Unleashing the full power of feed-forward opamps: a 200MHz, fully differential, conditionally stable, 36dB gain PGA, using a four-stage multi-path 2.5V amplifier with double feed-forward compensation.

Abstract

With the continuous advancement of standards in telecommunication systems, requirements for analog circuitry will become ever more demanding. The newer standards not only utilize better modulation schemes, demanding less noise with higher linearity, but also require increased bandwidth from analog circuitry. This paper describes a highly linear, fully differential, feed-forward compensated, 200MHz Programmable Gain Amplifier capable of providing DC gain from −6dB up to 24dB with less than 1dB steps. The Programmable Gain Amplifier also has an option to enable high-pass-like signal transfer characteristics, done by a channel equalizing function, providing up to 36dB of gain at bandedge, to compensate for the losses associated with the propagation medium over frequency.