Switched-Capacitor Variable Gain Amplifier with Operational Amplifier Preset Technique

We present a novel operational amplifier preset technique for a switched‐capacitor circuit to reduce the acquisition time by improving the slewing. The acquisition time of a variable gain amplifier (VGA) using the proposed technique is reduced by 30% compared with a conventional one; therefore, the power consumption of the VGA is decreased. For additional power reduction, a programmable capacitor array scheme is used in the VGA. In the 0.13 μm CMOS process, the VGA, which consists of three‐stages, occupies 0.33 mm2 and dissipates 19.2 mW at 60 MHz with a supply voltage of 1.2 V. The gain range is 36.03 dB, which is controlled by a 10‐bit control word with a gain error of ±0.68 LSB.