Patent ID: 7994761

Claim:
A regulator comprising: a linear regulator comprising: a preamplifier stage; a first radio frequency (RF) transistor; a second RF transistor, wherein the first RF transistor and the second RF transistor are of the same type, wherein an output of the linear regulator is electrically connected to an input of the preamplifier stage, and wherein the first RF transistor and the second RF transistor are electrically connected in series between a positive supply voltage and a negative supply voltage; and a phase reversal circuit electrically connected between the preamplifier stage and a biasing terminal of the second RF transistor and configured to shift the phase of an output of the preamplifier by about 180°, wherein an output of the preamplifier stage is provided to a biasing terminal of the first RF transistor and to the phase reversal circuit, wherein the first and second RF transistors are connected such that: when an input to the preamplifier stage is greater than the output of linear regulator, the first RF transistor sources current to a load to drive the output of the linear regulator higher; when the input to the preamplifier stage is less than the output of the linear regulator, the second RF transistor sinks current from the load to drive the output of the linear regulator lower; and when an output current either sourced by the first RF transistor or sunk by the second RF transistor is equal to zero, the first RF transistor and the second RF transistor have a non-zero bias current; and a bias adjustment circuit electrically connected to sense a bias current of at least one of the group consisting of the first RF transistor and the second RF transistor if an output current of the linear regulator is about zero, wherein the bias adjustment circuit is configured to: compare the bias current to a reference bias current; and modify a dc shift of the output of the preamplifier stage when the bias current of the second transistor does not have a predetermined relationship to the reference bias current.