.

[0012] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0013] Figure 1 This is a schematic diagram of the ring oscillator circuit provided in an embodiment of the present invention;

[0014] Figure 2 This is a schematic diagram of the orthogonal coupler circuit provided in an embodiment of the present invention;

[0015] Figure 3 This is an equivalent circuit diagram of the basic unit of the differential ring oscillator provided in the embodiment of the present invention;

[0016] Figure 4 This is an equivalent circuit diagram of the orthogonal coupler circuit provided in the embodiments of the present invention;

[0017] Figure 5 This is a simulation result diagram of the orthogonal enhancement ring oscillator provided in the embodiment of the present invention. Detailed Implementation

[0018] 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.

[0019] Figure 1 This is an equivalent circuit diagram of the ring oscillator circuit provided in an embodiment of the present invention. Figure 2 This is an equivalent circuit diagram of the orthogonal coupler circuit provided in an embodiment of the present invention. For example... Figures 1-2 As shown, this embodiment of the invention provides an orthogonal enhancement ring oscillator based on in-phase injection coupling, including: a ring oscillator circuit 1 and an orthogonal coupler circuit 2;

[0020] The ring oscillator circuit 1 is used to generate an oscillation signal, including two cascaded differential ring oscillator basic units 10. Each differential ring oscillator basic unit 10 includes an input pair transistor and a negative resistance pair transistor, wherein the input pair transistor is used to input the differential signal, and the negative resistance pair transistor is used to provide oscillation energy.

[0021] The quadrature coupler circuit 2 includes a coupling transistor: , , and The coupling transistor is connected to the four differential output nodes of the first-stage differential ring oscillator basic unit 101 and the second-stage differential ring oscillator basic unit 102 to form an in-phase injection coupling structure, which is used to generate and maintain the coupling between the four differential output nodes. The fixed phase difference.

[0022] Specifically, the negative output terminal of the first-stage differential ring oscillator basic unit 101 and the positive input terminal of the second-stage differential ring oscillator basic unit 102 are connected to differential output node A; the negative output terminal of the second-stage differential ring oscillator basic unit 102 and the negative input terminal of the first-stage differential ring oscillator basic unit 101 are connected to differential output node B; the positive output terminal of the first-stage differential ring oscillator basic unit 101 and the negative input terminal of the second-stage differential ring oscillator basic unit 102 are connected to differential output node C; and the positive output terminal of the second-stage differential ring oscillator basic unit 102 and the positive input terminal of the first-stage differential ring oscillator basic unit 101 are connected to differential output node D.

[0023] Figure 3 This is an equivalent circuit diagram of the basic unit of the differential ring oscillator provided in an embodiment of the present invention. Further, as... Figure 3 As shown, in the basic unit of the differential ring oscillator, the negative resistance pair transistor includes , The input transistors include , ; gate connection The drain and the negative output terminal OUTN of the basic unit of the differential ring oscillator. gate connection The drain and the positive output port OUTP of the basic unit of the differential ring oscillator. The source pole and The sources are all connected to the power supply terminal VDD; The gate is connected to the negative input terminal INN of the basic differential ring oscillator unit. The gate is connected to the positive input terminal INP of the basic differential ring oscillator unit. drain connection The drain and the positive output terminal OUTP of the basic unit of the differential ring oscillator. drain connection The drain and the negative output terminal OUTN of the basic unit of the differential ring oscillator. The source pole and The source terminals are all connected to ground (GND).

[0024] It should be noted that negative resistance affects transistors. , It is a PMOS transistor, and the input pair transistor is... , It is an NMOS transistor.

[0025] Figure 4 This is an equivalent circuit diagram of the orthogonal coupler circuit provided in an embodiment of the present invention. For example... Figure 4 As shown, Both the gate and drain are connected to the differential output node A. Both the gate and drain are connected to the differential output node B. Both the gate and drain are connected to the differential output node C. Both the gate and drain are connected to the differential output node D; The source is connected to the differential output node B. The source is connected to the differential output node C. The source is connected to the differential output node D. The source is connected to the differential output node A, where the coupled transistor... , , and All are NMOS transistors.

