Abstract: A method compensates for power supply voltage variation in a sensor output. The sensor output voltage is calibrated by obtaining the sensor outputs for full-scale and minimum offset sensor input signals at two power supply settings. Linear plots are formed from the full-scale and offset sensor output voltages. The sensor input for each sensor output reading is computed by obtaining the power supply voltage at the time of the sensor output voltage reading. The full-scale and offset output voltages for that power supply voltage are computed from the slopes of the linear plots. Finally, the ratio of the difference between the output voltage and offset output voltage divided by the difference between the full-scale and offset output voltages is computed to provide the compensation factor. The product of the computed ratio and the value of the full-scale sensor input is the compensated sensor input value.

Abstract: A pulse width modulator generates a linear sawtooth ramp waveform from a pulse signal to compare against an amplified input signal derived from a transducer output voltage signal. A first circuit generates the linear ramp waveform in response to the pulse signal. First and second amplifiers receive the differential transducer signal and provide the amplified input signal to one input of a comparator. The comparator has another input receiving the linear ramp waveform, and an output for providing a pulse width modulated output signal having a duty cycle proportional to the differential transducer signal. If the amplified input signal is greater than the sawtooth ramp then the output signal of the pulse width modulator goes to one state; otherwise, the output signal goes to an opposite state. The pulse width of the output signal is thus linearly proportional to the amplitude of the transducer output signal.

Abstract: An amplifier stage includes an operational amplifier having inverting and non-inverting inputs and an output and a resistive tee network coupled in the feedback loop between the inverting input and output to the non-inverting input which network is reference to the voltage applied at the non-inverting input for setting the gain of the amplifier stage. The amplifier stage may be combined with a differential pressure sensor for providing a single ended output voltage in response to the differential voltage outputs of the pressure sensor being applied to the inverting and non-inverting inputs of the amplifier stage.