LF398N Description

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 101?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.
LF398N Features

Low input offset
Low output noise in hold mode
Input characteristics do not change during hold mode
High supply rejection ratio in sample or hold
Wide bandwidth
LF398N Applications

Ramp Generators With Variable Reset Level
Integrators With Programmable Reset Level
Synchronous Correlators
2-Channel Switches
DC and AC Zeroing
Staircase Generators