Multi-phase oscillator capable of generating any phase

Abstract

The invention discloses a multiphase oscillator capable of generating any phase, which comprises a plurality of quadrature oscillators without phase mode ambiguity, the plurality of quadrature oscillators are arranged in sequence and keep consistent phase modes during working, and any two adjacent quadrature oscillators are coupled and connected through a phase shift coupling network and generate a phase difference. When the method is applied, the certainty of the output phase can be ensured, and meanwhile, the area is small and the phase noise is low.

Description

Technical Field

[0001] The invention relates to integrated circuit design technology, in particular to a multi-phase oscillator capable of generating any phase. Background Art

[0002] An oscillator is a device that converts DC into AC signal output without external signal excitation. The oscillator itself has positive feedback and a certain gain to overcome the loss in the circuit feedback path, so it can generate a self-sustaining and stable output oscillation signal. As one of the main types of oscillators, voltage-controlled oscillators are used in modules such as phase-locked loops and clock recovery circuits, and are one of the core modules of wireless communication systems. Figure 1 As shown in (a), the commonly used voltage-controlled oscillator includes an active circuit and an LCR resonant circuit, where the upper resonant circuit relies on the resonance of capacitor C and inductor L, and R is the equivalent resistance, which is used to characterize the energy loss during resonance; the negative resistance -R generated by the lower active circuit offsets the resistance generated by the resonant circuit and supplements the energy loss in the resonant circuit. Therefore, when the voltage-controlled oscillator oscillates stably, Figure 1 (b) f 0 The stable output at the resonance point, its oscillation frequency can be calculated as

[0003] Usually the clock signal output by the oscillator is a differential signal, that is, a two-phase output with a phase difference of 180°. When the number of output phases is greater than 2, that is, the phase difference between adjacent clock signals is less than 180°, it can be called a multi-phase clock signal, such as Figure 2 The waveform relationship between the conventional differential clock signal (two phases) and the fully orthogonal clock signal (four phases) is shown. Figure 2 (a) is the differential clock signal waveform, Figure 2 (b) is a fully orthogonal clock signal waveform). Multi-phase output oscillators are widely used in many key RF modules such as subharmonic mixers, analog-to-digital converters (ADCs), and clock data recovery (CDRs). Commonly used coupled LC oscillators or traveling wave oscillators generate multi-phase outputs.

[0004] The above-mentioned multi-phase signal is a clock signal with a fixed phase difference. In some application scenarios, a clock signal with a variable phase difference (phase shift) is also required, such as a phased array system using LO phase shifting. The multi-phase shiftable clock of this system is generated by cascading a clock source + phase shifter. If a multi-phase shiftable clock signal can be generated directly at the oscillator, it will inevitably simplify the design of the LO phase-shifted phased array and improve the overall performance of the system.

[0005] At present, in order to obtain a clock signal with a variable phase difference (phase shift), the existing multi-phase oscillator is mainly implemented in two ways: coupled LC oscillator and traveling wave oscillator. Among them, the schematic diagram of the coupled LC oscillator is as follows Figure 3As shown. N LC oscillators are coupled into a loop, and the output of each oscillator has a different phase. The multi-phase output generated by this method has the following advantages: (1) The number of output phases can be achieved by expanding the number of coupled oscillator cores; (2) Phase noise can be optimized due to the number of coupled oscillators. Ideally, N-core coupling can achieve 10logN dB phase noise suppression. However, the use of coupled LC oscillators requires additional coupling circuits and on-chip interconnects. The oscillator occupies a large chip area and can only generate multi-phase signals with fixed phase differences. In addition, the size relationship between the multiple phases generated by this circuit is uncertain, such as Figure 3 There is to and by to There are two phase modes, that is, there is mode ambiguity, which will lead to the problem of uncertainty in phase output.

