LF198

Philips Semiconductors Linear Products Product specification Sample-and-hold amplifiers LF198/LF298/LF398 DESCRIPTION The LF198/LF298/LF398 are monolithic sample-and-hold circuits which utilize high-voltage ion-implant JFET technology to obtain ultra-high 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 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 to be included inside the feedback loop of 1MHz op amps without having stability problems. Input impedance of 1010Ω 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/min 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. The overall design guarantees no feedthrough from input to output in the hold mode even for input signals equal to the supply voltages. Logic inputs are fully differential with low input current, allowing direct connection to TTL, PMOS, and CMOS; differential threshold is 1.4V. The LF198/LF298/LF398 will operate from ±5V to ±18V supplies. They are available in 8-pin plastic DIP, 8-pin C...