Low Voltage CMOS Power Amplifier with Rail-to-Rail Input and Output

This paper describes a CMOS power amplifier with rail-to-rail input and output, also suitable for low voltage applications. The amplifier uses Simple Miller Compensation with high bandwidth stage to robustly and power efficiently compensate the amplifier. Circuit also includes a common mode adapter block, based on resistive level shift network, to implement rail-to-rail input and optional adaptive biasing block, which can be used to extend bandwidth of the amplifier for large high frequency inputs in continuous-time applications. Measurement results show that the amplifier is capable of driving heavy resistive and capacitive loads having maximum output current exceeding 100 mA, when driving 1 nF || 10 Omega load from 3.0 V supply. Without adaptive biasing the linear amplifier achieves 5.7 MHz unity gain frequency and 61 phase margin when driving 1 nF || 1 kOmega load, while drawing 2.4 mA from 1.5 V supply.