Programmable-gain amplifiers based on AC couplings for continuous reception

A change in the programmable baseband gain during reception can abruptly alter the output DC level, which degrades signal quality. Programmable-gain amplifiers (PGA), which do not produce such transients, can be designed by utilizing AC couplings. Two such PGA topologies based on switched parallel transconductors and switched resistive voltage dividers are analyzed. The parasitic capacitances associated to the switched devices may produce small transients. The magnitude of the transients in the first PGA topology is analyzed.

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