37,092
edits
No edit summary |
No edit summary |
||
(10 intermediate revisions by 3 users not shown) | |||
Line 1: | Line 1: | ||
{{Monolithic IC | |||
As a raw die, it is used in the [[H2462]] hybrid. | |Manufacturer=Tektronix | ||
|Model=M777 | |||
|Part_nos= | |||
|Description=amplifier | |||
|an=an | |||
|Used_in=H2462 | |||
|Designers=John Addis;Bob Woolhiser | |||
}}. As a raw die, it is used in the [[H2462]] hybrid. | |||
About the M777, [[John Addis]] said: | |||
<blockquote> | |||
M777 was a number I asked IC Manufacturing to reserve because | M777 was a number I asked IC Manufacturing to reserve because it was a rework of the [[M377]] using [[SHPi]] technology. | ||
it was a rework of the [[M377]] using SHPi technology. | The process name SHPi indicated it was not a significant enough update of [[SH3]] (Super High 3) to be SH4, so somewhere between SH3 and SH4 (which never happened to my knowledge). | ||
The process name SHPi indicated it was not a significant enough update of SH3 | |||
(Super High 3) to be SH4, so somewhere between SH3 and SH4 | |||
(which never happened to my knowledge). | |||
I started designing the M777 when I moved from the [[Laboratory Oscilloscopes Division]] | I started designing the M777 when I moved from the [[Laboratory Oscilloscopes Division]] to Portables Oscilloscopes (“Portables”) in April 1988, just before Lab Scopes was to be abandoned. | ||
to Portables Oscilloscopes (“Portables”) in April 1988, | |||
just before Lab Scopes was to be abandoned. | |||
The reason for this abandonment was that plugin oscilloscopes were not deemed economically competitive with portables because of the added plugin-mainframe interface requirements and mechanical complications. | The reason for this abandonment was that plugin oscilloscopes were not deemed economically competitive with portables because of the added plugin-mainframe interface requirements and mechanical complications. | ||
I heard this explanation from [[Greg Rogers]] who managed the 11K disaster. | I heard this explanation from [[Greg Rogers]] who managed the 11K disaster. | ||
Maybe it was his excuse for the 11K disaster, | Maybe it was his excuse for the 11K disaster, but it became the rationale for not doing another line of plugin scopes. | ||
but it became the rationale for not doing another line of plugin scopes. | The [[7A22]] plugin’s popularity was not enough justification for a version in the [[:Category:11000_series_scopes|11K line of instruments]], let alone in a later plugin scope family. | ||
The [[7A22]] plugin’s popularity was not enough justification for a version | Spectrum analyzers and samplers were complex enough to justify separate stand-alone instruments that already existed, but not another lab scope plugin. | ||
in the [[:Category:11000_series_scopes|11K line of instruments]], | |||
let alone in a later plugin scope family. | |||
Spectrum analyzers and samplers were complex enough | |||
to justify separate stand-alone instruments that already existed, | |||
but not another lab scope plugin. | |||
First a little history. | First a little history. | ||
The reason the M377 was designed was that the [[2465]] parts would not fit into a 4 channel 11K plugin. These parts were almost 2” by 3” because they were hybrids. | The reason the M377 was designed was that the [[2465]] parts would not fit into a 4 channel 11K plugin. These parts were almost 2” by 3” because they were hybrids. | ||
Why were they hybrids? | |||
Because Portables had not figured out how to do a | Why were they hybrids? Because Portables had not figured out how to do a DC level shift or bandwidth limiting on a monolithic chip. | ||
Portables Division did need these capabilities although the requirement was not as essential as in the 11K series. | Portables Division did need these capabilities although the requirement was not as essential as in the 11K series. | ||
7K and 11K (which was intended to use most of the 7K plugin to mainframe interface for simplicity) signals came in at | 7K and 11K (which was intended to use most of the [[7000_Series_plug-in_interface|7K plugin to mainframe interface]] for simplicity) | ||
With all NPN transistors, | signals came in at 0 V at the front panel and exited the plugins at 0 V (common mode) to the mainframe. | ||
every stage ends up at a more positive voltage output than its input. | With all NPN transistors, every stage ends up at a more positive voltage output than its input. Somehow you have to get back down to 0 V common mode. | ||
Somehow you have to get back down to | |||
7K and 11K plugins were required to enter the mainframe at | 7K and [[:Category:11000_series_plugins|11K]] plugins were required to enter the mainframe at 0 V. This was done in different ways in the 7K series. | ||
This was done in different ways in the 7K series. | |||
The [[7A11]] (1969) used PNPs at every other stage to go back and forth between +7. | The [[7A11]] (1969) used PNPs at every other stage to go back and forth between +7.1 V and –7.1 V with cascode amplifiers. | ||
The PNPs were | The PNPs were 4 GHz, and this resulted in the fastest 1 MΩ input of [[:Category:7000_series_vertical_plugins|any 7K plugin]]. | ||
[[:Category:7000_series_vertical_plugins|any 7K plugin]]. | |||
The [[7A18]] (1971) used common base PNP transistors to get back down to the | The [[7A18]] (1971) used common base PNP transistors to get back down to the 0 V common mode signal required by the main frame. The [[7A24]] and [[7A26]] later used the same technique. | ||
