A 10 b 50 MS/s opamp-sharing pipeline A/D with current-reuse OTAs

A 10 b opamp-sharing pipeline analog-to-digital (A/D) using current-reuse operational transconductance amplifiers (OTA) with dual nMOS differential inputs is presented. The current-reuse OTA topology facilitates opamp-sharing between all of the consecutive pipeline stages, minimizing power consumption and die area. Analog transistors in the OTA are always biased in saturation ensuring no loss of settling time due to OTA power turn-on delays. The A/D is fabricated in a 0.18-μ m CMOS process and occupies an active die area of 0.7 mm ². At 50 MS/s, maximum SNDR of 58 dB (ENOB=9.3 b) is achieved with 9.2 mW analog power consumption on a 1.8 V supply.