A Multi-bit Switched Capacitor DAC with Robust Analog Background Calibration

A multi-bit switched-capacitor DAC with robust analog background calibration intended to be used as feedback DAC for multi-bit pipeline ADCs or broadband sigma delta ADCs with how oversampling ratio is presented in this paper. The accuracy of calibration is not limited by mismatch of charge injections. A multi-bit switched-capacitor DAC whose linearity is only limited by opamp DC gain is realized. Assuming mismatch in capacitor values, switch transistor threshold voltages and opamp offsets, simulation results show linearity improves by about 40dB to 15-bit after about 900 sampling clock periods.