[0026] Please continue reading Figure 2 and Figure 4 It should be understood that the gate and drain of each coupled transistor are shorted, and the source is connected to the gate and drain of the next coupled transistor. Therefore, each coupled transistor can be regarded as a two-terminal device. , , and These represent the current flowing through the coupled transistor. , , and The drain-source current is due to the in-phase injection coupling structure formed by the four coupled transistors connected end-to-end. , , and They are all equal.

[0027] When the quadrature enhancement ring oscillator is working, the coupling transistor switches on and off according to the instantaneous phase difference between the differential output nodes.

[0028] Taking differential output node A and differential output node D as an example, when the phase difference between these two differential output nodes is close to... hour, When the gate-source voltage reaches the conduction condition, the resulting injected current is in phase with the main oscillation current, thus locking the stable operating point of the quadrature enhancement ring oscillator at a precise value. Phase difference.

[0029] Furthermore, the voltage signals of the differential output nodes A, B, C, and D are as follows:

[0030] ;

[0031] ;

[0032] ;

[0033] ;

[0034] And coupled transistor The gate-source voltage satisfies:

[0035] ;

[0036] in, This indicates the swing of the output voltage signal of the quadrature enhancement ring oscillator. Represents angular frequency. , Indicates the oscillation frequency. Represents a time variable.

[0037] Performing trigonometric transformations on the above equation yields:

[0038] .

[0039] This indicates that the coupled transistor The phase of the gate-source voltage leads the phase of the source voltage signal. When the coupled transistor When operating in the saturation region, the drain current can be expressed as:

[0040] .

[0041] in, Indicates a coupled transistor electron mobility, Indicates a coupled transistor Capacitance per unit area of ​​the gate oxide layer, Indicates a coupled transistor The aspect ratio, Indicates a coupled transistor The width of the trench, Indicates a coupled transistor The length of the channel, Indicates a coupled transistor Threshold voltage.

[0042] Fourier analysis of the above equation shows that the injected... The fundamental component is in phase with the source voltage signal, forming an in-phase injection characteristic.

[0043] Phase locking can be described by the generalized Adler equation:

[0044] ;

[0045] In the formula, Indicates the relative phase difference. Represents the coupling coefficient. Indicates the first One leakage current, Indicates the first One reference phase, Indicates frequency difference.

[0046] When the quadrature enhancement ring oscillator reaches steady state When the Adler equation simplifies, it becomes:

[0047] .

[0048] By solving for the stable point in the above equation, it can be proved that if and only if At that time, the orthogonal enhancement ring oscillator satisfies the stability condition, namely:

[0049] .

[0050] The above mathematical analysis shows that the orthogonal enhancement ring oscillator provided by this invention guarantees... Stable locking of phase difference.

[0051] The orthogonal enhancement ring oscillator based on in-phase injection coupling provided by the present invention will be further illustrated below through simulation.

[0052] Specifically, the simulation was conducted based on a 0.18μm CMOS process model, with a power supply voltage of 1.2V and an operating temperature of 27℃. Figure 5 This is a simulation result graph of the orthogonal enhancement ring oscillator provided in an embodiment of the present invention, where the horizontal axis represents the offset frequency and the vertical axis represents the phase noise. Figure 5 As shown, the quadrature enhancement ring oscillator exhibits excellent performance characteristics at a center frequency of 250MHz. At a frequency offset of 1MHz, the phase noise reaches an excellent level of -110dBc / Hz, which verifies the effectiveness of the in-phase injection coupling structure in suppressing phase noise. Furthermore, simulation results show that the quadrature enhancement ring oscillator consumes a total current of 0.8mA under normal operating conditions, corresponding to a power consumption level of 0.96mW, demonstrating high energy efficiency.

[0053] Next, the quadrature accuracy of the quadrature enhancement ring oscillator was analyzed. Under the condition of process angle variation, the phase error between the four output signals (i.e., the voltage output signals at the four differential output nodes A, B, C, and D) remained within 1 degree, verifying the stable locking capability of the in-phase injection coupling structure for the quadrature phase relationship.

[0054] As can be seen, the orthogonal enhancement ring oscillator provided by this invention achieves excellent phase noise performance and orthogonality accuracy while maintaining low power consumption, meeting the design requirements. The simulation results are in high agreement with the theoretical analysis, verifying the technical advantages of the in-phase injection coupling structure.

