Low - Power Low - Voltage Chopped Ampli er with a New Class AB Output Stage

| This paper describes the principle and the design of a 0.5m CMOS, low-power, low-voltage, chopped ampliier for noise and ooset reduction in mixed analogue digital applications. The operation is based on chopping and dynamic element matching to reduce noise and ooset, without excessive increase of the charge injection residual ooset. It consists of a chopped transconductance stage and a new class AB stage capable of working at 1.3V supply voltage. The main goal is to achieve low residual oosets by chopping at high frequencies reducing at the same time the 1/f noise of the am-pliier. Loaded with a heavy load 32jj 300pF it has a 91dB open loop gain and a GBW of 1.8MHz. Simulations show a THD of-90dB for a 1k load and-83dB for a 32 load and 1KHz input signal. The simulated static ooset is 1.67mV. The simulated residual ooset is 450V at 10MHz chopping. At 1KHz chopping, the ooset becomes lower than 1V.