LF398N/NOPB (TEXAS INSTRUMENTS)

The LF398N/NOPB is a monolithic Sample-and-Hold Circuit uses BI-FET technology to obtain ultrahigh DC accuracy with fast acquisition of signal and low droop rate. Operating as unity-gain follower, DC gain accuracy is 0.002% typical and acquisition time is as low as 6µs 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 LF198-N to be included inside the feedback loop of 1MHz operational amplifiers without having stability problems. Input impedance of 10??R 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 5mV/minute with a 1µF hold capacitor. The JFETs have much lower noise than MOS devices used in previous designs and do not exhibit high temperature instabilities.