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Distributed amplifier: Difference between revisions
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==Solution== | ==Solution== | ||
[[File:Distributed amplifier principle.jpg|thumb| | [[File:Distributed amplifier principle.jpg|thumb|400px|right|Distributed amplifier principle]] | ||
In a distributed amplifier, several stages are connected together to form what in effect | In a distributed amplifier, several stages are connected together to form what in effect | ||
is a "transmission line with gain". The gain is the sum (not the product) | is a "transmission line with gain". The gain is the sum (not the product) | ||
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of one stage, parasitic capacitance of that stage must not cause an impedance discontinuity | of one stage, parasitic capacitance of that stage must not cause an impedance discontinuity | ||
in the signal path, which would cause reflection. | in the signal path, which would cause reflection. | ||
[[File:Tek 581 vertical output amp.png|thumb|right|400px| [[581|Tektronix 581]] distributed vertical amplifier schematic (click to enlarge)]] | |||
Since eliminating the parasitic capacitance is not possible, the approach is usually to | Since eliminating the parasitic capacitance is not possible, the approach is usually to | ||
reduce the capacitance of the transmission line around each amplifier input (thereby | reduce the capacitance of the transmission line around each amplifier input (thereby | ||
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==History== | ==History== | ||
[[File:Tek513-dist-amp.jpg|thumb|250px|right|Symmetrical distributed amplifier in [[513]] scope]] | |||
The idea of a distributed amplifier goes back to British Patent 460,562 by W.S. Percival in 1936. | The idea of a distributed amplifier goes back to British Patent 460,562 by W.S. Percival in 1936. | ||
In 1948, Ginzton, [[Bill Hewlett|Hewlett]], Jasberg and Noe published a paper on distributed amplifiers in the Proceedings of the IRE, first using the term "distributed amplifier". Around the same time, Hewlett met [[Logan Belleville]] of Tektronix in a Portland restaurant and described the concept on a napkin. In the fall of 1948, [[Howard Vollum]] and [[Dick Rhiger]] built a 6 ns rise time distributed amplifier under a US government contract (for radar applications). The prototype was attached externally to an early [[511]] oscilloscope. | In 1948, Ginzton, [[Bill Hewlett|Hewlett]], Jasberg and Noe published a paper on distributed amplifiers in the Proceedings of the IRE, first using the term "distributed amplifier". Around the same time, Hewlett met [[Logan Belleville]] of Tektronix in a Portland restaurant and described the concept on a napkin. In the fall of 1948, [[Howard Vollum]] and [[Dick Rhiger]] built a 6 ns rise time distributed amplifier under a US government contract (for radar applications). The prototype was attached externally to an early [[511]] oscilloscope. | ||
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==Products== | ==Products== | ||
[[File: | |||
[[File:585a_dist_vert_amp.jpg|thumb|250px|right|Distributed amplifier in [[585A]] scope]] | |||
These Tektronix instruments contain distributed amplifiers: | These Tektronix instruments contain distributed amplifiers: | ||
<div style="column-count:8;-moz-column-count:8;-webkit-column-count:8"> | <div style="column-count:8;-moz-column-count:8;-webkit-column-count:8"> | ||