# US 12,184,318 B2 · Radio frequency switch

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- Number: US 12,184,318 B2
- Document ID: US12184318B2
- Status: Granted
- Kind: B2
- Application number: 17/688,916
- Filed: 2022-03-08
- Published: 2023-06-22
- Granted: 2024-12-31
- Earliest claimed: 2021-12-17
- Assignees: RichWave Technology Corp.
- Applicants: RichWave Technology Corp.
- Inventors: Yu-Siang Huang; Chih-Sheng Chen
- Web page: https://patentgrep.com/patent/US12184318B2

## CPC

- H04B 1/1615: {Switching on; Switching off, e.g. remotely (battery saving circuits associated with selective call operation H04W52/00; details of power consumption reduction in a PLL, H03L7/0802, H03L7/14, H03L2207/08, H03L2207/18; muting amplifiers by gain control see H03G3/34)}
- H04B 1/18: Input circuits, e.g. for coupling to an antenna or a transmission line (coupling networks between antennas or lines and receivers independent of the nature of the receiver H03H)
- H04B 1/44: Transmit/receive switching
- H04B: TRANSMISSION

## Abstract

A radio frequency (RF) switch includes a signal terminal, a reference voltage terminal and a shunt switch path. The shunt switch path includes a first sub-shunt circuit and a second sub-shunt circuit. The second sub-shunt circuit includes a first transistor and a second transistor coupled in parallel. When switched to a first state, the RF switch has first impedance; when switched to a second state, the RF switch has second impedance; and when switched to a third state, the RF switch has third impedance. The first impedance, the second impedance, and the third impedance are different.

## Claims

### Claim 1

A radio frequency (RF) switch comprising:
a signal terminal;
a reference voltage terminal; and
a shunt switch path coupled to the signal terminal and the reference voltage terminal, the shunt switch path comprising:
a first sub-shunt circuit; and
a second sub-shunt circuit comprising a first transistor and a second transistor coupled in parallel;
wherein when switched to a first state, the RF switch has first impedance; when switched to a second state, the RF switch has second impedance; and when switched to a third state, the RF switch has third impedance; and
the first impedance, the second impedance, and the third impedance are different.

### Claim 2 (depends on 1)

The RF switch of claim 1, wherein the first sub-shunt circuit comprises a plurality of stacked transistors.

### Claim 3 (depends on 2)

The RF switch of claim 2, wherein a size of the plurality of stacked transistors, a size of the first transistor and a size of the second transistor are different.

### Claim 4 (depends on 3)

The RF switch of claim 3, wherein the size of the plurality of stacked transistors exceeds the size of the first transistor; and the size of the first transistor exceeds the size of the second transistor.

### Claim 5 (depends on 3)

The RF switch of claim 3, wherein the size of the plurality of stacked transistors is equal to a sum of the size of the first transistor and the size of the second transistor.

### Claim 6 (depends on 2)

The RF switch of claim 2, wherein the first sub-shunt circuit further comprises a plurality of resistors, and each resistor is coupled to a first terminal and a second terminal of a corresponding stacked transistor of the plurality of stacked transistors.

### Claim 7 (depends on 1)

The RF switch of claim 1, wherein a size of the first transistor and a size of the second transistor are different.

### Claim 8 (depends on 7)

The RF switch of claim 7, wherein the size of the first transistor exceeds the size of the second transistor.

### Claim 9 (depends on 1)

The RF switch of claim 1, wherein a size ratio of the first transistor to the second transistor is 99:1.

### Claim 10 (depends on 1)

The RF switch of claim 1, wherein when turned on, the second transistor has an on-resistance substantially equal to a load resistance.

### Claim 11 (depends on 10)

The RF switch of claim 10, wherein the on-resistance is equal to 50 ohms.

### Claim 12 (depends on 1)

The RF switch of claim 1, wherein one of the first impedance, the second impedance, and the third impedance is equal to 50 ohms.

### Claim 13 (depends on 1)

The RF switch of claim 1, wherein the third impedance is matched to a load resistance.

### Claim 14 (depends on 1)

The RF switch of claim 1, wherein the third impedance is substantially equal to 50 ohms or 75 ohms.

### Claim 15 (depends on 1)

The RF switch of claim 1, further comprising a series switch path coupled to the signal terminal and a RF circuit.

### Claim 16 (depends on 1)

The RF switch of claim 1, wherein the signal terminal is coupled to an antenna.

### Claim 17 (depends on 1)

The RF switch of claim 1, wherein when the RF switch is switched to the first state, the first sub-shunt circuit is turned off, and the first transistor and the second transistor are turned off.

### Claim 18 (depends on 1)

The RF switch of claim 1, wherein when the RF switch is switched to the second state, the first sub-shunt circuit is turned on, and the first transistor and the second transistor are turned on.

### Claim 19 (depends on 1)

The RF switch of claim 1, wherein when the RF switch is switched to the third state, the first sub-shunt circuit is turned on, the first transistor is turned off, and the second transistor is turned on.

### Claim 20 (depends on 1)

The RF switch of claim 1, wherein the first impedance exceeds the third impedance, and the third impedance exceeds the second impedance.