5 ms·
Surprising they didn't mention the PO74G00A and its friends. http://www.potatosemi.com/datasheet/PO74G00A.pdf http://www.potatosemi.com/datasheet/PO74G00A.pdf
by VLM 8y ago
Surprising they didn't mention the PO74G00A and its friends.
http://www.potatosemi.com/datasheet/PO74G00A.pdf http://www.potatosemi.com/datasheet/PO74G00A.pdf
Note before you try to make a 1 GHz CPU using 1970s design with those chips, for current limit reasons those chips can only switch in the GHz range with output capacitance below the input capacitance of a single gate input, so your redesigned PDP-11 is only gonna run at a mere 500 MHz not in the GHz range.
I'm a little unclear where you buy their products other than their ebay store. Digikey doesn't seem to stock. They DO seem to be real, not a meme.
I've never screwed around with the PotSemi products but I've seen the youtube videos where some dude makes a classic ring oscillator out of an inverter that runs at some high UHF frequency like seven hundred MHz or so. I thought I was pretty cool making ring oscilators running at 20-something MHz back in the 80s. If you're really bored or don't have a tape measure you can measure a length of cable by inserting it into a ring osc and recording the resulting frequency and applying some correctional math based on the speed of the inverter... I suppose with a GHz class inverter the correction factor would be round to zero for any cable longer than a couple feet and could be ignored. You can also make a toy TDR using what amounts to a ring osc and a very fast (expensive) o-scope.
Power supply noise decoupling caps must be "fun" with those chips, what happens if you put a very old 0.1 uF cap that self-resonates at a freq lower than the switching freq of the chip? Nothing good, I imagine. I know you can buy 0402 SMD caps that resonate in the higher GHz range so thats OK, but you know some goofball is going to try an 0.1 uF electrolytic for decoupling LOL.
In the "Old Days" you used strange fast high power logic sparingly to eliminate race conditions, obviously the 74F would always latch up before the 74LS or whatever so careful use of ttl family could eliminate race conditions. I would imagine that, and strange interfacing tricks, would be the purpose of modern TTL. If you wanted a slow arduino to intelligently monitor a 30 MHz signal, a little TTL support might make it possible in certain very limited cases.
- al2o3cr 8y agoThat datasheet is unclear about what exactly is required to get that 1GHz+ performance; my naive reading is that the CL=2pF case is half of another gate's input capacitance, which seems implausible. OTOH, if CMOS compatibility isn't a problem you can go waaaaay faster with things like this: https://www.analog.com/en/products/hmc746.html https://www.analog.com/en/products/hmc746.html Single gate per package, but supports 10+Gbps data rates. 290mW per gate power consumption o_O
- jacquesm 8y agoAt those frequencies an electrolytic cap is best modeled as an inductor with a parasitic capacitance ;)
- setquk 8y agoYou can do TDR (cable measurement) with 74LVC series easy enough. I built a nice little pulse generator fixture for this and use it with my Tek 475A (1.4ns risetime). Also 74AUC has Tpd of 300ps at 2.5V. I don't get why Potato even have these on the market.
- mng2 8y agoAt my work we use a COM Express module that has a Potato Semi part on it. Gotta wonder what the backstory is on that company.