PSRR enhancement technique using low voltage current source for single supply operational amplifiers

The paper analyzes the principle of the technique using low voltage current source to improve the power supply rejection ratio (PSRR) of operational amplifiers (OPAs). The technique has advantage of decreasing the parasitic gain from power supply with no detrimental effect on the output swing. A single supply two-stage Miller compensated OPA is presented as a prototyped circuit. The simulation results of the proposed OPA show that 38 dB and 17 dB improvement of PSRR at DC and 10MHz respectively compared with the OPA without the suggested circuit. Near rail-to-rail output swing and 489 MHz gain bandwidth (GBW) have been acquired to satisfy the large output swing and wideband application requirement.