Amplifier system with current-mode servo feedback

Abstract

An amplifier apparatus including differential inputs disposed to receive a first and second input signal, a primary differential amplifier having inverting and non-inverting input nodes receiving the first and second input signal through respective first and second impedance elements and providing a main output signal, feedback circuitry disposed to sample the main output signal and convey complementary current-mode negative feedback signals to the inverting and non-inverting input nodes, wherein the current-mode feedback signals are each servo feedback signals having the same low-pass characteristic, a first controllable circuitry to adjust the input offset voltage of the primary differential amplifier, and a second controllable circuitry to compensate for variations in an input offset voltage and a bias current of the differential amplifier by changes in an operating environment.

1 . An amplifier apparatus comprising: 
 differential inputs disposed to receive a first and second input signal;    a primary differential amplifier having inverting and non-inverting input nodes receiving said first and second input signal through respective first and second impedance elements and providing a main output signal;    feedback circuitry disposed to sample said main output signal and convey complementary current-mode negative feedback signals to said inverting and non-inverting input nodes, wherein said current-mode feedback signals are each servo feedback signals having the same low-pass characteristic;    a controllable circuitry to adjust the input offset voltage of said primary differential amplifier; and    a controllable circuitry to compensate for variations in said input offset voltage and bias current of said differential amplifier by changes in an operating environment.    
   
   
       2 . The amplifier apparatus of  claim 1 , wherein said operating environment includes ambient temperature.