Drive sense circuit

Patent metadata

Field	Value
Publication number	US-12025646-B2
Application number	US-202217649887-A
Country	US
Kind code	B2
Filing date	Feb 3, 2022
Priority date	Nov 19, 2018
Publication date	Jul 2, 2024
Grant date	Jul 2, 2024

Abstract

A method includes providing, by a signal source circuit of a sensing circuit, a signal to a sensor via a conductor. When the sensor is exposed to a condition and is receiving the signal, an electrical characteristic of the sensor affects the signal. The signal includes at least one of: a direct current (DC) component and an oscillating component. When the sensing circuit is in a noisy environment, transient noise couples with the signal to produce a noisy signal. The method further includes comparing, by a transient circuit of the sensing circuit, the noisy signal with a representation of the noisy signal. When the noisy signal compares unfavorably with the representation of the noisy signal, supplying, by the transient circuit, a compensation signal to the conductor. A level of the compensation signal corresponds to a level at which the noisy signal compares unfavorably with the representation of the noisy signal.

First claim

What is claimed is:

1. A drive sense circuit comprises:
a voltage follower circuit operable, when coupled to a sensor that is operable to sense a condition, to:
receive a voltage reference signal that includes an oscillating component;
generate an output voltage that follows the reference voltage signal;
drive a current (I 3 ) to the sensor based on the output voltage;

a current source operably coupled to the voltage follower circuit, wherein the current source sinks a current (I 2 ) from the voltage follower;
a sensing load coupled to the voltage follower, the current source, and a supply voltage, wherein the sensing load produces a sensed voltage based on a combination of currents I 2 and I 3 and on impedance of the sensing load, wherein the sensed voltage represents the condition sensed by the sensor; and
an analog to digital converter operably coupled to convert the sensed voltage into a digital value.

2. The drive sense circuit of claim 1 further comprises:
the sensing load producing varying sensed voltages as impedance of the sensor changes.

3. The drive sense circuit of claim 1 , wherein the voltage follower comprises:
an operational amplifier, wherein a first input is configured to receive the voltage reference signal;
a transistor, wherein a gate of the transistor is coupled to an output of the operational amplifier, wherein a source of the transistor is coupled to a second input of the operational amplifier and to the sensor, and wherein a drain of the transistor is coupled to the sensing load.

4. The drive sense circuit of claim 1 , wherein the voltage follower comprises:
an operational amplifier, wherein a first input is configured to receive the voltage reference signal, wherein an output of the operational amplifier is coupled to a second input of the operational amplifier, to the sensor, and to the sensing load.

5. The drive sense circuit of claim 1 further comprises:
a current source operably coupled to an output of the voltage follower and the sensor.

6. The drive sense circuit of claim 1 , wherein the sensing load comprises a resistor.

7. The drive sense circuit of claim 1 , wherein the sensing load comprises a biased transistor.

8. The drive sense circuit of claim 1 further comprises:
the sensor including an electrode of a touch screen.

9. A data sensing circuit comprises:
a drive sense circuit that includes:
a voltage follower circuit operable, when coupled to a sensor that is operable to sense a condition, to:
receive a voltage reference signal that includes an oscillating component;
generate an output voltage that follows the reference voltage signal;
drive a current (I 3 ) to the sensor based on with the output voltage;
a current source operably coupled to the voltage follower circuit, wherein the current source sinks a current (I 2 ) from the voltage follower;

a sensing load coupled to the voltage follower, the current source, and a supply voltage, wherein the sensing load produces a sensed voltage based on a combination of currents I 2 and I 3 and on impedance of the sensing load, wherein the sensed voltage represents the condition sensed by the sensor; and
an analog to digital converter operably coupled to convert the sensed voltage into a digital value;
a variance determination module operably coupled to determine characteristic variances of the sensor based on the digital value; and
a variance interpretation module operably coupled interpret the characteristic variances to determine changes to a condition being sensed by the sensor.

10. The data sensing circuit of claim 9 further comprises:
the sensing load producing varying sensed voltages as impedance of the sensor changes.

11. The data sensing circuit of claim 9 , wherein the voltage follower comprises:
an operational amplifier, wherein a first input is configured to receive the voltage reference signal;
a transistor, wherein a gate of the transistor is coupled to an output of the operational amplifier, wherein a source of the transistor is coupled to a second input of the operational amplifier and to the sensor, and wherein a drain of the transistor is coupled to the sensing load.

12. The data sensing circuit of claim 9 , wherein the voltage follower comprises:
an operational amplifier, wherein a first input is configured to receive the voltage reference signal, wherein an output of the operational amplifier is coupled to a second input of the operational amplifier, to the sensor, and to the sensing load.

13. The data sensing circuit of claim 9 , wherein the drive sense circuit further comprises:
a current source operably coupled to an output of the voltage follower and the sensor.

14. The data sensing circuit of claim 9 , wherein the sensing load comprises a resistor.

15. The data sensing circuit of claim 9 , wherein the sensing load comprises a biased transistor.

16. The data sensing circuit of claim 9 further comprises:
the sensor including an electrode of a touch screen.

Assignees

• Sigmasense Llc

Inventors

• Huynh Phuong
• Gray Patrick Troy

Classifications

• H03K5/1252

  Suppression or limitation of noise or interference (specially adapted for transmission systems H04B15/00, H04L25/08) · CPC title

• H03M1/12

  Analogue/digital converters ({H03M1/001 – } H03M1/10 take precedence) · CPC title

• H03F2203/45116

  Feedback coupled to the input of the differential amplifier · CPC title

• H03F2200/129

  there being a feedback over the complete amplifier · CPC title

• H03K2005/00078

  Fixed delay · CPC title