Patent ID: 6157257
Filing Date: 2000-12-05
Classification: H03F

Abstract:
A folding amplifier comprising:a plurality of consecutive folding stages, each of the stages comprising a differentially coupled transistor pair to which is applied a differential signal consisting of the sum and difference of an input signal and a reference voltage which increases progressively for each successive one of said stages, thereby allowing no more than one said transistor pair to be in a balanced condition at any one time; andtail current switching means comprising:a single tail current input; anda plurality of switches, each of which is connected between a corresponding said transistor pair and the tail current input, wherein each of the switches is controlled, by the differential signal being applied to the corresponding transistor pair, in such a manner that tail current applied to the tail current input is routed primarily through the one of said switches connected to the transistor pair which is in said balanced condition.