LF398S

The LF398 is a precision sample and hold amplifier which uses a combination of bipolar and junction FET transistors to provide precision, high speed, and long hold times. A typical offset voltage of 2mV and gain error of 0.004% allow this sample and hold amplifier to be used in 12-bit systems. Dynamic performance can be optimized by proper selection of the external hold capacitor. Acquisition times can be as low as 4µs for small capacitors while hold step and droop errors can be held below 0.1mV and 30µV/sec respectively when using larger capacitors. The LF398 is fixed at unity gain with 10 ohms input impedance independent of sample/hold mode. The logic inputs are high impedence differential to allow easy interfacing to any logic family without ground loop problems. A separate offset adjust pin can be used to zero the offset voltage in either the sample or hold mode. Additionally, the hold capacitor can be driven with an external signal to provide precision level shifting or "differencing" operation. The device will operate over a wide supply voltage range from ±5V to �18V with very little change in performance, and key parameters are specified over this full supply range.
Applications

• 12-Bit Data Acquisition Systems
• Ramp Generators
• Analog Switches
• Staircase Generators
• Sample and Difference Circuits