[0006] The schematic diagram of the traveling wave oscillator is shown in Figure 4 As shown. Four pairs of active circuits provide negative resistance for oscillation and are evenly distributed on the loop formed by the differential transmission line. The four pairs of active circuits generate standing waves with different phases respectively, and superimpose them on the entire loop to form a traveling wave. Therefore, in the entire oscillation loop, phases with equal amplitudes and phases ranging from 0-360° will be generated. The number of phases generated by this method is not limited, and the overall area is smaller than that of the coupled LC oscillator. However, although the traveling wave oscillator can easily generate a large number of phase signals, the phase difference between these signals is still fixed; in addition, there is still a problem of mode ambiguity in the traveling wave oscillator. Summary of the invention

[0007] The purpose of the present invention is to solve the problem that the existing multi-phase oscillator can only generate multi-phase signals with fixed phase difference and has pattern ambiguity, and to provide a multi-phase oscillator that can generate arbitrary phases, which can achieve 360° arbitrary phase output without pattern ambiguity, can ensure the determinism of the output phase, and at the same time has a small area and low phase noise.

[0008] The purpose of the present invention is mainly achieved through the following technical solutions:

[0009] A multiphase oscillator capable of generating any phase includes a plurality of orthogonal oscillators without phase mode ambiguity. The plurality of orthogonal oscillators are arranged in sequence and the phase mode is kept consistent during operation. Any two adjacent orthogonal oscillators are coupled and connected via a phase shift coupling network to generate a phase difference. The present invention is composed of a plurality of orthogonal oscillators arranged in sequence and a phase shift coupling network for coupling two adjacent orthogonal oscillators and generating a phase difference. The orthogonal oscillators and the phase shift coupling network are placed alternately, and each orthogonal oscillator is used as a clock channel to generate an orthogonal clock signal. All orthogonal oscillator units operate in a single phase mode (i.e., without mode ambiguity). By configuring the phase shift coupling network, the outputs of two adjacent orthogonal oscillators have a phase difference θ, and the angle can cover the range of 0 to 360°, so it is an arbitrary phase generation.

[0010] Furthermore, the phase-shift coupling network is provided with four coupling channels, which respectively correspond to coupling channels when the phase difference is 0°, 90°, 180°, and 270°. The phase-shift coupling network controls the phase difference between two adjacent orthogonal oscillators by controlling the opening and closing of the four coupling channels and the coupling strength of each coupling channel.

[0011] Furthermore, the four coupling channels are coupling channel I, coupling channel II, coupling channel III and coupling channel IV, and the corresponding phase differences of coupling channel I, coupling channel II, coupling channel III and coupling channel IV are 0°, 90°, 180° and 270° respectively; wherein:

[0012] When the phase difference between two adjacent orthogonal oscillators needs to be controlled to be between 0° and 45°, the coupling channel I and the coupling channel II are turned on, the coupling channel III and the coupling channel IV are turned off, and the coupling strength of the coupling channel I is greater than the coupling strength of the coupling channel II;

[0013] When the phase difference between two adjacent orthogonal oscillators needs to be controlled to be between 45° and 90°, the coupling channel I and the coupling channel II are turned on, the coupling channel III and the coupling channel IV are turned off, and the coupling strength of the coupling channel I is less than the coupling strength of the coupling channel II;

[0014] When the phase difference between two adjacent orthogonal oscillators needs to be controlled to be between 90° and 135°, the coupling channel II and the coupling channel III are turned on, the coupling channel I and the coupling channel IV are turned off, and the coupling strength of the coupling channel II is greater than the coupling strength of the coupling channel III;

[0015] When the phase difference between two adjacent orthogonal oscillators needs to be controlled to be between 135° and 180°, the coupling channel II and the coupling channel III are turned on, the coupling channel I and the coupling channel IV are turned off, and the coupling strength of the coupling channel II is less than the coupling strength of the coupling channel III;

[0016] When the phase difference between two adjacent orthogonal oscillators needs to be controlled to be between 180° and 225°, the coupling channel III and the coupling channel IV are turned on, the coupling channel I and the coupling channel II are turned off, and the coupling strength of the coupling channel III is greater than the coupling strength of the coupling channel IV;

