Page 146 - The Art and Science of Analog Circuit Design

Carl Battjes

fifjiri 10-7,
1948 Experiment—
Outboarded
Distributed
Amplifier.

rates exceeded Tek's ability to manufacture. Logan left Tektronix in the early '50s
and Vollum and Rhiger were left managing this new big company. John Kobbe,
Cliff Moufton, and Bill Polits, as well as other key electrical circuit designers, took
up where Vollum, Belleville, and Rhiger had left off. Other distributed amplifiers
were designed for other 'scopes during the '50s, including the 540 series at
30MHz and the 580 series at 100MHz.

Manufacturing Distributed Amplifier Oscilloscopes

The whole idea of using a distributed amplifier as an oscilloscope vertical
amplifier is rather incredible to me. Obtaining a very fast, clean step re-
sponse is a hard job. When T-coils are employed* the job is even harder.
When they are employed wholesale, as in a distributed amplifier, they are
"fussy squared or tripled." The tuning of an oscilloscope distributed am-
plifier and/or an artificial delay line is tricky. Tuning is done in the time
domain, with clues about where and in which direction to adjust, coming
from observations of the "glitches" in the step response. If the use of a
distributed amplifier in the vertical channel of an oscilloscope was pro-
posed in today's business climate, it would be declared "unmanufactur-
able." It would never see the light of day. However, the Tektronix boom
expansion in the '50s occurred largely through the development, manu-
facture, and sale of distributed amplifier 'scopes.
The 100MHz 580 series was the last use of distributed amplifiers in
Tektronix 'scope vertical systems. Dual triodes, low cathode connection
inductance, cross-coupled capacitance neutralization, and distributed
deflectors in the CRT helped to achieve this higher bandwidth.

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