Abstract: A sigma-delta analog-to-digital (A/D) converter has an analog modulator, and an adjustable reference voltage circuit that provides a reference voltage to the analog modulator along a feedback path during A/D conversion. The reference voltage circuit includes a reference voltage generator that provides a plurality of positive and negative polarity signals to a gain multiplexer. The gain multiplexer selectively supplies a pair of positive and negative polarity signals to the analog modulator based on a select signal produced by a gain register and a microprocessor interface bus that together allow adjustment of the range of operation and performance of the sigma-delta A/D converter. This adjustment is made based on a particular application in which the converter is implemented; as the relative input power of an input signal changes, the sigma-delta A/D converter as dynamically adjusted, realizes higher performance.

Abstract: A serial fast propagation transmission switch responsive to a propagate input control signal to transmit a signal from the input to the output terminal in combination with a double inverting logic parallel to the transmission switch to limit the line impedance to a single stage impedance subsequent to the serial transmission.