Asianometry does a pretty good job here. I am sure people will quibble about some of his descriptions of radio, AF, and RF. But overall, pretty good. I did see what looked like a direct conversion receiver in his block diagrams, but it was described as a superhet.
I was also struck by what looked like the lack of shielding in the modern cell phones. Some hams seem to believe that we cannot live without shielding. But apparently we can.
I also like how the bloc diagrams have the LO feeding mixers both on the receiver side and on the transmit side. I realize that you can do this by switching the LO, but I like to feed both mixers at the same time.
Asianometry talks about the need for inductors in the chips, and how this was often a show-stopper. This made me think about the Gilbert Cell that we find in our beloved NE-602s. Wasn't Barry Gilbert trying to create a balanced mixer that would not need coils?
Finally, there is a nice review of the history of Silicon Labs. I was hoping to see the Si570 and, of course, the Si5351. But no, these seem to have come later than the slide used by Asianometry.
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As I watched Jon's video just as it was released, I thought you'd enjoy it too. The apparent lack of shielding isn't what it seems in MMIC's. The order of the day is to obtain adequate isolation between sections as necessary. The need for shielding has been reduced by the small dimensions of the inductors, primarily, as these are at GHz frequencies. And providing that isolation is also done in other clever ways, like orientation of components.
ReplyDeleteThe Gilbert cell can be done without transformers or inductors, depends upon what level of performance you are looking for. No free lunch.
Mike: Thanks. I don't think they have any inductors in the NE602. I may be wrong. I thought the desire to avoid coils was one of the things that drove Barry Gilbert. 73 Bill
ReplyDeleteNot sure what his motivation was, but it performs the mixing function well. Used them in different forms. Lately, the Spectrum Analyzer project has been using LTC5562's. Pricey, covers LF-7GHz and has great intermod. It likes to be fed balanced for best performance. But its so overkill for Homebrew DCR's at HF, though! Diode DBM's are a great fit for that.
ReplyDeleteThe NE/SA 602/612's are history. Good to see MC1496's still active.
I love any video that shows the insides of microelectronics. Until he retired in the early 1980s, my Dad was a manufacturing and process engineer in aerospace electronics. The smallest things he made were thick-film resistor arrays for precision ADCs--maybe 1/4" square. These days, you can put an entire MCU and several GBs of memory on a chip that size.
ReplyDeleteBTW, not long ago I had to get a new cell phone, so out of curiosity I completely dismantled the old one. There's actually RF shielding all over the place. For instance, the entire back of the LCD panel was a single sheet of copper foil, pretty-much shielding one whole face of the device. There were patches of copper mesh embedded in the plastic in various places, and spring contacts connecting them with patches of conducting paint applied directly to plastic. There was also foil and plastic laminates applied over various (no-doubt sensitive) parts of the motherboard, connected together with narrow traces of foil. The multilayer motherboard itself contains internal ground planes that shield each side of the board from the other. Cell phones aren't just marvels of electronics, they're also marvels of manufacturing. They're kinda like automobiles in that regard: they're feats of coordinated engineering management. Some of that engineering goes into meeting and passing strict EMI and RFI requirements of the FCC and the CE (Conformitè Europëenne--it doesn't mean "China Export" as some think).
Good video. Enjoyed the history and details of the device construction.
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