Low voltage gain boosting schemes for one stage operational amplifiers

Two simple schemes for boosting significantly the open loop gain of one stage op-amps without essential degradation of the phase margin are discussed. These are based on low voltage active current mirrors using multiple cascoded auxiliary amplifiers to achieve extremely high output resistance. Post-layout simulations show that open loop gain greater than 300 dB with phase margin greater 60° can be achieved in 0.5 μm CMOS technology.