Bulk-driven fully differential difference amplifier for ultra-low voltage applications

This paper deals with the design and analysis of a fully differential difference amplifier (FDDA) based on a pseudo differential topology that was implemented in a 130 nm CMOS technology. The proposed FDDA can reliably work with its power supply voltage as low as 0.4 V. The FDDA was designed using the bulk-driven technique, and Rail-to-Rail (RtR) input voltage range was ensured through the use of bulk-driven input transistors. Additionally, the RtR input/output CMFB, based on FDDA topology, was proposed. The output voltage range is near RtR (±0.36 V). The CMRR and PSRR of 60.2 dB and 64.4 dB was achieved, respectively. The proposed FDDA shows very good linearity in wide output range, thus the THD of −156 dB@1 mV was reached. Furthermore, the proposed FDDA was used as a building block of an ultra-low voltage-to-frequency converter.