CN-122001301-A - Oscillator circuit

Abstract

The invention discloses an oscillator circuit which comprises a first cross-coupled pair, a second cross-coupled pair, a resonant circuit coupled between the first cross-coupled pair and the second cross-coupled pair and a first injection circuit. The resonant circuit includes a first node outputting a first voltage signal and a second node outputting a second voltage signal. The first injection circuit is coupled to the first cross-coupled pair and injects a first compensation current having a first predetermined phase into a predetermined node of the first cross-coupled pair.

Inventors

• CHEN JUNYAN
• HONG ZHAOQING
• XUE YULI

Assignees

• 联发科技股份有限公司

Dates

Publication Date

20260508

Application Date

20251103

Priority Date

20250523

Claims (20)

1. 1. An oscillator circuit comprising: a first cross-coupled pair; A second cross-coupled pair; A resonant circuit coupled between said first cross-coupled pair and said second cross-coupled pair and comprising a first node outputting a first voltage signal and a second node outputting a second voltage signal, and A first injection circuit coupled to the first cross-coupled pair and injecting a first compensation current having a first predetermined phase to a predetermined node of the first cross-coupled pair.
2. 2. The oscillator circuit of claim 1, wherein the first cross-coupled pair comprises: a first transistor including a first electrode, a second electrode and a third electrode, and A second transistor including a first electrode, a second electrode, and a third electrode, Wherein said first electrode of said first transistor is coupled to said second electrode of said second transistor and said first electrode of said second transistor is coupled to said second electrode of said first transistor, Wherein said predetermined node is a node connected to said third electrode of said first transistor.
3. 3. The oscillator circuit of claim 2, wherein the first electrode of the first transistor is coupled to the first node of the resonant circuit and the first electrode of the second transistor is coupled to the second node of the resonant circuit, wherein the first voltage signal is provided to the first injection circuit.
4. 4. The oscillator circuit of claim 2, wherein the first injection circuit comprises: a filter circuit coupled to said third electrode of said first transistor and receiving said first voltage signal, and A pass circuit coupled to said filter circuit and providing a current path between said third electrode of said first transistor and a power supply node.
5. 5. The oscillator circuit of claim 2, wherein the first injection circuit injects the first compensation current in response to the first voltage signal, and the first predetermined phase is a 90 degree phase.
6. 6. The oscillator circuit of claim 2, further comprising: and a second injection circuit coupled to the third electrode of the second transistor and injecting a second compensation current having a second predetermined phase to the third electrode of the second transistor.
7. 7. The oscillator circuit of claim 6, wherein the second injection circuit provides the second voltage signal and the second injection circuit injects the second compensation current in response to the second voltage signal.
8. 8. The oscillator circuit of claim 1, wherein the second cross-coupled pair comprises: a third transistor including a first electrode, a second electrode, and a third electrode, and A fourth transistor comprising a first electrode, a second electrode and a third electrode, wherein said first electrode of said third transistor is coupled to said second electrode of said fourth transistor and said first electrode of said fourth transistor is coupled to said second electrode of said third transistor.
9. 9. The oscillator circuit of claim 8, further comprising: And a third injection circuit coupled to the third electrode of the third transistor and injecting a third compensation current having a third predetermined phase to the third electrode of the third transistor.
10. 10. The oscillator circuit of claim 9, wherein the third injection circuit provides the first voltage signal and the third injection circuit injects the third compensation current in response to the first voltage signal.
11. 11. The oscillator circuit of claim 8, further comprising: And a fourth injection circuit coupled to said third electrode of said fourth transistor and injecting a fourth compensation current having a fourth predetermined phase to said third electrode of said fourth transistor.
12. 12. The oscillator circuit of claim 11, wherein the fourth injection circuit provides the second voltage signal and the fourth injection circuit injects the fourth compensation current in response to the second voltage signal.
13. 13. An oscillator circuit comprising: a first cross-coupled pair; A second cross-coupled pair; A resonant circuit coupled between said first cross-coupled pair and said second cross-coupled pair and comprising a first node outputting a first voltage signal and a second node outputting a second voltage signal, and A plurality of injection circuits, each injection circuit coupled to one of said first cross-coupled pair and said second cross-coupled pair and injecting a compensation current having a predetermined phase to a predetermined node of one of said first cross-coupled pair and said second cross-coupled pair, Wherein one of the injection circuits comprises: a filter circuit coupled to said predetermined node of one of said first cross-coupled pair and said second cross-coupled pair and receiving one of said first voltage signal and said second voltage signal, and A pass circuit is coupled to the filter circuit and provides a current path between the predetermined node and the power supply node.
14. 14. The oscillator circuit of claim 13, wherein the injection circuit comprises: a first injection circuit coupled to said first cross-coupled pair; a second injection circuit coupled to said first cross-coupled pair; a third injection circuit coupled to the second cross-coupled pair, and And a fourth injection circuit coupled to said second cross-coupled pair.
15. 15. The oscillator circuit of claim 14, wherein the first cross-coupled pair comprises a first transistor comprising a first electrode, a second electrode, and a third electrode, and a second transistor comprising a first electrode, a second electrode, and a third electrode, wherein the first electrode of the first transistor is coupled to the second electrode of the second transistor, the first electrode of the second transistor is coupled to the second electrode of the first transistor, and the first injection circuit is coupled to the third electrode of the first transistor, and the second injection circuit is coupled to the third electrode of the second transistor.
16. 16. The oscillator circuit of claim 14, wherein the second cross-coupled pair comprises a third transistor comprising a first electrode, a second electrode, and a third electrode, and a fourth transistor comprising a first electrode, a second electrode, and a third electrode, wherein the first electrode of the third transistor is coupled to the second electrode of the fourth transistor, the first electrode of the fourth transistor is coupled to the second electrode of the third transistor, and the third injection circuit is coupled to the third electrode of the third transistor, the fourth injection circuit is coupled to the third electrode of the fourth transistor.
17. 17. The oscillator circuit of claim 14, wherein the first voltage signal is provided to a first injection circuit and a third injection circuit and the second voltage signal is provided to a second injection circuit and a fourth injection circuit.
18. 18. The oscillator circuit of claim 14, wherein the first injection circuit injects the first compensation current in response to the first voltage signal, the second injection circuit injects the second compensation current in response to the second voltage signal, the third injection circuit injects the third compensation current in response to the first voltage signal, and the fourth injection circuit injects the fourth compensation current in response to the second voltage signal.
19. 19. The oscillator circuit of claim 13, wherein the predetermined phase is a 90 degree phase.
20. 20. The oscillator circuit of claim 13, wherein a 180 degree phase difference exists between the first voltage signal and the second voltage signal.

