Oscillator circuit with withstand voltage mechanism
By designing an oscillation circuit that includes an inductor circuit, a cross-coupled transistor circuit, and a capacitor circuit, the contradiction between voltage swing and component withstand voltage and phase noise in the oscillation circuit was resolved. This achieved protection of the transistor from damage under small voltage swing and reduction of phase noise under large voltage swing.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- REALTEK SEMICON CORP
- Filing Date
- 2024-11-25
- Publication Date
- 2026-05-26
Smart Images
Figure CN122092801A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to oscillation circuit technology, and more particularly to an oscillation circuit with a voltage withstand mechanism. Background Technology
[0002] An oscillating circuit, particularly a capacitive-inductive oscillating circuit, is a circuit that comprises electrically coupled capacitors and inductors and operates based on oscillation effects. Oscillating circuits are widely used in, for example, but not limited to, oscillators, filters, tuners, and mixer circuits.
[0003] A larger voltage swing in the output signal of an oscillating circuit results in lower phase noise. However, a larger voltage swing can damage internal circuit components if their voltage withstand capability is insufficient. Conversely, reducing the voltage swing to avoid component damage increases phase noise. Therefore, circuit designers face a challenge in balancing phase noise and component voltage withstand requirements. Summary of the Invention
[0004] In view of the problems of the prior art, one object of the present invention is to provide an oscillation circuit with a withstand voltage mechanism to improve the prior art.
[0005] This invention includes an oscillation circuit with a withstand voltage mechanism, comprising: a first inductor circuit, a cross-coupled transistor circuit, a second inductor circuit, and a capacitor circuit. The first inductor circuit is electrically coupled to a pair of terminals. The cross-coupled transistor circuit is electrically coupled to the pair of terminals. The second inductor circuit is electrically coupled between the pair of terminals and a pair of oscillation output terminals. The capacitor circuit is electrically coupled between the pair of oscillation output terminals.
[0006] The features, implementation, and technical effects of this disclosure are described in detail below with reference to the accompanying drawings. Attached Figure Description
[0007] Figure 1 This invention shows a circuit diagram of an oscillation circuit with a withstand voltage mechanism in one embodiment of the invention.
[0008] Figure 2 This illustrates one embodiment of the present invention. Figure 1 The layout diagram of the oscillator circuit; and
[0009] Figure 3 This diagram shows waveforms of a first voltage and a second voltage in one embodiment of the present invention.
[0010] Symbol Explanation
[0011] 100: Oscillating circuit
[0012] 110: First Inductor Circuit
[0013] 120: Cross-coupled transistor circuit
[0014] 130: Second Inductor Circuit
[0015] 140: Capacitor Circuit
[0016] 200: First inductor coil
[0017] 210: Central government withdrawal
[0018] 220: Second inductor coil
[0019] CO1, CO2: Connecting ends
[0020] L11, L12, L21, L22: Inductors
[0021] MN1: First transistor
[0022] MN2: Second transistor
[0023] OT1, OT2: Oscillation output terminals
[0024] SW1: First maximum swing amplitude
[0025] SW2: Second largest swing amplitude
[0026] V1: First voltage
[0027] V2: Second voltage
[0028] VDD1: First power supply voltage
[0029] VDD2: Second power supply voltage Detailed Implementation
[0030] One object of the present invention is to provide an oscillation circuit with a withstand voltage mechanism, which prevents the transistors in the cross-coupled transistor circuit from being damaged due to exceeding the withstand voltage when the connection terminal operates with a small voltage swing, and at the same time reduces the phase noise at the oscillation output terminal when the oscillation output terminal operates with a large voltage swing.
[0031] Please refer to Figure 1 as well as Figure 2 . Figure 1 This diagram shows a circuit diagram of an oscillating circuit 100 with a voltage withstand mechanism, according to one embodiment of the present invention. Figure 2 This illustrates one embodiment of the present invention. Figure 1 The layout diagram of the oscillator circuit 100.
[0032] The oscillation circuit 100 includes: a first inductor circuit 110, a cross-coupled transistor circuit 120, a second inductor circuit 130, and a capacitor circuit 140.
[0033] The first inductor circuit 110 is electrically coupled between a pair of terminals CO1 and CO2. Figure 1 In the diagram, the first inductor circuit 110 is shown as including an inductor L11 electrically coupled between the first power supply voltage VDD1 and the connection terminal CO1, and an inductor L12 electrically coupled between the first power supply voltage VDD1 and the connection terminal CO2.
