Latching Analog Voltage
Sample & hold, aka track & hold amplifier. You can do a
"poor man's" S/H with op amp and CMOS switches, or you
can find them with the op amps in most analog IC mfrs'
lineup.
However, S/H amps have a finite droop rate (worse w/
temperature and so on). If you are creating these voltages
with a micro & DAC, then probably what you want is to have
a set of registers each with their own DAC. A good S/H amp
may be more expensive than octal latches and DACs.
If this is on the input side then you either want N S/H and
a N:1 mux, to drive a single ADC input channel, or put the
S/H after the mux if you have enough sample interval
(settling time) in your cycle.
The slower you want to run, the more error you will pick up
in the S/H area from the droop rate. In app notes you
should find some guidelines for low-leakage PCB layout,
signal guards and so on (the PCB may be worse for leakage
than the IC elements themselves).