The AD771x Series is a family of ADCs that are designedspecifically for low frequency, high accuracy industrialtransducer applications. Figure 1 shows a block diagramof one of these devices. The analog front end, which insome cases also includes excitation sources for sensors,accepts low level signals that can be amplified by theinternal programmable gain amplifier before beingapplied to a sigma-delta modulator. The pulse streamappearing at the output of this modulator is applied to adigital filter which produces a low-pass filtered, highresolution, serial output.