The [[7A24]] and [[7A26]] later used the same technique. | The 7A18 also used one of the earliest Tektronix ICs, the [[155-0022-00]] channel switch, made with the 50/450 IC process (referring to the two sheet resistivities in ohms per square used in fabricating the IC). | ||
The 7A18 also used one of the earliest Tektronix ICs, | |||
the [[155-0022-00]] channel switch, | |||
made with the 50/450 IC process | |||
(referring to the two sheet resistivities in ohms per square used in fabricating the IC). | |||
The [[7A19]] (1971) used a classic folded cascode, | The [[7A19]] (1971) used a classic folded cascode, a fast NPN common emitter transistor followed by a PNP common base transistor. | ||
a fast NPN common emitter transistor followed by a PNP common base transistor. | Here was only one stage. Trouble is, fast PNPs were only available in discrete devices, (and at that point fast NPNs were also only available | ||
Here was only one stage. | in discrete devices too, at least at Tektronix), so the amplifier was a hybrid on ceramic with a nice heat sink. | ||
Trouble is, fast PNPs were only available in discrete devices, | |||
(and at that point fast NPNs were also only available in discrete devices too, | |||
at least at Tektronix), | |||
so the amplifier was a hybrid on ceramic with a nice heat sink. | |||
It was also a simple plugin, having no Variable Gain control or BWL filter. | It was also a simple plugin, having no Variable Gain control or BWL filter. | ||
The [[485]] (1972), being a portable, | The [[485]] (1972), being a portable, could afford to allow common mode signals to climb positive with each stage. There was no level shifting. | ||
could afford to allow common mode signals to climb positive with each stage. | It was the first use of the [[M84]], later used by [[Tom Rousseau]] in the 7A26, and 7A24. | ||
There was no level shifting. | |||
It was the first use of the [[M84]] later used by Tom Rousseau in the 7A26, and 7A24. | |||
One three pole BWL filter was switched in using the other output of an M84 ([[155-0078-xx]]), and some Ls and Cs on the ECB in the main vertical amplifier. | One three pole BWL filter was switched in using the other output of an M84 ([[155-0078-xx]]), and some Ls and Cs on the ECB in the main vertical amplifier. | ||
The 7A26 (1974) used M84s (155-0078-xx), simple (SH2 IC process) amplifiers | The 7A26 (1974) used M84s (155-0078-xx), simple ([[SH2]] IC process) amplifiers whose outputs were about 3.2 V more positive than their inputs. | ||
whose outputs were about 3. | At the last stage (where drift is less important, there was a common base PNP to get back down to 0 V. | ||
At the last stage (where drift is less important, | |||
there was a common base PNP to get back down to | |||
This is a variant of what is called a folded cascode where an NPN common emitter stage drives into a PNP common base stage. | This is a variant of what is called a folded cascode where an NPN common emitter stage drives into a PNP common base stage. | ||
It’s a cascode except that the output is folded over in the middle of the cascode to make the common mode output voltage | It’s a cascode except that the output is folded over in the middle of the cascode to make the common mode output voltage 0 V. | ||
The PNP and NPN stages both get their | The PNP and NPN stages both get their DC current through a resistor to a + supply. It’s a variant because the NPN part is actually an IC (the M84). | ||
It’s a variant because the NPN part is actually an IC (the M84). | |||
The [[7A29]] (1979) used | The [[7A29]] (1979) used Zener diodes mounted on transmission lines on the ECB between stages. | ||
on the ECB between stages. | |||
The hybrids contained only metal patterns and thin film resistors, aside from the IC, so they were very simple. | The hybrids contained only metal patterns and thin film resistors, aside from the IC, so they were very simple. | ||
There was no bandwidth limit circuit, | There was no bandwidth limit circuit, as had always been the case with 50 Ω inputs. | ||
as had always been the case with | (The [[485]] had a bandwidth limit circuit, but it also had a 1 MΩ input, necessitating the BWL circuit). | ||
(The 485 had a bandwidth limit circuit, but it also had a | |||
necessitating the BWL circuit). | |||
The 2465 (1984) used Zener diodes mounted on the hybrid which also mounted the amplifier IC. | The [[2465]] (1984) used Zener diodes mounted on the hybrid which also mounted the amplifier IC. | ||
In other words, the IC did not have an on-chip level shift | In other words, the IC did not have an on-chip level shift because no one had figured out how to do that in a monolithic process. | ||
because no one had figured out how to do that in a monolithic process. | Same for the bandwidth limit, no one had figured out how to do that on a monolithic chip either, so discrete capacitors and inductors were mounted on the hybrid. | ||
Same for the bandwidth limit, | |||
no one had figured out how to do that on a monolithic chip either, | |||
so discrete capacitors and inductors were mounted on the hybrid. | |||
This and a number of thick film resistors made the hybrid quite large. | This and a number of thick film resistors made the hybrid quite large. | ||
