# US 12,000,886 B2 · Self-test circuit and a method of checking the integrity of a signal through a signal path

> Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt

- Number: US 12,000,886 B2
- Document ID: US12000886B2
- Status: Granted
- Kind: B2
- Application number: 15/830,046
- Filed: 2017-12-04
- Published: 2019-06-06
- Granted: 2024-06-04
- Earliest claimed: 2017-12-04
- Assignees: Aktiebolaget Skf
- Applicants: Aktiebolaget SKF
- Inventors: Julian Franchitti
- Web page: https://patentgrep.com/patent/US12000886B2

## CPC

- G01R 31/2884: {using dedicated test connectors, test elements or test circuits on the IC under test (G01R31/2855 takes precedence)}
- G01R 29/22: Measuring piezoelectric properties
- G01R 31/2829: {Testing of circuits in sensor or actuator systems (testing of apparatus for measuring electric or magnetic variables G01R35/00; testing of indicating or recording apparatus G01D; in airbag systems B60R21/0173; checking gas analysers G01N33/007; monitoring or fail-safe circuits for electromagnets H01F7/1844)}
- G01R 31/2843: {In-circuit-testing}
- H10P 74/277: {Circuits for electrically characterising or monitoring manufacturing processes, e.g. circuits in tested chips or circuits in testing wafers}
- G01R: MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES (indicating correct tuning of resonant circuits H03J3/12)
- H10P: GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10

## Abstract

Examples provide for a self-test circuit. The self-test circuit comprises input circuitry; testing circuitry; and a circuit to be tested, coupled between the input and testing circuitry and comprising at least a piezoelectric crystal. The input circuitry is configured to generate and transfer a predefined electric signal comprising at least a sinusoidal signal through at least the piezoelectric crystal of the circuit to be tested to generate an output signal. The testing circuitry is configured to analyze the output signal.

## Claims

### Claim 1

A self-test circuit comprising:
input circuitry;
testing circuitry; and
a circuit to be tested coupled between the input circuitry and the testing circuitry and comprising a piezoelectric crystal;
wherein the input circuitry is configured to generate a predefined sinusoidal electric signal and to pass the electric signal through the piezoelectric crystal of the circuit to be tested, and
wherein the testing circuitry is configured to analyze the electric signal after the electric signal has passed through the piezoelectric crystal.

### Claim 2 (depends on 1)

The self-test circuit of claim 1, wherein the circuit to be tested further comprises at least one of a low-pass, bandpass, and a high-pass filter circuit.

### Claim 3 (depends on 1)

The self-test circuit of claim 1, wherein the testing circuitry is configured to perform signal amplitude or frequency assessments on the electric signal.

### Claim 4 (depends on 1)

The self-test circuit of claim 1, wherein the testing circuitry comprises a signal processor configured to convert the electric signal from time domain to frequency domain and to analyze the electric signal in the frequency domain.

### Claim 5 (depends on 1)

The self-test circuit of claim 1, wherein the input circuitry is configured to generate the at least one electric signal with a frequency greater than 0 Hz and less than a resonant frequency of the piezoelectric crystal.

### Claim 6 (depends on 1)

The self-test circuit of claim 1, wherein the input circuitry comprises a digital signal processor configured to generate a predefined digital signal and to convert the digital signal to the analog domain to generate the predefined electric signal.

### Claim 7 (depends on 1)

The self-test circuit of claim 1, further comprising a switch configured to select between a normal operation and a test mode, wherein, when in the test mode, the switch connects the input circuitry to the circuit to be tested and wherein the switch is configured to select the test mode at least until the electric signal reaches the testing circuitry.

### Claim 8

A method for self-testing a circuit comprising:
generating a predefined sinusoidal electric signal;
passing the predefined electric signal through a piezoelectric crystal of a circuit to be tested; and
analyzing the electric signal after the electric signal has passed through the piezoelectric crystal.

### Claim 9 (depends on 8)

The method of claim 8, further comprising filtering the electric signal before analyzing the electric signal.

### Claim 10 (depends on 8)

The method of claim 8, wherein analyzing the electric signal comprises performing signal amplitude or frequency assessments on the electric signal.

### Claim 11

A self-test circuit comprising:
input circuitry;
testing circuitry; and
a circuit to be tested coupled between the input circuitry and the testing circuitry, the circuit to be tested comprising a piezoelectric crystal and a filter;
wherein the input circuitry is configured to generate a predefined sinusoidal electric signal and to pass the sinusoidal electric signal through the piezoelectric crystal and the filter, and
wherein the testing circuitry is configured to analyze the sinusoidal electric signal after the sinusoidal electric signal has passed through the piezoelectric crystal and the filter.