Bulk-driven class AB fully-balanced differential difference amplifier

This paper presents a new low-voltage class AB fully-balanced differential difference amplifier (FB-DDA) employing the bulk-driven technique. At the FB-DDA differential pairs the bulk terminal of the MOS transistors are used as signal inputs in order to increase the common-mode input range under low supply voltage. At the class AB output stages the bulk terminal of the MOS transistors are used as control inputs in order to adjust the quiescent currents and compensate them against the process and temperatures (P/T) variation. The voltage supply of the FB-DDA is 0.7 V and the quiescent power consumption is 8.3 mu W. The open loop voltage gain is 68 dB and the gain-bandwidth product is 168 kHz for 10 pF capacitive load. The circuit performance was simulated in Cadence/Spectre environment using the TSMC 0.18 mu m CMOS process.