282

From TekWiki
Jump to navigation Jump to search
Tektronix 282
Unity gain buffer
Tektronix Type 282

Produced from 1966 to (?)

Manuals
(All files in PDF format unless noted otherwise)
Manuals – Specifications – Links – Pictures

The Tektronix Type 282 is an active adapter introduced in 1966 that allows high-impedance probes to be used with instruments that have 50 Ω inputs.

It is a unity-gain buffer withan input impedance of 1 MΩ in parallel with 16.5 pF and a low output impedance.

The high-impedance input stage is a dual-JFET where transistor A operates as a source-follower and transistor B operates as a current source biased with Vgs = 0, maintaining a constant (Idss) current through transistor A, independent of input signal voltage. After the FET input stage, the signal is fed to a Sziklai pair formed of a PNP transistor first, driving an NPN output transistor. The Sziklai pair is non-inverting and has a voltage gain greater than unity, which allows the overall gain of the 282 to be trimmed for exactly unity gain. The rise time is 3 ns when driven from a 25 Ω source.

This active adapter is powered over 1S1, 3S1 and 3S76.

Pictures