Folded-cascode amplifier arrangement with cascode load means.

摘要

A folded-cascode amplifier arrangement includes first and second transistors (P2. N7) of complementary conductivity type and a constant current generator (30) for supplying quiescent current thereto. Signal current flowing in the first transistor (P2) is coupled to the second transistor (N7) through current steering at the inter-connection between their main conduction paths. The load means for the second transistor includes a cascode-connected third transistor (P7) for supplying load current thereto, which third transistor (P7) substantially increases the resistance of the load giving the advantage of correspondingly increasing the voltage gain of the amplifier arrangement. A further advantage is that the amplifier voltage gain transfer function exhibits a frequency response dominated by a single pole. The load means may include a fourth transistor (P4) in series with the third for yet further increasing the load impedance.