[0017] When the phase difference between two adjacent orthogonal oscillators needs to be controlled to be between 225° and 270°, the coupling channel III and the coupling channel IV are turned on, the coupling channel I and the coupling channel II are turned off, and the coupling strength of the coupling channel III is less than the coupling strength of the coupling channel IV;

[0018] When the phase difference between two adjacent orthogonal oscillators needs to be controlled to be between 270° and 315°, the coupling channel I and coupling channel IV are turned on, the coupling channel II and coupling channel III are turned off, and the coupling strength of coupling channel IV is greater than the coupling strength of coupling channel I;

[0019] When the phase difference between two adjacent orthogonal oscillators needs to be controlled to be between 315° and 360°, the coupling channel I and coupling channel IV are turned on, the coupling channel II and coupling channel III are turned off, and the coupling strength of coupling channel IV is less than the coupling strength of coupling channel I.

[0020] Furthermore, each of the coupling channels is implemented by any one coupling mode of capacitive coupling, resistive coupling, inductive coupling and transistor coupling, or a combination of two or more coupling modes.

[0021] Furthermore, the orthogonal oscillator includes an active circuit and a resonant circuit, and the active circuit is implemented by a cross-coupled NMOS active circuit, a cross-coupled PMOS active circuit, a cross-coupled CMOS active circuit or a cross-coupled triode active circuit.

[0022] Furthermore, the phase differences of the plurality of orthogonal oscillators are increased in arithmetic progression.

[0023] Furthermore, the orthogonal oscillator is provided with four output nodes, namely, I+, Q+, I-, and Q-, and the phase difference between any two adjacent orthogonal oscillators is the phase difference of the signals output at the same node.

[0024] In summary, the present invention has the following beneficial effects compared with the prior art: the traditional multi-phase oscillator generates a fixed phase, and the present invention adjusts the coupling relationship between two adjacent orthogonal oscillators by introducing a phase shift coupling network, thereby realizing the generation of 360° arbitrary phase. The orthogonal oscillator of the present invention adopts an orthogonal oscillator without phase pattern ambiguity, which not only ensures the determinism of the phase, but also improves the phase noise performance of the oscillator. The present invention simultaneously realizes 360° arbitrary phase output without pattern ambiguity, a smaller area, and low phase noise. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The drawings described herein are used to provide a further understanding of the embodiments of the present invention, constitute a part of this application, and do not constitute a limitation of the embodiments of the present invention. In the drawings:

[0026] Figure 1 It is a schematic diagram of an existing voltage-controlled oscillator and its resonance point;

[0027] Figure 2 A schematic diagram of the waveform relationship between a conventional oscillator differential clock signal and a fully orthogonal clock signal;

[0028] Figure 3 Schematic diagram of coupled LC oscillator;

[0029] Figure 4 is a schematic diagram of a traveling wave oscillator;

[0030] Figure 5 A schematic diagram of a specific embodiment of the present invention;

[0031] Figure 6 A schematic diagram of a specific embodiment of the present invention when two orthogonal oscillators are provided;

[0032] Figure 7 Schematic diagram for achieving phase-mode ambiguity-free for quadrature oscillators;

[0033] Figure 8 It is a schematic diagram of the configuration of arbitrary phase and phase shift coupling network;

[0034] Fig. 9 It is a schematic diagram of an active circuit implementation form of an orthogonal oscillator in a specific embodiment of the present invention;

[0035] Fig.10 It is a schematic diagram of the implementation form of the phase shift coupling network in a specific embodiment of the present invention. DETAILED DESCRIPTION

[0036] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with embodiments and drawings. The exemplary embodiments of the present invention and their description are only used to explain the present invention and are not intended to limit the present invention.

[0037] Example:

[0038] like Figure 5 As shown, a multiphase oscillator capable of generating any phase includes a plurality of orthogonal oscillators without phase mode ambiguity, the plurality of orthogonal oscillators are arranged in sequence, the phase modes of all the orthogonal oscillators are kept consistent when they are working, and any two adjacent orthogonal oscillators are coupled and connected through a phase shift coupling network to generate a phase difference. In the specific setting of this embodiment, the phase differences of the plurality of orthogonal oscillators are successively increased in equal steps. It should be noted that in order to ensure that the phase finally generated is determined and controllable, all the orthogonal oscillators in this embodiment must work in a determined and consistent phase mode.

