Datasheet

TL087, TL088, TL287, TL288
JFET-INPUT OPERATIONAL AMPLIFIERS
SLOS082B – MARCH 1979 – REVISED – JULY 2004
6
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
typical values
Typical values as presented in this data sheet represent the median (50% point) of device parametric
performance.
input bias and offset current
At the picoamp bias current level typical of these JFET operational amplifiers, accurate measurement of the bias
current becomes difficult. Not only does this measurement require a picoammeter, but test socket leakages can
easily exceed the actual device bias currents. To accurately measure these small currents, Texas Instruments
uses a two-step process. The socket leakage is measured using picoammeters with bias voltages applied, but
with no device in the socket. The device then is inserted in the socket and a second test that measures both
the socket leakage and the device input bias current is performed. The two measurements then are subtracted
algebraically to determine the bias current of the device.