A Highly Digital ADC With Enhanced Accuracy Using a Simple Ripple-Transferring Replica Pseudo PLL Technique

Abstract

We present a simple ripple-transferring replica pseudo phase-locked loop (PLL) technique for a highly digital ADC. The ADC is mainly constituted by main and replica pseudo PLLs. Compared with conventional techniques, this technique minimizes the main loop’s input ripple by means of inverting the replica loop’s input ripple and transferring it to the input of the main loop for the sum of the two ripples, so the accuracy of the ADC should be improved. To achieve the transfer function above, on the transferring path, a wide-band current mode amplifier is proposed. The proposed ADC is well suited for accuracy and power improved design. Fabricated with a 0.18- ${\mu }\text{m}$ CMOS process, the ADC achieves 65-dB SNDR while operating from a 1.2-V supply and using a 1-kHz input sine wave. Moreover, the power dissipation is only 11 ${\mu }\text{W}$ .