[0039] To demonstrate the principle of arbitrary phase generation, Figure 6 As shown ( Figure 6 Only two orthogonal oscillators are configured in the circuit), each orthogonal oscillator unit can support orthogonal clock signal output, and the orthogonal oscillator has four output nodes, I+, Q+, I-, and Q-, which are the fixed multi-phase signal part. The phase difference θ between any two adjacent orthogonal oscillator units is defined as the signal phase difference output at the same node, Figure 6 The phase difference θ shown in is the phase difference of the output signals of the orthogonal oscillators 1 and 2 at the I+ node, and the phase difference θ is an adjustable phase. The size of θ can be configured through the phase shift coupling network, and can completely cover any value from 0 to 360°. Similarly, Figure 6 There is a phase difference θ between the Q+ node of orthogonal oscillator 1 and the Q+ node of orthogonal oscillator 2, between the I- node of orthogonal oscillator 1 and the I- node of orthogonal oscillator 2, and between the Q- node of orthogonal oscillator 1 and the Q- node of orthogonal oscillator 2.

[0040] The orthogonal oscillator without phase mode ambiguity used in this embodiment is implemented based on the existing technology, and its implementation principle is as follows: Figure 7 As shown, Figure 7 Zhong|Z 01 / 02 |The two corresponding points on the curve are the states where the orthogonal oscillator with mode ambiguity works in phase mode one and mode two respectively, and the impedance of the two is consistent with no obvious difference. The specific implementation method of the orthogonal oscillator without phase mode ambiguity is: the quality factor (i.e., Q value) of phase mode one and phase mode two is reduced and increased respectively. In this way, when the orthogonal oscillator is working, the phase mode one with low Q value will be suppressed, and the phase mode two with high Q value will be retained, so as to achieve the purpose of achieving phase mode ambiguity of the orthogonal oscillator.

[0041] The phase shift coupling network of this embodiment is provided with four coupling channels, which correspond to the coupling channels when the phase difference is 0°, 90°, 180°, and 270° respectively. The phase shift coupling network controls the phase difference between two adjacent orthogonal oscillators by controlling the opening and closing of the four coupling channels and the coupling strength of each coupling channel. The coupling strength of each coupling channel is configurable. By configuring the strength combination of these coupling channels, a phase difference θ of any angle can be vector-synthesized. In order to further demonstrate the generation process of the phase difference θ, Figure 8The configuration of the θ and phase shift coupling network is shown. In this embodiment, the four coupling channels are coupling channel I, coupling channel II, coupling channel III and coupling channel IV, and the corresponding phase differences of coupling channel I, coupling channel II, coupling channel III and coupling channel IV are 0°, 90°, 180° and 270° respectively. In a specific implementation of this embodiment, when the phase difference between two adjacent orthogonal oscillators needs to be controlled to be between 0° and 45°, the coupling channel I and the coupling channel II are turned on, the coupling channel III and the coupling channel IV are turned off, and the coupling strength of the coupling channel I is greater than the coupling strength of the coupling channel II; when the phase difference between two adjacent orthogonal oscillators needs to be controlled to be between 45° and 90°, the coupling channel I and the coupling channel II are turned on, the coupling channel III and the coupling channel IV are turned off, and the coupling strength of the coupling channel I is less than the coupling strength of the coupling channel II; when the phase difference between two adjacent orthogonal oscillators needs to be controlled to be between 90° and 135°, the coupling channel II and the coupling channel III are turned on, the coupling channel I and the coupling channel IV are turned off, and the coupling strength of the coupling channel II is greater than the coupling strength of the coupling channel III; when the phase difference between two adjacent orthogonal oscillators needs to be controlled to be between 135° and 180°, the coupling channel II and the coupling channel III are turned on, the coupling channel I and the coupling channel IV are turned off, and the coupling strength of the coupling channel II is less than the coupling strength of the coupling channel III. strength; when the phase difference between two adjacent orthogonal oscillators needs to be controlled to be between 180° and 225°, the coupling channel III and the coupling channel IV are turned on, the coupling channel I and the coupling channel II are turned off, and the coupling strength of the coupling channel III is greater than the coupling strength of the coupling channel IV; when the phase difference between two adjacent orthogonal oscillators needs to be controlled to be between 225° and 270°, the coupling channel III and the coupling channel IV are turned on, the coupling channel I and the coupling channel II are turned off, and the coupling strength of the coupling channel III is less than the coupling strength of the coupling channel IV; when the phase difference between two adjacent orthogonal oscillators needs to be controlled to be between 270° and 315°, the coupling channel I and the coupling channel IV are turned on, the coupling channel II and the coupling channel III are turned off, and the coupling strength of the coupling channel IV is greater than the coupling strength of the coupling channel I; when the phase difference between two adjacent orthogonal oscillators needs to be controlled to be between 315° and 360°, the coupling channel I and the coupling channel IV are turned on, the coupling channel II and the coupling channel III are turned off, and the coupling strength of the coupling channel IV is less than the coupling strength of the coupling channel I.

