Gateless Majority Logic

KD5ZXG

Gawd
Joined
Mar 24, 2017
Messages
586
What it might look like if we chain 8 bits together for a full result...
Replacing two earlier drawings in this same post that had errors.

Fix20200918.png


Trying here to make better sense of several earlier messes.
Changed "Inhibit" to "Kill" cause "I" looked too much like "1".
Changed "CarryIn" to "EQ" cause it made better sense of the new comparator functions.
"C" never made sense for Borrow, especially since I don't get there by add with inversions.
Selection of conditional logic now hijacks Carry rather than Borrow, cause it drew easier.
Four bits might fit a module of 32 pins with power and /OE, if I were to build it...
 
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KD5ZXG

Gawd
Joined
Mar 24, 2017
Messages
586
The ALU above merits a barrel shifter.

Barrel.png


Since switches can all be thrown while the ALU churns, the only delay is propagation through two transmission gates. 250pS each...

Note that only 6 devices are needed. Not requiring the braindead obvious 8 multiplexers, each sweeping through 8 steps of rotation.
Also consider the parasitic spaghetti factor. Only four dead-ends splay out per bit, instead of the expected seven. Expand to 16bits,
the low row of plexers would then become 4way as well. 6 dead-end sphaghetti vs 15 the dumb way.

The best way might be seriously wasteful of devices. Full spread from results to intermediate sphagettiland with no shared strand.
Then a full scrunch to rotated results. Why? Because unused strands cut from both ends cease to present unterminated stubs.
You might be surprised how much problem an unexpected inch long echo can cause...
 
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KD5ZXG

Gawd
Joined
Mar 24, 2017
Messages
586
The offical name for these sort of switches would be "Transmission Gate". Below are
several common ways you might see them drawn in multiplexer spec sheets. Doesn't
seem to be much of an agreed standard across brands.

I was drawing them as-if relays. Overuse of that symbol ate too much space in my
drawings. Lately I'm drawing an abstract trapezoid to stand for a multiplex of several.
Somtimes I still prefer to draw finer details to explain some point or other.

Body diode given in the symbol for a stand-alone MOSFET would cause directional
leakage issues in a transmission gate. Fortunately, diodes in this situation connect
only to rails, not immediately to each source. MOS4 symbols I needed were already
in LTSpice. Just had to discover them.

TransmissionGates2.png


All gates are driven by internal pre-amps. Some amps offer protection features.
I didn't bother to draw all those amps, except the one case with a charge pump.
Just know they are there, and differ, and read your spec sheet before choosing.

Main gotchas to watch for:
74CBT needs VCC to be 2V higher than any signal you might want to pass.
74CB3Q has a charge pump, but power limited to 10 or 20 MegaSwitches/Sec.
74CBTLV can pass signals rail to rail, but PMOS isn't quite as fast as NMOS.
 
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KD5ZXG

Gawd
Joined
Mar 24, 2017
Messages
586
Always troubleshooting someone else's board, never designing my own...

I need some layout software with minimal learning curve that can handle 2 layers and SSOP16.
The place I work for uses Altium. But its overkill, and the licence fee is rather extreme. Plus they
don't want me hanging around off the clock to use a company PC with an existing licence.

So I will probably try: What is free tier Altium called, Circuit Maker? I gather you are forced to
openly publish your projects. And thats probably to prevent commercial misuse. Dunno what
other limitations. If its way different than regular Altium, the guys at work may not be able to
help me. Ultimately I need Gerber compatible files to have a board made...

The alternative is a crapload of 50cent DIP adapters and Vero Board. Which will get me there,
but isn't reproducible if I want to expand. And parasitic sphagetti might slow things more than
prove anything fast.
 
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Joined
May 5, 2013
Messages
34
Always troubleshooting someone else's board, never designing my own...

I need some layout software with minimal learning curve that can handle 2 layers and SSOP16.
The place I work for uses Altium. But its overkill, and the licence fee is rather extreme. Plus they
don't want me hanging around off the clock to use a company PC with an existing licence.

So I will probably try: What is free tier Altium called, Circuit Maker? I gather you are forced to
openly publish your projects. And thats probably to prevent commercial misuse. Dunno what
other limitations. If its way different than regular Altium, the guys at work may not be able to
help me. Ultimately I need Gerber compatible files to have a board made...

The alternative is a crapload of 50cent DIP adapters and Vero Board. Which will get me there,
but isn't reproducible if I want to expand. And parasitic sphagetti might slow things more than
prove anything fast.
KiCad?
 

KD5ZXG

Gawd
Joined
Mar 24, 2017
Messages
586
https://www.sciencemag.org/news/2020/09/short-weird-life-and-potential-afterlife-quantum-radar

"real entangled light pulses that experimenters can generate with a special crystal that converts a single higher frequency pulse to two entangled pulses at lower frequencies."
"Physicists can generate pairs of entangled microwave pulses from single ones using, instead of a crystal, a gizmo called a Josephson parametric converter."

Science news oversimplified to the point of nonsense. But sounds like Parametrons might have found a new use.

Recall the optical thingie of post #6. Keep in mind that an optical parametron excited by a single photon with no other logic input would generate a random binary phase shift.
Output at half frequency probably has to emit two photons for powers in and out to be equal. Returning strings of random key'd pulses may look like noise except when tested
for time and phase correlation to a copy kept locally in a delay line. It bugs me that radar would already have to guess the distance better than 1/4 wave before you could even
test wether there was a correlation. Or maybe thats why they are saying its 4 times better than regular radar? Not enough info here to be sure. I'm betting that light is not used,
but some really long microwave instead.
 
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