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The Tektronix M084  (P/N 155-0078-xx,155-0273-00,155-0274-00) is a broadband amplifier monolithic integrated circuit in a minipac package. The input and output are differential. The 155-0078 and its test fixture were designed by John Addis for the 485 scope (Note 1), which uses no less than 18 of these chips in various grades.

The last two digits of the part number, the grade, correspond to a combination of DC and HF performance. Each M84 was tested for DC performance and HF performance. DC performance was tested using a custom fixture described below. HF performance was tested using the 25ps Push-Pull Pulse Generator.

The last two digits of the 155-0078-xx part number are determined by a selection process after manufacture:
Suffix Speed DC Charact. Replaceable by
00 Fast Best ----
01 Fast Third best -03,-00
02 Fast Most relaxed -01,-03,-00
03 Fast Second best -00
04 Slow Same as -00 -00
05 Slow Same as -01 -03,-00,-07,-04
06 Slow Same as -02 -01,-03,-00,-05,-07,-04
07 Slow Same as -03 -00,-04
10 Fast Best ----
11 Fast Third best -13,-10
12 Fast Most relaxed -11,-13,-10
13 Fast Second best -10
Sometimes an instrument will contain a better grade of part than called for in the manual.

The manual should be consulted for the correct replacement type.

The M84 also comes in 14-pin DIP, as 155-0273-00 and 155-0274-00 (slower grade).

Regarding the various grades of M84, John Addis says:

There are several DC specs which differ with part suffix.

Suffixes -10, -11, -12 and -13 were used for the redesigned M84, known as the M705. The M705 was necessary because the original SH2 (2-2.5 GHz?) process was being discontinued. The M705 was designed by Hal Lillywhite using the faster SH3 process (6-7 GHz). Additionally, the M705 apparently had the gain setting resistor laser trimmed at the wafer level. The M705 was designed in late 1989 and tested in early 1990.

There was one high frequency test fixture and perhaps two dc test fixtures. Every M84 was subjected to all tests. All tests were done manually. I designed both test fixtures and the 25ps PPPG.

Transient Response (schematic not shown) uses the 25ps Push Pull Pulse Generator (PPPG) and a sampling scope. Sampler load supplies dc current (through X2 pads and sampler input resistance. The sampling scope chassis is floating at (probably) +5V through 8.2 ohms. 25ps PPPG has transformer coupled trigger output to sampling scope trigger input.

DC test fixture:

I have attached a schematic of a dc test fixture for manufacturing. It looks like this fixture only tests for Vhump. There may have been another test fixture for the other dc tests. Those tests may have been done on a system. The Vhump test may have been so difficult to perform on an automated system that it needed this extra fixture.

Vhump is the amount of maximum dc imbalance, probably referred to the input, which occurs when the variable gain function is swept from full invert to full normal. The two ends of the curve are set to the same dc output level using the balance control attached to pin 1. Ideally, there is no change in dc level under these conditions, but various imbalances in the M84 output devices result in a hump for inverted gain and a hump for the normal gain. Only the -00, -04 and -10 suffixed parts were required to pass this stringent Vhump test. The fixture was in a rubber footed metal chassis about 4” high 5” deep, and 7” wide.

Test criteria defining the various grades of M84:
Displayed Risetime <355 ps -00 and -10 -01 and -11 -02 and -12 -03 and -13
Displayed Risetime 355-410 ps -04 -05 -06 -07
Normal Offset (RTO) <14 mV <14 mV <28 mV <14 mV
Invert Offset (RTO) <14 mV <14 mV <28 mV <14 mV
HFE of Q1 and Q2 70-250 70-250 50-400 70-250
Normal Gain 2.68-2.96 2.68-2.96 2.68-2.96 2.68-2.96
Invert Gain 2.68-2.96 2.68-2.96 2.68-2.96 2.68-2.96
Null Offset (Gain = 0) 10 mV no spec no spec <30 mV
Null Gain (Test of Q3 and Q4) 14 mV no spec no spec <14 mV
50% Gain 0.49-0.51 no spec no spec 0.49-0.51
Off Feedthrough <0.2 mV <0.2 mV <0.2 mV <0.2 mV
Normal Hump Voltage <2.5 mV no spec no spec no spec
Invert Hump Voltage <2.5 mV no spec no spec no spec

See also


Used in

Some instruments using part 155-0078-00

Instrument Manufacturer Class Model Description Introduced
067-0587-01 Tektronix Plug-in 067-0587-01 7000 Series Calibration Fixture (?)
067-0680-00 Tektronix Plug-in 067-0680-00 5400 Series Mainframe Calibrator (?)
464 Tektronix Oscilloscope 464 Portable 100 MHz dual-trace storage scope 1975
465 Tektronix Oscilloscope 465 Portable 100 MHz dual-trace scope 1972
466 Tektronix Oscilloscope 466 Portable 100 MHz dual-trace storage scope 1974
468 Tektronix Oscilloscope 468 10/100 MHz Digital Storage Scope 1980
475 Tektronix Oscilloscope 475 Portable 200 MHz dual-trace scope 1972
475A Tektronix Oscilloscope 475A Portable 250 MHz dual-trace scope 1977
485 Tektronix Oscilloscope 485 350 MHz portable scope 1972
7104 Tektronix Oscilloscope 7104 1 GHz mainframe with MCP CRT 1978
7834 Tektronix Oscilloscope 7834 400 MHz storage mainframe 1977
7844 Tektronix Oscilloscope 7844 400 MHz dual-beam non-storage mainframe 1974
7854 Tektronix Oscilloscope 7854 400 MHz waveform-processing scope 1980
7904 Tektronix Oscilloscope 7904 500 MHz non-storage mainframe 1971
7912AD Tektronix Oscilloscope 7912AD 500 MHz digitizer 1978
7912HB Tektronix Oscilloscope 7912HB 750 MHz digitizer 1988
7A16A Tektronix Plug-in 7A16A 225 MHz vertical amplifier 1973
7A16P Tektronix Plug-in 7A16P 150/200 MHz vertical amplifier 1978
7A24 Tektronix Plug-in 7A24 400 MHz dual channel vertical amplifier 1974
7A26 Tektronix Plug-in 7A26 200 MHz dual-channel amplifier 1974
7A42 Tektronix Plug-in 7A42 350 MHz four-channel logic triggered amplifier 1984
AM503 Tektronix Plug-in AM503 current probe amplifier 1976
DC5010 Tektronix Plug-in DC5010 350 MHz programmable frequency counter 1982
DC510 Tektronix Plug-in DC510 350 MHz frequency counter 1982
FG5010 Tektronix Plug-in FG5010 20 MHz function generator 1982
PG502 Tektronix Plug-in PG502 250 MHz pulse generator 1974
PG508 Tektronix Plug-in PG508 50 MHz pulse generator 1976
R7903 Tektronix Oscilloscope R7903 500 MHz non-storage mainframe 1974
R7912 Tektronix Oscilloscope R7912 500 MHz digitizer 1973


  • Note 1: See John Addis quote in 7A11 article