Dual-Path and Dual-Chopper Amplifier Signal Conditioning Circuit With Improved SNR and Ultra-Low Power Consumption for MEMS

A dual chopper amplifier (DCA) signal conditioning circuit with ultra-low power consumption is presented for microelectromechanical systems transducers. In the first stage, a low voltage high current amplifier is implemented, which improves the power consumption and noise floor. The second stage is composed of two parallel paths that improve SNR and provide two gain settings. To mitigate flicker noise, the amplifiers are chopped at two different frequencies, also providing an additional degree of freedom to the design. The circuit is designed in a 0.13 μm CMOS technology with 0.7 and 1.2 V supplies. The power consumption is of 2.66 μW at the 0.7 V supply and 3.26 μW at the 1.2 V supply. For a 1.6 mV input, in single path mode, the DCA has a gain of 34 dB, a bandwidth of 4 kHz and achieves an SNR of 89.06 dB in the frequency range of 0.5-4 kHz. In dual path mode, the DCA has a gain of 38 dB, a bandwidth of 3 kHz and achieves an SNR of 92.85 dB in the frequency range of 0.5-4 kHz. The effect of the chopper at the second amplifier in the single path and dual path modes is detailed.