[0034] In practice, the first inductor circuit 110 can be as follows: Figure 2 As shown, this is achieved by a first inductor coil 200 to be equivalent. Figure 1 The inductors L11 and L12 are included, and a pair of terminals of the first inductor coil 200 are electrically coupled to the connection terminals CO1 and CO2. The first inductor coil 200 can be electrically coupled to the first power supply voltage VDD1 through the included central tap 210.
[0035] The cross-coupled transistor circuit 120 is electrically coupled between the connection terminals CO1, CO2 and the second power supply voltage VDD2.
[0036] like Figure 1 As shown, in this embodiment, the cross-coupled transistor circuit 120 includes a first transistor MN1 and a second transistor MN2. Figure 2 For simplicity, the cross-coupled transistor circuit 120 is shown as a block.
[0037] The first transistor MN1 has two first source / drain terminals electrically coupled to a first connection terminal (e.g., connection terminal CO1) of connection terminals CO1 and CO2 and a second power supply voltage VDD2. The second transistor MN2 is electrically coupled to two second source / drain terminals of connection terminals CO1 and CO2 (e.g., connection terminal CO2) and a second power supply voltage VDD2. The first gate of the first transistor MN1 is electrically coupled to the second connection terminal (e.g., connection terminal CO2), and the second gate of the second transistor MN2 is electrically coupled to the first connection terminal (e.g., connection terminal CO1).
[0038] exist Figure 1 In the embodiment, the first transistor MN1 and the second transistor MN2 are N-type transistors.
[0039] The second inductor circuit 130 is electrically coupled between the connection terminals CO1 and CO2 and a pair of oscillation output terminals OT1 and OT2. Figure 1In the diagram, the second inductor circuit 130 is shown as including an inductor L21 electrically coupled between the connection terminal CO1 and the oscillation output terminal OT1 and an inductor L22 electrically coupled between the connection terminal CO2 and the oscillation output terminal OT2.
[0040] In practice, the second inductor circuit 130 can be as follows: Figure 2 As shown, this is achieved by a second inductor coil 220 to achieve the equivalent Figure 1 The inductors L21 and L22 are provided, and a pair of first terminals of the second inductor coil 220 are electrically coupled to connection terminals CO1 and CO2, and a pair of second terminals of the second inductor coil 220 are electrically coupled to oscillation output terminals OT1 and OT2.
[0041] In one embodiment, the first area of the first inductor circuit 110 is greater than the second area of the second inductor circuit 130. In one embodiment, the first inductance value of the first inductor circuit 110 is greater than the second inductance value of the second inductor circuit 130.
[0042] Capacitor circuit 140 is electrically coupled between the oscillation output terminals OT1 and OT2. Figure 1 as well as Figure 2 For simplicity, the capacitor circuit 140 is shown as a block. However, in one embodiment, the capacitor circuit 140 may be a switching capacitor array or multiple voltage-controlled capacitors (not shown), and may optionally include an output buffer circuit (not shown). In another embodiment, the capacitor circuit 140 includes at least one metal-oxide-metal capacitor (MOMCAP).
[0043] With the above structure, the oscillation circuit 100 can operate according to the voltage difference between the first power supply voltage VDD1 and the second power supply voltage VDD2, wherein the first power supply voltage VDD1 can be, for example, but not limited to, a positive voltage, and the second power supply voltage VDD2 can be, for example, but not limited to, a ground potential. When the oscillation circuit 100 is running, the oscillation output terminals OT1 and OT2 respectively have a first voltage V1, and the connection terminals CO1 and CO2 respectively have a second voltage V2. The first maximum swing SW1 of the first voltage V1 is greater than the second maximum swing SW2 of the second voltage V2.
[0044] Please refer to the following at the same time Figure 3 . Figure 3 This diagram shows the waveforms of a first voltage V1 and a second voltage V2 in one embodiment of the present invention.
[0045] In one embodiment, the first inductor circuit 110 has a first inductance value L1, and the second inductor circuit 130 has a second inductance value L2.
