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

Abstract

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 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> . The supply is 1.8 V, and the current consumption is 20.3 μA. The capacitive load (C <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">O</sub> ) 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·C <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">O</sub> /power) and the large-signal figure-of-merit (FOML=SR·C <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">O</sub> /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.