Amplifiers for high-speed current-mode sample-and-hold circuits

The speed of most current-mode analog circuits is limited by the performance of the sample-and-hold operation. By using a transimpedance amplifier, instead of the more usual voltage amplifier in the sample-and-hold, it is shown that an order of magnitude increase in speed can be achieved without increasing the chip area or the DC power consumption. The technique has been used in a current-mode sample-and-hold designed to provide 12-b linearity at sampling rates of up to 10 MHz with a power consumption of under 5 mW using a 1.2-μm CMOS process