[0046] The relationship between the second maximum swing SW2 of the second voltage V2 and the first maximum swing SW1 of the first voltage V1 is related to the inductance value, making the first maximum swing SW1 greater than the second maximum swing SW2. The relationship between the second maximum swing SW2 and the first maximum swing SW1 can be expressed by the following formula:
[0047] SW2=SW1×L1 / (L1+L2) (Equation 1)
[0048] According to the above structure, the oscillation circuit of the present invention can prevent the transistors in the cross-coupled transistor circuit from being damaged due to exceeding the withstand voltage when the connection terminal operates with a small voltage swing, and at the same time reduce the phase noise at the oscillation output terminal when the oscillation output terminal operates with a large voltage swing.
[0049] It should be noted that the above-described implementation is merely an example. In other embodiments, those skilled in the art can make modifications without departing from the spirit of the invention.
[0050] For example, the above embodiment is illustrated by describing a cross-coupled transistor circuit comprising a first transistor and a second transistor, both of which are N-type transistors. In other embodiments, after adjusting the connection relationship and voltage magnitude configuration between the first power supply voltage and the second power supply voltage and the oscillation circuit 100, the cross-coupled transistor circuit may comprise a first transistor and a second transistor, both of which are P-type transistors, or a pair of complementary metal-oxide-semiconductor (CMOS) transistors. The invention is not limited thereto. When the cross-coupled transistor circuit is implemented using CMOS transistors, Figure 2 The first inductor coil 200 shown will not include a center tap 210, nor will it need to receive the first power supply voltage VDD1.
[0051] Furthermore, Figure 2 The inductor shape shown is merely an example. In other embodiments, the inductor may be implemented in other shapes to form a resonant structure with the capacitor circuit, and this is not to be construed. Figure 2 Due to the shape limitations shown.
[0052] In summary, the oscillation circuit with a withstand voltage mechanism in this invention prevents the transistors in the cross-coupled transistor circuit from exceeding their withstand voltage and being damaged when the connection terminal operates with a small voltage swing, and at the same time reduces the phase noise at the oscillation output terminal when the oscillation output terminal operates with a large voltage swing.
[0053] Although the embodiments of this disclosure are described above, these embodiments are not intended to limit this disclosure. Those skilled in the art can make changes to the technical features of this disclosure based on its express or implied content. All such changes may fall within the scope of patent protection sought by this disclosure. In other words, the scope of patent protection of this disclosure shall be determined by the claims of this specification.
Claims
1. An oscillation circuit with a voltage holding mechanism, comprising: a first inductor circuit electrically coupled to a pair of connection terminals; a cross-coupled transistor circuit electrically coupled to the pair of connection terminals; a second inductor circuit electrically coupled between the pair of connection terminals and a pair of oscillation output terminals; and a capacitor circuit electrically coupled between the pair of oscillation output terminals.
2. The oscillation circuit of claim 1, wherein the cross-coupled transistor circuit comprises: a first transistor having two first source / drain electrically coupled to a first connection terminal of the pair of connection terminals and a second power supply voltage; and a second transistor having two second source / drain electrically coupled to a second connection terminal of the pair of connection terminals and the second power supply voltage; wherein a first gate of the first transistor is electrically coupled to the second connection terminal and a second gate of the second transistor is electrically coupled to the first connection terminal.
3. The oscillation circuit of claim 2, wherein the first transistor is a P-type transistor or an N-type transistor.
4. The oscillation circuit of claim 1, wherein the cross-coupled transistor circuit comprises a pair of complementary metal-oxide-semiconductor transistors.
5. The oscillation circuit of claim 1, wherein the first inductor circuit is a first inductor coil having a pair of end points electrically coupled to the pair of connection terminals.
6. The oscillation circuit of claim 1, wherein the second inductor circuit is a second inductor coil having a pair of first end points electrically coupled to the pair of connection terminals and a pair of second end points electrically coupled to the pair of oscillation output terminals.
7. The oscillation circuit of claim 1, wherein the capacitor circuit comprises at least one metal-oxide-metal capacitor.
8. The oscillation circuit of claim 1, wherein a first area of the first inductor circuit is greater than a second area of the second inductor circuit.
9. The oscillation circuit of claim 1, wherein a first inductance value of the first inductor circuit is greater than a second inductance value of the second inductor circuit.
10. The oscillation circuit of claim 1, wherein the capacitor circuit is a switched capacitor array or a plurality of voltage controlled capacitors, and optionally comprises an output buffer circuit.