Talk:Barrie Gilbert

Jones Invention Used for Communications

I have undid the revert that a misguided editor has made to the correct account of R.F mixers in main stream products. Unfortunately, some editors are either insufficiently knowledgeable on electronic design and use, or unable to do a Google search for "Gilbert Cell" + "Schematic". Nor are they willing or able to cite references that would support their view. Such a search will clearly, and indisputable show that the topology known as the "Gilbert Cell", and essentially, universally used as an R.F. Mixer is the topology invented by Howard Jones. Gilbert's invention requires the use of logging diodes that are clearly absent in the vast majority of R.F mixers. The references clearly demonstrate such a position. To editors, please do not revert without citing sources to verify your particular illusion of the facts. Kevin Aylward 17:29, 16 May 2014 (UTC)

Jones invented the "Gilbert" Cell

I have reverted back to the correct account of the Gilbert Cell and its use in communication equipment. There appears to be a misunderstanding here. The reason given for reverting my text was "Jones patent is switching demodulator rather than translinear" was not relevant. This was a actually a classic Strawman argument. There is no disagreement on this point. Jones did not invent the Translinear concept, but he did invent the cross coupled cascode differential pair that is used in the billions of communication systems, which is unfortunately, usually referred to as a "Gilbert Cell". Gilbert invented a two diode addition to the Jones Cell which is used when high linearity is required. Gilberts translinear variant of the Jones Cell is, essentially, never used in R.F.Mixers. This is easily confirmed by googling "Gilbert cell" "Schematic". Pretty much invariably, what will be shown is the same cell as that in the Jones patent, without the Gilbert added diodes. Gilbert himself tried to correct this misunderstanding, but failed. This is shown in the paper http://users.ece.gatech.edu/~rincon/classes/ana_history.pdf page 46. To wit: "When it comes to mixers (or multipliers), almost every communications engineer immediately thinks of the “Gilbert cell” or “Gilbert mixer.” However most textbooks,and a great many journal and conference papers, actually describe an earlier invention by Howard E. Jones, instead of Barrie Gilbert’s superficially similar multiplier(see Figures 11 and 12) [17][18]." Kevin Aylward 16:45, 30 April 2014 (UTC) — Preceding unsigned comment added by Kevin aylward (talk • contribs)

The Gilbert multiplier is not a switch

Added Note by Keith Lofstrom, Barrie Gilbert wannabee at Tektronix

The Gilbert multiplier cell does indeed use two matched pairs of transistors, but they are not merely switched discretes on circuit boards, as described in the Jones patent. Paired switches weren't new when Jones wrote his patent - similar circuits using vacuum tubes anticipated the Jones patent by decades, and some were used in pre-transistor Tektronix oscilloscopes for switching between vertical amplifier channels.

Barrie's translinear insight was that if the transistor pairs were operated in the trans-linear region (not switched!) and drove similar translinear transistor-junction amplifiers, then a current-to-current multiplication was achieved - you could multiply two sine waves together and generate the sum and difference frequencies with low harmonics. Very important, since in those days you could not put a cheap high Q precision frequency filter on a chip (now we can - laser-trimmed SAW resonators are chip-sized and made by the billions). A current-fed multiplier detector using a Gilbert-style translinear detector can be followed by a simple low-pass filter, or directly feed a sampling digitizer.

A translinear circuit such as a Gilbert gain cell requires well-matched transistors, all on the same integrated circuit chip in practice, which is why Tektronix manufactured bipolar integrated circuits internally, and why Tek employed world-class integrated circuit visionaries like Barrie, and wannabees like me.

I'd be tempted to throw out the entire section about the Jones switch, which is not a Gilbert gain cell, but I will leave that edit war to seasoned wikipedians. — Preceding unsigned comment added by KeithLofstrom (talk • contribs) 01:18, 30 January 2021 (UTC)

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