[0042] like Fig. 9As shown, the orthogonal oscillator of this embodiment includes an active circuit and a resonant circuit, wherein the active circuit providing negative resistance in the orthogonal oscillator is implemented by a cross-coupled NMOS active circuit, a cross-coupled PMOS active circuit, a cross-coupled CMOS active circuit, or a cross-coupled triode active circuit. Different active circuits have different performances such as phase noise and power consumption, and can be selected according to the performance requirements.

[0043] The configurable phase shift coupling network of this embodiment is used to couple two adjacent orthogonal oscillators and generate an arbitrary phase, such as Fig.10 As shown. Each coupling channel in the phase-shift coupling network is implemented by any one of the coupling modes of capacitive coupling, resistive coupling, inductive coupling and transistor coupling, or a combination of two or more coupling modes. When the phase-shift coupling network of this embodiment adopts capacitive coupling, the coupling strength is adjusted by changing the equivalent capacitance value; when the phase-shift coupling network of this embodiment adopts resistive coupling, the coupling strength is adjusted by changing the equivalent resistance value; when the phase-shift coupling network of this embodiment adopts inductive coupling, the coupling strength is adjusted by changing the inductive coupling coefficient; when the phase-shift coupling network of this embodiment adopts transistor coupling, the coupling strength is adjusted by changing the transistor input voltage. In this embodiment, when the coupling strength of the coupling channel is zero, the coupling channel is closed. Different coupling modes have different differences in area, noise, etc., and are selected according to actual needs.

[0044] The multiphase oscillator proposed in this embodiment realizes arbitrary phase output of multi-channel oscillators and supports the generation of orthogonal signals in each channel. By configuring a phase shift coupling network for coupling two adjacent orthogonal oscillator units, any phase can be synthesized between two adjacent orthogonal oscillators. This embodiment has definite phase information and can overcome the problem of phase mode ambiguity existing in most traditional solutions.

[0045] The performance comparison between this embodiment and the traditional multi-phase oscillator is shown in Table 1:

[0046] Table 1. Performance comparison of this invention with traditional oscillators

[0047]

[0048] As can be seen from Table 1, this embodiment can achieve arbitrary phase (phase shift) while still having excellent phase accuracy and area advantages. When this embodiment is applied specifically, by arranging multiple clock channels and completing phase generation, this solution can be used as a potential clock / phase shift solution for 5G / 6G phased arrays.

[0049] The specific implementation methods described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific implementation method 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 should be included in the scope of protection of the present invention.

Claims

1. A multiphase oscillator capable of generating any phase, characterized in that: It comprises a plurality of orthogonal oscillators without phase mode ambiguity, the plurality of orthogonal oscillators are arranged in sequence and keep the phase mode consistent during operation, and any two adjacent orthogonal oscillators are coupled and connected through a phase shift coupling network to generate a phase difference.

