A high current efficiency multipath nested feedforward compensation technique for two-stage amplifier

In this paper, a high current efficiency two-stage amplifier using multipath nested feedforward compensation (MNFC) method is proposed. For the purpose of achieving the high current efficiency, the first stage of the amplifier uses a recycling folded cascode amplifier (RFC) and a nested small-gain stage is added between the two stages of the amplifier so that there are two paths in the feedforward path. This two-stage amplifier improves the phase margin (PM) and extends the gain bandwidth (GBW) by using the MNFC technique which can eliminate the non-dominant pole. The chip area of this two-stage MNFC amplifier which using 0.18μm CMOS process is 0.01272 mm2. The simulated and measured results shows that the phase margin(PM), DC gain, gain-bandwidth(GBW), average 1% settling time, slew rate- (SR-) and slew rate+ (SR+) is 72.7°, 104.4 dB, 4.29 MHz, 246.2 ns, 16 V/μs, and 6.15 V/μs, respectively, when the load capacitance is 120 pF. The supply voltage of this circuit is 1.8 V and the power consumption is 0.13 mW.