The 11K (1987) was not possible without a new IC in the plugins capable of fitting four channels on a single plugin ECB, so the M377 was designed specifically to be small enough that four of them would fit on a single plugin ECB. Whether it was a hybrid or monolithic did not matter, it just had to be small. | The 11K (1987) was not possible without a new IC in the plugins capable of fitting four channels on a single plugin ECB, | ||
so the M377 was designed specifically to be small enough that four of them would fit on a single plugin ECB. | |||
Whether it was a hybrid or monolithic did not matter, it just had to be small. | |||
The M377 had eight major and unique innovations that allowed additional performance. | The M377 had eight major and unique innovations that allowed additional performance. | ||
# Six fixed gain settings allowing a 1 mV/div maximum sensitivity. | |||
# Capability of being wire ORd to allow multiple channel operation, eliminating a channel switch IC | |||
# On chip DC level shifting, eliminating external parts such as Zener diodes and keeping down the size | |||
# On chip bandwidth limiter (two of them, both four pole filters), keeping down the size | |||
# A really linear gain vs DC control voltage making automatic calibration and 1% calibrated gain steps possible | |||
# Elimination of adjustments for thermals in the transient response which take calibration time and board space | |||
# It was a monolithic self-contained IC, requiring no zeners, resistors, or capacitors on the ceramic | |||
# Being self contained, the M377 was tested and trimmed in wafer form, all automatically | |||
The 11K series was being abandoned starting in 1988, and along with it, the Laboratory Instruments Division. | |||
Portables management ([[John Taggart]], [[Rod Bristol]]) were aware of the M377, more so than I realized. | |||
They did need amplifiers for future portable oscilloscopes (the [[:Category:TDS_series_scopes|TDS series]]) because the 2465 parts | |||
(preamps designed by [[Jim Woo]]) were far too big and way too slow for higher speed portable scopes, which would be the only Tektronix offerings in the future. | |||
They liked the M377 because it had DC level shift, bandwidth limit filters, was monolithic and could be put in a small package. | |||
Taggart and Bristol were not about to embark on a new IC design when the M377 did everything needed for a portable scope. | |||
and | Even forgetting about the 2-3 year development time, there was nothing the M377 couldn’t do functionally and do well. | ||
They hired me to help with implementing the M377 in the [[TDS540]]. | |||
The M377 was repackaged in a 44 pin J-lead package with just a big heat sink on top and soldered onto the ECB. | |||
ECB space was even tighter than the 11K plugins, and the M377 definitely ran hotter. | |||
and | |||
I also sold another Portable Scopes group on using the M377 as it was exactly what they needed too. | |||
I believe this became the [[2245]], [[2245A]], [[2247]], [[2247A]], and [[2252]] series. | |||
Thus the M377 is used in more than just the 11K and [[:Category:TDS500_series_scopes|TDS500 series scopes]]. | |||
My principal job in Portables was to redesign the M377 with the new [[SHPi]] process. It would be known as the M777. | |||
My principal job was to redesign the M377 with the new SHPi process. | |||
It would be known as the M777. | |||
[[Bob Woolhiser]] left Tek’s excellent CAD group and worked with me to implement the M777. | [[Bob Woolhiser]] left Tek’s excellent CAD group and worked with me to implement the M777. | ||
I left Tektronix before the M777 was finished, | I left Tektronix in April 1991 before the M777 was finished, but it was in capable hands. | ||
but it was in capable hands. | |||
Woolhiser had responsibility for the M777. | Woolhiser had responsibility for the M777. | ||
Woolhiser implemented the 250 MHz BWL filter in place of the 100 MHz BWL filter in the M377. | |||
He too moved on and [[Rich Huard]] finished the M777. | |||
The M777 is bond pad compatible in every way with the M377, but faster. | The M777 is bond pad compatible in every way with the M377, but faster. | ||
And because of the extra bandwidth, it was also a little noisier. | And because of the extra bandwidth, it was also a little noisier. | ||
The M377 had a long life, | The M377 had a long life, still in production after [[Maxim|Maxim Integrated]] bought the Tektronix IC facility ([[Building 59]]). | ||
still in production after Maxim Integrated bought the Tektronix IC facility (Building 59). | Part of the purchase agreement was support for the Tektronix IC processes, including [[SH3]], [[SHPi]] (that included p-channel JFETs), | ||
Part of the purchase | and [[CPi]] (included high speed complementary PNPs). I cannot speak with authority about these later years. | ||
including SH3, SHPi (included | |||
and | There was a chip that included the input IC for the TDS540 series that [[Art Metz]] originated and I adapted using the p-channel JFETs. | ||
I cannot speak with authority about these later years. | Eventually, I believe, the two chips were combined into a new IC based on both these designs, although I am not sure of this. | ||
However, I believe the M377 and M777 continued in production until Maxim stopped. | |||
There was | There was some friction between Maxim and Tektronix as Maxim was bound by contract to supply legacy parts. | ||
Eventually (about 1997) the Tektronix processes went out of production. | |||
Eventually | </blockquote> | ||
[[Category:Tektronix-made monolithic integrated circuits]] | [[Category:Tektronix-made monolithic integrated circuits]] |