Segmented attenuator with glitch reduction

摘要

A method and circuit for significantly reducing the switching transients of a digital step attenuator (DSA) by employing a segmented architecture that combines thermometer and binary coded stages. This approach reduces the number of attenuator stages switching at the same time and thus minimizes any glitch amplitude. Embodiments of a segmented DSA may be realized with “pi” and “bridged-T” attenuators, as well as with simple tuned L-pad attenuators combined in a resistor ladder network.

主权项

1. A segmented digital step attenuator circuit, including:
(a) at least one first segment comprising a plurality of individual thermometer encoded L-pad type bypassable attenuator circuits; and (b) at least one second segment comprising a plurality of individual binary encoded L-pad type bypassable attenuator circuits coupled in series with the at least one first segment of individual thermometer encoded L-pad type bypassable attenuator circuits; wherein applying a set of individual control signals to the first segments of individual thermometer encoded L-pad type bypassable attenuator circuits and a set of binary encoded control signals to the second segments of individual binary encoded L-pad type bypassable attenuator circuits selects an attenuation level for an input signal applied to the series coupled first and second segments.