Bridge sensor biasing and readout

Abstract

The present invention relates to a circuit (1) for biasing and reading out a bridge sensor structure (2). The circuit comprises at least two pairs of connection terminals (3), each pair adapted for connecting to complementary terminals of the bridge. The circuit comprises an excitation signal generator (4) for generating an excitation signal for biasing and / or exciting the bridge, in which the excitation signal is provided as a non-constant periodic continuous function of time. The circuit also comprises a detection circuit (5) for obtaining the sensor signal from the bridge sensor structure (2) by electrically connecting the detection circuit to any pair of connection terminals (3) while applying the excitation signal to another pair. The circuit comprises a switch unit (6) for switchingthe electrical excitation signal from being supplied to a first pair to another pair of the connection terminals and for switching the detection circuit from being connected to a second pair to another pair of the connection terminals, and a controller (7) for controlling the switch unit (6) to switch the first pair from being connected to the excitation signal generator (4) at a time when the generated excitation signal is in a predetermined signal range where the excitation signal value is substantially equal to zero.

Description

technical field [0001] The invention relates to the field of sensors. More specifically, it relates to circuits and methods for biasing and reading out signals from bridge sensor structures, such as circuits for biasing and reading out Wheatstone bridges or Hall sensor elements and methods. Background technique [0002] The use of resistive structures such as Hall plates or Wheatstone bridges for detecting physical quantities is known in the field of sensor technology. For example, a Wheatstone bridge can be used in a pressure sensor (eg using a piezoresistive element). Similarly, Hall elements can be used to measure magnetic fields in current sensors or angular position sensors. The passive resistive structures used in such sensors may require the application of an excitation signal, eg in the form of voltage or current, in order to detect the output signal. The term "biasing" refers to the process in which such an excitation signal, such as a voltage or current, is app...

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Problems solved by technology

Furthermore, low noise amplification methods known in the art may require continuous operation over a period of time to prevent noise aliasing due to sampling effects

Therefore, after settling to a low voltage, the output signal must be sensed over a sufficiently large time span, thus further limiting the maximum achievable spin speed while maintaining the noise at an acceptable level

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