26A2 Differential Amplifier
100 to 100,000 gain
DC to 1 MHz Bandwidth at all Gain settings
The 26A2 is a DC-coupled differential amplifier designed for use in the 2600-Series modular instrument
system. Excellent common-mode rejection, high gain, and selectable high- and low-frequency -3 dB points,
make the 26A2 suitable for low-frequency, low-level applications.
There are many factors which affect the usability of high-gain, wideband differential amplifiers.
Noise (if excessive) can make the high-gain positions unusable. Since noise is related to bandwidth, noise
can be greatly reduced with a HF -3DB POINT selector when the applicaion allows. DC drift can also hinder
measurements causing the trace to move offscreen rapidly. A small signal DC component, perhaps a few millivolts,
would also place a DC-coupled display offscreen at 10 μV/div. There are three ways to reject this DC voltage:
(1) AC coupling the input if the signal frequency is high enough to be unaffected (2 Hz, LOWER -3dB POINT).
(2) AC coupling with the LF -3 DB POINT selector which allows lower bandwidth selection down to 0.1 Hz.
(3) DC OFFSET which supplies an internal DC voltage to offset, or reject, the DC signal component.
A guard signal derived from the common-mode signal within the amplifier is available on the front panel for
driving cable shields. ± 15 volts DC is also available to permit use of special active probes,
transducer adapters, etc.