Method for determining the resistance deflection of a
Wheatstone bridge in a high-temperature environment, where The
Wheatstone bridge is powered by an ASIC circuit, and the output
voltage derived from the
Wheatstone bridge is used as an input
voltage signal (V). IN ) is passed to an ASIC
signal path and in a first step is converted into a current
signal, wherein in a second step the current signal is converted into a
time signal and the
time signal into a
pulse width modulated (PWM) signal, wherein the value of a
relative resistance deflection (ΔR / R) of the Wheatstone bridge is determined from the time lengths within the phase sequence of the
pulse width modulated signal, characterized by the fact that the input
voltage (V IN) before being passed to an
instrumentation amplifier (INA) to a first switching matrix (SW1), whereby the first switching matrix performs a time-controlled switching between the input voltage signal (V) IN ), an inverted input voltage signal (V INV ), a zero-voltage signal V IN =0, V inp =V inn =V REF / 2 and a span-voltage signal V IN =V REF / K is performed, where K is a device-dependent factor, wherein a second switching matrix initiates a charging and discharging cycle of a capacity (C) and a conversion of a differential signal between V inp and V inn a
time signal is generated and a digital component (DIG) switches between the charging and discharging cycles of the capacity, the
pulse width modulated signal (PWM) is output via a
comparator circuit (COMP) and the digital section (DIG).