Description

Oscillator circuit Cross reference The present application claims the benefit of U.S. provisional application No. 63/715,681 filed on month 411 of 2024. The content of this application is incorporated herein by reference. Technical Field The present invention relates to an oscillator circuit, and more particularly, to an oscillator circuit that suppresses flicker noise by phase-shifting self-injection. Background The current noise significantly affects the performance of the oscillator circuit, mainly in terms of the deterioration of the phase noise. When current noise is injected into the resonant circuit of the oscillator, the noise signal propagates through the resonant circuit and the gain path of the oscillator, affecting the output signal. The injected current noise affects the instantaneous phase of the oscillator, resulting in a phase deviation. The phase deviation of the oscillator is very sensitive to the timing of the current noise injection. For injection current noise with the same amplitude, different phase deviations may occur due to the different times of injection into the oscillator. The pulse sensitivity function (Impulse Sensitivity Function, ISF for short) is a mathematical model that describes the sensitivity of an oscillator to external disturbances, especially in phase noise analysis. ISF is denoted Γ (x) and is used to characterize the response of an oscillator to a unit pulse at different points within its period. The more symmetrical the ISF curve, the more flicker noise suppression capability of the oscillator circuit. However, the ISF curve is typically asymmetric due to the nonlinear nature of the oscillator circuit. Therefore, improving the symmetry of the ISF curve to enhance noise suppression capability is an important issue in oscillator circuit design Disclosure of Invention According to one embodiment of the present invention, an oscillator circuit includes a first cross-coupled pair, a second cross-coupled pair, a resonant circuit coupled between the first cross-coupled pair and the second cross-coupled pair, and a first injection circuit. The resonant circuit includes a first node outputting a first voltage signal and a second node outputting a second voltage signal. The first injection circuit is coupled to the first cross-coupled pair and injects a first compensation current having a first predetermined phase into a predetermined node of the first cross-coupled pair. According to another embodiment of the present invention, an oscillator circuit includes a first cross-coupled pair, a second cross-coupled pair, a resonant circuit coupled between the first cross-coupled pair and the second cross-coupled pair, and a plurality of injection circuits. The resonant circuit includes a first node outputting a first voltage signal and a second node outputting a second voltage signal. Each injection circuit is coupled to one of the first cross-coupled pair and the second cross-coupled pair and injects a compensation current having a predetermined phase to a predetermined node of one of the first cross-coupled pair and the second cross-coupled pair. One of the injection circuits includes a filter circuit and a pass circuit. The filter circuit is coupled to the predetermined node of one of the first and second cross-coupled pairs and receives one of the first and second voltage signals. The pass circuit is coupled to the filter circuit and provides a current path between the predetermined node and a power supply node. These and other objects of the present invention will become apparent to those skilled in the art upon a reading of the following detailed description of the preferred embodiments when taken in conjunction with the drawings and drawings. Drawings Fig. 1 shows a schematic diagram of an oscillator circuit according to one embodiment of the invention. Fig. 2 shows an exemplary circuit diagram of an injection circuit according to one embodiment of the invention. Fig. 3 shows an exemplary circuit diagram of an oscillator circuit according to a first embodiment of the invention. Fig. 4 shows an exemplary circuit diagram of an oscillator circuit according to a second embodiment of the invention. Fig. 5 depicts an exemplary circuit diagram of an injection circuit to illustrate the relationship between drain current and gate voltage, according to one embodiment of the invention. Fig. 6 is a schematic diagram showing the generation of a symmetric effective ISF (current injection sensitivity function) by injecting a compensation current having a predetermined phase, according to an embodiment of the present invention. Fig. 7 is a schematic diagram showing the phase of a load when observing a resonant circuit, according to one embodiment of the invention. Detailed Description Fig. 1 shows a schematic diagram of an oscillator circuit according to one embodiment of the invention. The oscillator circuit 100 may include a cross-coupled pair 110 and 120, a resonant circuit 130, and o