Analog RAM and D-FilpFlop?

An 'analog' RAM is sometimes known as a sample and hold, but it doesn't hold for very long. Such circuits are usually used in front of an A-D, so the analog value may be stored as a digital value.

It is possible to make an analog storage cell, but it's far easier to use an A-D (in general, at least).

Cheers

Petes

I tried that before *bucket brigade*. Everything I saw refers to cameras.

Google for 'digital bucket brigade'.

Don

Multilevel Flash memory stores multiple bits per cell by placing variable amounts of charge on a floating mosfet gate. The charge level sits there, essentially unchanged, for many years.

There is an equivalent voice storage technology that stores analog samples in eeprom-type cells.

One of the first digital computers stored bits on discrete capacitors, mounted on a rotating drum, accessed sequentially by brushes.

John

I'd suggest googling 'charge coupled device'. Once popular for audio delays for example.

Graham

Check this out.

You need to get creative to get the best out of google.

Graham

Nice ref.

On a more modern note, Intersil is making some very nice voltage reference chips with no "reference" at all. They're essentially silicon capacitors charged up to the desired voltage and buffered with a cmos opamp. They factory calibrate them (by tunneling or something) and ship! The voltage just hangs there sort of forever.

I was impressed.

John

How about CRT storage methods ?

Graham

That's astonishing !

Graham

all I can think of is magnetic tape or a delay line

for most applications better precision can be had for less cost by converting to digital.

Or ionizing radiation.

Wonder if a strong electric field can upset them?

...Jim Thompson

Sure. Xrays were used to erase the original eproms (three or four times, then the silicon was destroyed.)

A rough calculation suggests the floating gate on the Intersil reference leaks less than an electron per hour.

John

for analog NV-RAM.... ISD Winbond Audio chips.

ISD4004 etc

JG

I wonder if you could use them as dosemeters. I don't have a source of x-rays to test this possibility, but one of you guys might have an x-ray machine for inspecting the soldering of BGAs. You could measure the reference voltage with a good voltmeter before and after exposing the chip.

Chris