# US 2021/0344327 A1 · Acoustic wave filter with temperature sensor

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- Number: US 2021/0344327 A1
- Document ID: US20210344327A1
- Status: Published application
- Kind: A1
- Application number: 17/364,567
- Filed: 2021-06-30
- Published: 2021-11-04
- Earliest claimed: 2016-12-21
- Assignees: Skyworks Solutions, Inc.
- Applicants: Skyworks Solutions, Inc.
- Inventors: Joshua James Caron; Joel Anthony Penticoff
- Web page: https://patentgrep.com/patent/US20210344327A1

## CPC

- H03H 9/6489: {Compensation of undesirable effects}
- H03F 1/56: Modifications of input or output impedances, not otherwise provided for
- H03F 3/195: in integrated circuits
- H03F 3/245: {with semiconductor devices only}
- H03F 3/72: Gated amplifiers, i.e. amplifiers which are rendered operative or inoperative by means of a control signal
- H03H 9/02685: {Grating lines having particular arrangements}
- H03H 9/02834: {of temperature influence (cut angles H03H9/02543)}
- H03H 9/02992: {Details of bus bars, contact pads or other electrical connections for finger electrodes}
- H03H 9/25: Constructional features of resonators using surface acoustic waves {(devices for manipulating acoustic surface waves in general G10K11/36)}
- H03H 9/6483: {Ladder SAW filters}
- H03H 9/725: {Duplexers}
- H04B 1/40: Circuits
- H01Q 1/242: {specially adapted for hand-held use}
- H03F 3/19: with semiconductor devices only
- H03F 2200/111: the amplifier being a dual or triple band amplifier, e.g. 900 and 1800 MHz, e.g. switched or not switched, simultaneously or not
- H03F 2200/129: there being a feedback over the complete amplifier
- H03F 2200/171: A filter circuit coupled to the output of an amplifier
- H03F 2200/447: the amplifier being protected to temperature influence
- H03F 2200/451: the amplifier being a radio frequency amplifier
- H03F 2203/7209: the gated amplifier being switched from a first band to a second band
- H03H 9/1064: {for surface acoustic wave [SAW] devices}
- H04M 1/0202: {Portable telephone sets, e.g. cordless phones, mobile phones or bar type handsets (constructional features of telephone transmitters or receivers, e.g. of speakers or microphones H04M1/03)}
- H03H: IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS (waveguides, resonators, lines or other devices of the waveguide type H01P)
- H03F: AMPLIFIERS
- H04B: TRANSMISSION
- H01Q: ANTENNAS, i.e. RADIO AERIALS (radiators or antennas for microwave heating H05B6/72)
- H04M: TELEPHONIC COMMUNICATION (circuits for controlling other apparatus via a telephone cable and not involving telephone switching apparatus G08)

## Abstract

Aspects of this disclosure relate to a surface acoustic wave filter with an integrated temperature sensor. The integrated temperature sensor can be a resistive thermal device configured as a reflective grating for a surface acoustic wave resonator, for example. A radio frequency system can provide over temperature protection by reducing a power level of a radio frequency signal provided to the surface acoustic wave filter responsive to an indication of temperature provided by the integrated temperature sensor satisfying a threshold.

## Claims

### Claim 1

(canceled)

### Claim 2

A method of over temperature protection for an acoustic wave filter, the method comprising:
detecting an over temperature condition associated with an acoustic wave filter, the acoustic wave filter including a plurality of acoustic wave resonators, and the acoustic wave filter being a transmit filter; and
in response to the detecting the over temperature condition, reducing a power level of a radio frequency signal provided to the acoustic wave filter.

### Claim 3 (depends on 2)

The method of claim 2 wherein the reducing the power level includes decoupling a power amplifier from the acoustic wave filter.

### Claim 4 (depends on 2)

The method of claim 2 wherein the reducing the power level includes reducing a power level of an input signal to a power amplifier.

### Claim 5 (depends on 2)

The method of claim 2 wherein the reducing the power level includes attenuating an output signal from a power amplifier.

### Claim 6 (depends on 2)

The method of claim 2 wherein the reducing the power level includes reducing a duty cycle of a power amplifier.

### Claim 7 (depends on 2)

The method of claim 2 wherein the detecting the over temperature condition is based on a signal provided by a resistive thermal device, and the resistive thermal device is arranged as a reflective grating for at least one of the plurality of acoustic wave resonators.

### Claim 8 (depends on 2)

The method of claim 2 wherein the detecting the over temperature condition is based on a signal provided by a resistive thermal device having a resistance in range from 1 kΩ to 10 kΩ.

### Claim 9

A radio frequency system with over temperature protection, the radio frequency system comprising:
an acoustic wave filter configured to filter a radio frequency signal, the acoustic wave filter including a plurality of acoustic wave resonators, and the acoustic wave filter being a transmit filter; and
an over temperature circuit configured to detect an over temperature condition associated with the acoustic wave filter, and to cause a power level of the radio frequency signal to be reduced responsive to detecting the over temperature condition.

### Claim 10 (depends on 9)

The radio frequency system of claim 9 further comprising a transmit signal path including a power amplifier, the transmit path configured to provide the radio frequency signal to the acoustic wave filter, and the transmit signal path configured to receive an output signal of the over temperature circuit.

### Claim 11 (depends on 9)

The radio frequency system of claim 9 wherein the acoustic wave filter includes a resistive thermal device arranged as a reflective grating of at least one of the plurality of acoustic wave resonators, and the over temperature circuit is configured to receive an indication of temperature from the resistive thermal device.

### Claim 12 (depends on 11)

The radio frequency system of claim 11 wherein the resistive thermal device has a resistance of at least 500 Ω.

### Claim 13 (depends on 9)

The radio frequency system of claim 9 wherein the acoustic wave filter includes a resistive thermal device arranged as a reflective grating of at least two of the plurality of acoustic wave resonators, and the over temperature circuit is configured to receive an indication of temperature from the resistive thermal device.

### Claim 14 (depends on 9)

The radio frequency system of claim 9 further comprising a thermocouple connected to a port of the acoustic wave filter.

### Claim 15 (depends on 9)

The radio frequency system of claim 9 further comprising a temperature sensor connected to a port of the acoustic wave filter, the temperature sensor including a resonator.

### Claim 16 (depends on 9)

The radio frequency system of claim 9 further comprising a temperature sensor connected between two sensing ports of the acoustic wave filter.

### Claim 17 (depends on 9)

The radio frequency system of claim 9 comprising a multiplexer that includes the acoustic wave filter.

### Claim 18 (depends on 9)

The radio frequency system of claim 9 wherein the over temperature circuit includes a comparator configured to compare an indication of temperature with a reference signal.

### Claim 19

A packaged module comprising:
an acoustic wave filter configured to filter a radio frequency signal, the acoustic wave filter including a plurality of acoustic wave resonators, and the acoustic wave filter being a transmit filter;
an over temperature circuit configured to detect an over temperature condition associated with the acoustic wave filter, and to cause a power level of the radio frequency signal to be reduced responsive to detecting the over temperature condition; and
a package enclosing the acoustic wave filter and the over temperature circuit.

### Claim 20 (depends on 19)

The packaged module of claim 19 further comprising a radio frequency switch connected to the acoustic wave filter.

### Claim 21 (depends on 20)

The packaged module of claim 20 further comprising a power amplifier configured to generate the radio frequency signal.