he LF398 devices are monolithic sample-and-hold circuits that use BI-FET technology to obtain ultrahigh DC accuracy with fast acquisition of signal and low droop rate. Operating as a unity-gain follower, DC gain accuracy is 0.002% typical and acquisition time is as low as 6 ?s to 0.01%. A bipolar input stage is used to achieve low offset voltage and wide bandwidth. Input offset adjust is accomplished with a single pin and does not degrade input offset drift. The wide bandwidth allows the LF398 to be included inside the feedback loop of 1-MHz operational amplifiers without having stability problems. Input impedance of 1010 ? allows high-source impedances to be used without degrading accuracy. P-channel junction FETs are combined with bipolar devices in the output amplifier to give droop rates as low as 5 mV/min with a 1-?F hold capacitor.