[0055] As can be seen from the above embodiments, the beneficial effects of the present invention are as follows:

[0056] This invention provides an orthogonal enhancement ring oscillator based on in-phase injection coupling, wherein the ring oscillator circuit includes two cascaded differential ring oscillator basic units, each differential ring oscillator basic unit includes an input pair transistor and a negative resistance pair transistor, and the orthogonal coupler circuit includes a coupling transistor. , , and By connecting to the four differential output nodes of the first-stage differential ring oscillator basic unit and the second-stage differential ring oscillator basic unit, an in-phase injection coupling structure is formed. By introducing an in-phase injection coupling structure into the quadrature enhancement-type ring oscillator, a synergistic optimization of high-precision phase locking and low phase noise is achieved. Without consuming static power, the phase difference of the multiphase output signals is stably locked at a specific value through pure switching operation. .

[0057] Furthermore, the coupling strength of the in-phase injection coupling structure can be adjusted by the size of the coupling transistor and can be directly extended to a multiphase calibration system to calibrate the phase mismatch caused by jitter, thereby suppressing phase noise. This provides a local oscillator signal generation scheme for high-frequency communication systems that combines high precision, low noise, low power consumption, and good scalability.

[0058] In the description of this invention, the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. In addition, those skilled in the art can combine and integrate the different embodiments or examples described in this specification.

[0059] The above description, in conjunction with specific preferred embodiments, provides a further detailed explanation of the present invention. It should not be construed that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art, various simple deductions or substitutions can be made without departing from the concept of the present invention, and all such modifications and substitutions should be considered within the scope of protection of the present invention.

Claims

1. An orthogonal enhancement ring oscillator based on in-phase injection coupling, characterized in that, include: Ring oscillator circuit and quadrature coupler circuit; The ring oscillator circuit is used to generate an oscillation signal and includes two cascaded differential ring oscillator basic units. Each differential ring oscillator basic unit includes an input pair transistor and a negative resistance pair transistor, wherein the input pair transistor is used to input the differential signal and the negative resistance pair transistor is used to provide oscillation energy. The orthogonal coupler circuit includes a coupling transistor: , , and The coupling transistor is connected to the four differential output nodes of the first-stage differential ring oscillator basic unit and the second-stage differential ring oscillator basic unit to form an in-phase injection coupling structure, which is used to generate and maintain between the four differential output nodes. A fixed phase difference; The negative output terminal of the first-stage differential ring oscillator basic unit is connected to the positive input terminal of the second-stage differential ring oscillator basic unit at differential output node A; the negative output terminal of the second-stage differential ring oscillator basic unit is connected to the negative input terminal of the first-stage differential ring oscillator basic unit at differential output node B; the positive output terminal of the first-stage differential ring oscillator basic unit is connected to the negative input terminal of the second-stage differential ring oscillator basic unit at differential output node C; and the positive output terminal of the second-stage differential ring oscillator basic unit is connected to the positive input terminal of the first-stage differential ring oscillator basic unit at differential output node D. Both the gate and drain of the device are connected to the differential output node A. Both the gate and drain are connected to the differential output node B. Both the gate and drain of the device are connected to the differential output node C. Both the gate and drain are connected to the differential output node D; The source is connected to the differential output node B. The source is connected to the differential output node C. The source is connected to the differential output node D. The source of the transistor is connected to the differential output node A; wherein, the coupling transistor , , and All are NMOS transistors.

2. The orthogonal enhancement ring oscillator based on in-phase injection coupling according to claim 1, characterized in that, In the basic unit of the differential ring oscillator, the negative resistance pair transistor includes , The input pair transistors include , ; gate connection The drain of the differential ring oscillator and the negative output terminal OUTN of the basic unit. gate connection The drain of the differential ring oscillator and the positive output port OUTP of the basic unit. The source pole and The sources are all connected to the power supply terminal VDD; The gate is connected to the negative input terminal INN of the differential ring oscillator basic unit. The gate is connected to the positive input terminal INP of the differential ring oscillator basic unit. drain connection The drain of the differential ring oscillator and the positive output terminal OUTP of the basic unit. drain connection The drain of the differential ring oscillator and the negative output terminal OUTN of the basic unit. The source pole and The source terminals are all connected to ground (GND).

3. The orthogonal enhancement ring oscillator based on in-phase injection coupling according to claim 2, characterized in that, Negative resistance to transistors , It is a PMOS transistor, and the input pair transistor is... , It is an NMOS transistor.

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