Bridge sensor biasing and readout system

Patent metadata

Field	Value
Publication number	US-11604234-B2
Application number	US-202117523189-A
Country	US
Kind code	B2
Filing date	Nov 10, 2021
Priority date	Nov 10, 2020
Publication date	Mar 14, 2023
Grant date	Mar 14, 2023

Abstract

A sensor system for measuring a physical quantity includes: a bridge sensor having at least two terminal pairs, a current source for applying a bias current between the bias terminal pair, resulting in a differential sensor signal on a readout terminal pair, wherein the differential sensor signal is indicative for the physical quantity, and an amplifier comprising a first input node and a second input node for receiving the differential signal and at least one output node, wherein the amplifier is configured for amplifying the differential sensor signal and putting the resulting signal on the at least one output node, wherein the sensor system is configured such that, in operation, the amplifier is powered by at least part of the bias current.

First claim

The invention claimed is:

1. A sensor system for measuring a physical quantity, the sensor system comprising:
a bridge sensor comprising at least two terminal pairs,
a current source configured for applying a bias current between the terminals of one of the terminal pairs referred to as a bias terminal pair,
resulting in a differential sensor signal on a readout terminal pair different from the bias terminal pair,
wherein the differential sensor signal is indicative for the physical quantity, and
an amplifier comprising a first input node and a second input node for receiving the differential signal and at least one output node, wherein the amplifier is configured for amplifying the differential sensor signal and putting the resulting signal on the at least one output node,
wherein the sensor system is configured such that, in operation, the amplifier is powered by at least part of the bias current of the bridge sensor.

2. The sensor system according to claim 1 , wherein the amplifier comprises a differential transistor pair and wherein, during operation, the bias current is provided at a common mode point of the amplifier.

3. The sensor system according to claim 2 , the at least one output node is a first output node and a second output node and wherein said differential transistor pair comprises a first resistor (Rcm 3 ) between the first input node and the first output node and a second resistor (Rcm 4 ) between the second input node and the second output node.

4. The sensor system according to claim 1 , wherein the amplifier comprises a first part and a second part,
wherein the first part is configured for converting the differential sensor signal into a first current and a second current wherein a difference between the currents is indicative for the differential sensor signal,
and wherein the second part is configured for generating, from the first current and the second current, an output voltage which is indicative for the physical quantity.

5. The sensor system according to claim 1 , the sensor system comprising
a first voltage level shifter connected between a first terminal of the readout terminal pair and the first input node,
a second voltage level shifter connected between a second terminal of the readout terminal pair and the second input node,
wherein the voltage level shifters are configured for shifting a voltage level of signals of the readout terminal pair before amplifying the differential signal.

6. The sensor system according to claim 5 , wherein the voltage level shifters are comprising a first capacitor connected between the first input node and the first terminal of the readout terminal pair and a second capacitor connected between the second input node and the second terminal of the readout terminal pair.

7. The sensor system according to claim 5 , the sensor system comprising
a first resistor (Rcm 1 ) connected between the first input node and a reference voltage (Vcmref) or a voltage at the output node of the amplifier
a second resistor (Rcm 2 ) connected between the second input node and a reference voltage (Vcmref) or a voltage at the output node of the amplifier.

8. The sensor system according to claim 1 wherein said sensor system is configured for generating a chopped differential sensor signal, and/or wherein the amplifier comprises choppers for demodulation, and/or wherein the sensor system comprises choppers for demodulating the amplifier output.

9. The sensor system according to claim 1 , wherein the bridge sensor is a magnetic sensor.

10. The sensor system according to claim 9 , wherein the magnetic sensor is a magnetic Hall sensor, or a tunnel magnetoresistance bridge arrangement, or a giant magnetoresistance bridge arrangement.

11. The sensor system according to any of the claim 1 , wherein the bridge sensor is a pressure sensor.

12. The sensor system according to claim 1 wherein the bridge sensor, the current source and the amplifier are integrated in an integrated circuit.

13. The sensor system according to claim 1 , the sensor system comprising a plurality of bridge sensors, and configured for biasing the bias terminal pairs of the bridge sensors using the at least one current source and for reading out the readout terminal pairs of the bridge sensors.

14. The sensor system according to claim 13 , wherein the bridge sensors are arranged in a matrix configuration.

15. The sensor system according to claim 13 , configured for biasing and reading out the plurality of bridge sensors in parallel or in series.

Assignees

• Melexis Tech Sa
• Melexis Technologies Nv

Inventors

• Raman Johan
• Rombouts Pieter

Classifications

• G01R33/09

  Magnetoresistive devices · CPC title

• G01R33/091 Primary

  Constructional adaptation of the sensor to specific applications · CPC title

• G01R33/0023

  Electronic aspects, e.g. circuits for stimulation, evaluation, control; Treating the measured signals; calibration (G01R33/0017 takes precedence) · CPC title

• G01R15/202

  using Hall-effect devices (Hall elements in arrangements for measuring electrical power G01R21/08) · CPC title

• G01R33/0041

  using feed-back or modulation techniques · CPC title