A Signal- and Transient-Current Boosting Amplifier for Large Capacitive Load Applications

A signal- and transient-current boosting (STCB) circuit is proposed and applied to a single-stage amplifier driving large capacitive loads. The proposed STCB circuit provides gain-bandwidth product (GBW) extension, slew-rate (SR) improvement and gain enhancement to the amplifier, with only slight alterations to the frequency response and transient response of the single-stage amplifier driving large capacitive loads. No on-chip capacitor or resistor is required. The STCB amplifier is fabricated in a commercial 0.18-μm CMOS technology. The active chip area is 0.00705 mm2. The supply is 1.8 V, and the current consumption is 20.3 μA. The capacitive load (CO) ranges from about 4.4 nF to 19 nF. The measured results with a ~ 19-nF load show the small-signal figure-of-merit (FOMS=GBW·CO/power) and the large-signal figure-of-merit (FOML=SR·CO/power) are 150345 MHz · pF/mW and 31213 V/μs·pF/mW, respectively, which correspond to improvements of 1.52 times and 1.36 times, respectively, to the prior art. The achieved phase margin and gain margin are 80.8 ° and 36.3 dB, respectively.