155-0032-00: Difference between revisions
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It is packaged in a 16-pin DIP. | It is packaged in a 16-pin DIP. | ||
Regarding the 155-0032-xx, John Addis says, | Regarding the 155-0032-xx, [[John Addis]] says, | ||
<blockquote> | <blockquote> | ||
The 155-0032-00’s IC process had an FT of 1.0 or 1. | <p>The 155-0032-00’s IC process had an FT of 1.0 or 1.2 GHz (don’t remember), rather inadequate for the job. | ||
The on-chip resistors were diffused and thus had | The on-chip resistors were diffused and thus had too poor a TC and tolerance for use as gain-setting resistors. | ||
too poor a TC and tolerance for use as gain-setting resistors. | </p> | ||
< | <p> | ||
< | As you can see, there are two separate gain selections determined by which set of emitters is chosen, pins 1 and 16 or 2 and 15. | ||
As you can see, | |||
there are two separate gain selections determined by which set of emitters is chosen, pins 1 and 16 or 2 and 15. | |||
This selection is made off chip by choosing Q205 or Q215 to carry the current through R212. | This selection is made off chip by choosing Q205 or Q215 to carry the current through R212. | ||
Pot R217 allows dc balance at 5mV/div to match that at all other sensitivities, controlled elsewhere. | Pot R217 allows dc balance at 5mV/div to match that at all other sensitivities, controlled elsewhere. | ||
< | </p> | ||
< | <p> | ||
Pin 12 ultimately selects which pair of the four output cross-connected transistors passes | Pin 12 ultimately selects which pair of the four output cross-connected transistors passes | ||
the signal current from the two transistors whose bases are connected to pin 4. | the signal current from the two transistors whose bases are connected to pin 4. | ||
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This same pair of transistors also enables variable gain by allowing | This same pair of transistors also enables variable gain by allowing | ||
a controlled amount of cross-coupling of the signal. | a controlled amount of cross-coupling of the signal. | ||
< | </p> | ||
< | <p> | ||
This is an undesirable way of doing variable gain control, but neither Roy nor I knew that at the time. | This is an undesirable way of doing variable gain control, but neither Roy nor I knew that at the time. | ||
It is a noisy configuration. At the 0% signal gain there is lots of noise gain. | It is a noisy configuration. At the 0% signal gain there is lots of noise gain. | ||
It has poor thermal balance at anything other than 100% and the not very useful 0% signal gain. | It has poor thermal balance at anything other than 100% and the not very useful 0% signal gain. | ||
In between 0% and 100% gain, the circuit is poor in noise and thermal balance. | In between 0% and 100% gain, the circuit is poor in noise and thermal balance. | ||
I went on to use the same (Gilbert Multiplier) circuit in the 155-0078-xx (M84) and | I went on to use the same (Gilbert Multiplier) circuit in the [[155-0078-00|155-0078-xx (M84)]] and | ||
made the same bad choice again in the 7A29. | made the same bad choice again in the [[7A29]]. | ||
In our defense, with just two stages and the need to do both invert and variable gain control somewhere, there was not a lot of choice. | In our defense, with just two stages and the need to do both invert and variable gain control somewhere, there was not a lot of choice. | ||
< | </p> | ||
< | <p> | ||
It was not until I designed the M377 for the 11000 series of plugins (11A32, 11A33, 11A34, 11A52) that I finally got it right. | It was not until I designed the [[M377]] for the 11000 series of plugins ([[11A32]], [[11A33]], [[11A34]], [[11A52]]) that I finally got it right. | ||
(See the British magazine Electronic Engineering, September, 1988, pp 40-41.) | (See the British magazine Electronic Engineering, September, 1988, pp 40-41.) | ||
< | </p> | ||
< | <p> | ||
The M377 was a single channel plugin on a chip with 0V common mode input and output voltages, | The M377 was a single channel plugin on a chip with 0V common mode input and output voltages, | ||
excellent variable gain control, two four pole bandwidth limits, | excellent variable gain control, two four pole bandwidth limits, | ||
three outputs which could be separately inverted and turned on or off. | three outputs which could be separately inverted and turned on or off. | ||
< | </p> | ||
< | <p> | ||
It was the first wideband analog IC with level shift on chip (allowing 0V common mode input and output and without PNP transistors), | It was the first wideband analog IC with level shift on chip (allowing 0V common mode input and output and without PNP transistors), | ||
first wideband amplifier with any on-chip bandwidth limit selection, first to have more than two fixed gain settings (it has six), | first wideband amplifier with any on-chip bandwidth limit selection, first to have more than two fixed gain settings (it has six), | ||
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and the first to have a highly linear relationship between a control voltage and gain. | and the first to have a highly linear relationship between a control voltage and gain. | ||
It also had excellent overdrive recovery. Live and learn. | It also had excellent overdrive recovery. Live and learn. | ||
</p> | |||
</blockquote> | </blockquote> | ||
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<gallery> | <gallery> | ||
155-0032-00.png|Block diagram | |||
155-0032-XX in 7A12.jpg|155-0032-00 schematic shown in the 7A12 schematic | 155-0032-XX in 7A12.jpg|155-0032-00 schematic shown in the 7A12 schematic | ||
</gallery> | </gallery> | ||
[[Category:Tektronix-made integrated circuits]] | [[Category:Tektronix-made integrated circuits]] |