2. A multiphase oscillator capable of generating any phase according to claim 1, characterized in that: The phase-shift coupling network is provided with four coupling channels, which respectively correspond to coupling channels when the phase difference is 0°, 90°, 180°, and 270°. The phase-shift coupling network controls the phase difference between two adjacent orthogonal oscillators by controlling the opening and closing of the four coupling channels and the coupling strength of each coupling channel.

3. A multiphase oscillator capable of generating any phase according to claim 2, characterized in that: The four coupling channels are coupling channel I, coupling channel II, coupling channel III and coupling channel IV, and the corresponding phase differences of coupling channel I, coupling channel II, coupling channel III and coupling channel IV are 0°, 90°, 180° and 270° respectively; wherein: When the phase difference between two adjacent orthogonal oscillators needs to be controlled to be between 0° and 45°, the coupling channel I and the coupling channel II are turned on, the coupling channel III and the coupling channel IV are turned off, and the coupling strength of the coupling channel I is greater than the coupling strength of the coupling channel II; When the phase difference between two adjacent orthogonal oscillators needs to be controlled to be between 45° and 90°, the coupling channel I and the coupling channel II are turned on, the coupling channel III and the coupling channel IV are turned off, and the coupling strength of the coupling channel I is less than the coupling strength of the coupling channel II; When the phase difference between two adjacent orthogonal oscillators needs to be controlled to be between 90° and 135°, the coupling channel II and the coupling channel III are turned on, the coupling channel I and the coupling channel IV are turned off, and the coupling strength of the coupling channel II is greater than the coupling strength of the coupling channel III; When the phase difference between two adjacent orthogonal oscillators needs to be controlled to be between 135° and 180°, the coupling channel II and the coupling channel III are turned on, the coupling channel I and the coupling channel IV are turned off, and the coupling strength of the coupling channel II is less than the coupling strength of the coupling channel III; When the phase difference between two adjacent orthogonal oscillators needs to be controlled to be between 180° and 225°, the coupling channel III and the coupling channel IV are turned on, the coupling channel I and the coupling channel II are turned off, and the coupling strength of the coupling channel III is greater than the coupling strength of the coupling channel IV; When the phase difference between two adjacent orthogonal oscillators needs to be controlled to be between 225° and 270°, the coupling channel III and the coupling channel IV are turned on, the coupling channel I and the coupling channel II are turned off, and the coupling strength of the coupling channel III is less than the coupling strength of the coupling channel IV; When the phase difference between two adjacent orthogonal oscillators needs to be controlled to be between 270° and 315°, the coupling channel I and coupling channel IV are turned on, the coupling channel II and coupling channel III are turned off, and the coupling strength of coupling channel IV is greater than the coupling strength of coupling channel I; When the phase difference between two adjacent orthogonal oscillators needs to be controlled to be between 315° and 360°, the coupling channel I and coupling channel IV are turned on, the coupling channel II and coupling channel III are turned off, and the coupling strength of coupling channel IV is less than the coupling strength of coupling channel I.

4. A multiphase oscillator capable of generating any phase according to claim 2, characterized in that: Each of the coupling channels is implemented by any one coupling mode of capacitive coupling, resistive coupling, inductive coupling and transistor coupling, or a combination of two or more coupling modes.

5. A multiphase oscillator capable of generating any phase according to claim 1, characterized in that: The orthogonal oscillator comprises an active circuit and a resonant circuit. The active circuit is implemented by a cross-coupled NMOS active circuit, a cross-coupled PMOS active circuit, a cross-coupled CMOS active circuit or a cross-coupled triode active circuit.

6. A multiphase oscillator capable of generating any phase according to claim 1, characterized in that: The phase differences of the plurality of orthogonal oscillators are increased in sequence and in equal steps.

7. A multiphase oscillator capable of generating any phase according to any one of claims 1 to 6, characterized in that: The orthogonal oscillator is provided with four output nodes, namely, I+, Q+, I-, and Q-. The phase difference between any two adjacent orthogonal oscillators is the phase difference of the signals output at the same node.

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