Patent ID: 6982599

Claim:
An apparatus including a multistage differential amplifier with commonly controlled input and output common mode voltages, comprising: first and second differential input terminals to convey first and second phases of a differential input signal with an associated input common mode voltage; first and second differential output terminals to convey first and second phases of a differential output signal corresponding to said differential input signal with an associated output common mode voltage; a common mode control terminal to convey a common mode control signal for jointly controlling said input and output common mode voltages; and a plurality of differential amplifier circuits successively coupled between said common mode control terminal, said first and second differential input terminals, and said first and second differential output terminals, wherein each one of said plurality of differential amplifier circuits includes first and second amplifier input terminals, first and second amplifier output terminals, an input control terminal and an output control terminal, a first one of said plurality of differential amplifier circuits is coupled to said first and second differential input terminals via said first and second amplifier input terminals, and is further coupled to said common mode control terminal via said input control terminal, a last one of said plurality of differential amplifier circuits is coupled to said first and second differential output terminals via said first and second amplifier output terminals, and said first and second amplifier input terminals and said input control terminal of each succeeding one of said plurality of differential amplifier circuits is coupled to said first and second amplifier output terminals and said output control terminal, respectively, of a preceding one of said plurality of differential amplifier circuits.