Joint Implementation of the Sharing OTA and Bias Current Regulation Techniques in an 11-Bit 10 MS/s Pipelined ADC

Abstract

The power dissipation of a pipeline analog to digital converter (ADC) depends on different design strategies. In this brief communication, an 11-bit pipeline ADC consisting of five stages with 2.5 effective bit resolution is described. The circuit combines two main techniques to improve power dissipation, such as sharing OTAs between adjacent ADC stages and dynamic regulation of the OTA biasing according to the stage and subcycle of operation. To reduce the charge injection effect caused by the OTA sharing added circuitry, the ADC uses a topology based on four-input OTAs to reduce the number of transmission gates. The ADC has been fabricated using a standard 0.35 µm CMOS process. It consumes 17.85 mW at 10 MSample/s sampling rate. With this resolution and sampling rate, the measurement results show that it achieves 58.20 dB SNDR and 9.38 bit ENOB at 1 MHz input frequency.