[HN Gopher] Rohde and Schwarz AMIQ Modulation Generator Teardown
___________________________________________________________________
Rohde and Schwarz AMIQ Modulation Generator Teardown
Author : iamsrp
Score : 42 points
Date : 2025-06-08 14:51 UTC (3 days ago)
(HTM) web link (tomverbeure.github.io)
(TXT) w3m dump (tomverbeure.github.io)
| CamperBob2 wrote:
| Great disassembly job. There's yet another branch of the rabbit
| hole that Tom almost fell down: ... the
| multiplier is based on a classic form, having a
| translinear core, supported by three (X, Y, and Z)
| linearized voltage-to-current converters, and the load
| driving output amplifier. I have no clue how the thing
| works!
|
| The 'translinear' school of design was founded (or at least
| popularized) by Barrie Gilbert at Analog Devices
| (https://en.wikipedia.org/wiki/Translinear_circuit ,
| https://en.wikipedia.org/wiki/Barrie_Gilbert ). Gilbert was one
| of the undisputed GOATs in the analog field and a full-fledged
| Renaissance man in his own right. It's worth reading more about
| him if/when you have the time and inclination.
| KK7NIL wrote:
| Gilbert was a legend of analog design.
|
| Here's a lecture by him on the translinear principle:
| https://youtu.be/LQNJVtcFrCc
|
| And here's some history of his work at Tektronix (where he
| discovered the translinear principle):
| https://vintagetek.org/barrie-gilbert/
| tverbeure wrote:
| That's for that info! I'll give that links a good read.
| blantonl wrote:
| Some of this obscure test equipment is very interesting and
| amazingly designed.
|
| There are probably only a few electrical engineers in the entire
| world that actually use this stuff on a day to day basis.
| jandrese wrote:
| R&S equipment is pretty common in the cellular industry. There
| is more of it out there than you would think. While this
| particular signal generator is maybe not the most common piece
| of equipment you will see lots of R&S spectrum analyzers and
| the like.
| Junk_Collector wrote:
| It's technically not a signal generator but an Arbitrary
| Waveform Generator. It provides a base-band modulated signal
| to the signal generator which the sig gen upconverts to the
| RF carrier. If you purchased a Vector Signal Generator this
| would be built in but you can still buy them stand alone and
| they are pretty common. NI, R&S, Tek, and Keysight all have
| product lines of them.
|
| Another way to think about it, this would be comparable to a
| signal generator in the same way that an oscilloscope is
| comparable to a spectrum analyzer.
| tverbeure wrote:
| What you call a signal generator is what most would call an
| RF signal generator. Both an AWG and an RF signal generator
| belong to the generic signal generator family. :-)
| raziel2701 wrote:
| Does anyone know what company auctions this stuff? The author
| doesn't say.
| avidiax wrote:
| I had the same question. Seems the UC schools use
| Publicsurplus.com, but last time I looked, I didn't see
| anything interesting.
| tverbeure wrote:
| I bought it through edispositions.com.
|
| Extremely good deals are rare and the chance that there's
| something broken is very real. I often consider that a
| feature: fixing test equipment is a bit of a hobby, but be
| prepared to end up with a doorstop that cost a few hundred
| dollars.
|
| Here are some examples that I bought though them:
|
| - HP 8650E spectrum analyzer: works but intermittent
| shutdowns
|
| - TDS 794D: works, but CRT is broken. A well know failure
| mode. Need to install a $75 LCD replacement.
|
| - this R&S AMIQ: totally broken. Needed many days of work to
| revive.
|
| It's high risk buying these things.
| myself248 wrote:
| You'll find whole labs full of it once in a while on
| Bidspotter, set a saved-search for some names like Rohde and
| Tektronix and Keysight and you'll get emails once in a while.
| leoh wrote:
| ELI5: what is this used for?
| tverbeure wrote:
| It's used to create communication test signals.
|
| Say you designed a Bluetooth transceiver chip and need to test
| the performance under stress conditions: noise, sample clock
| instability etc.
|
| The WinIQSim software simulates such a signal and uploads it to
| the AMIQ, which is essentially a high quality digital analog
| converter.
|
| The analog output will go to an RF signal generator and then to
| your chip under test.
| myself248 wrote:
| I'm amused that it's just a PC motherboard, and that it uses ISA
| to talk to the generator hardware itself. Makes perfect sense;
| nothing needs high data rates there, and it's really easy to
| interface with. I just wouldn't have necessarily predicted it
| before seeing the case open.
___________________________________________________________________
(page generated 2025-06-11 23:01 UTC)