GENERAL DESCRIPTION

The AD8244 is a precision, low power, FET input, quad unity-gain buffer that is designed to isolate very large source impedances from the rest of the signal chain. The 2 pA maximum bias current, near zero current noise, and 10 TΩ input impedance introduce almost no error, even with source impedance well into the megaohms.

FEATURES

Low power

250 µA maximum supply current per amplifier

FET input

2 pA maximum input bias current at 25°C

Extremely high input impedance

Low noise

13 nV/√Hz voltage noise at 1 kHz

0.4 µV p-p voltage noise (0.1 Hz to 10 Hz)

0.8 fA/√Hz current noise at 1 kHz

High dc precision

3 µV/°C maximum offset drift (B grade)

3 MHz bandwidth

Unique pinout

No leakage from inputs to supply pins

Provides guarding capability

Rail-to-rail output

Single-supply operation

Input range extends to ground

Wide supply range

Single-supply: 3 V to 36 V

Dual-supply: ±1.5 V to ±18 V

Available in a compact 10-lead MSOP

APPLICATIONS

Biopotential electrodes

Medical instrumentation

High impedance sensor conditioning

Filters

Photodiode amplifiers