Design of low-voltage front-end interface for switched-opamp circuits

Switched-opamp technique is an effective technique for designing low-voltag e switched-capacitor circuits. The only drawback with this approach is the difficulty in designing the front-end interface to the external input. In t his paper, front-end interface structures with wide signal swing and no vol tage boosting are proposed. Based on a conventional 1.2-mum CMOS process, a front-end interface was designed and implemented. For a 1-V supply, the in terface dissipates 80 muW. The track mode THD was measured to be -78 dB for a 600-mV peak-to-peak output swing, and the maximum sampling rate was meas ured to be 600 kS/s for a capacitive load of 20 pF.