What use would a D flip-flop being fed an analog signal have?

Question

I'm contemplating a non-electronic system that is analogous to a D flip-flop being fed an analog signal and a fixed-frequency clock. The system has an analog input which changes over time. The output of the system is a single bit. The analog input is sampled at fixed intervals. The output goes high if the input exceeds one value, and goes low if the input deceeds a lower value.

I feel like this circuit has a name or common application, but I can't track down what it might be.

Answer 1

If the output bit stream is low-pass-filtered and fed back and subtracted from the analog input, you have a first-order delta-sigma tracking converter.

Answer 2

The output goes high if the input exceeds one value, and goes low if the input deceeds a lower value.

That sentence describes a Schmitt trigger: -

Top signal is the input. Middle single is a normal comparator output. Bottom signal is the Schmitt trigger output - notice how it switches high when the analogue input passes the high trigger threshold and only returns to a low output when the analogue input falls below the low trigger input value.

The analog input is sampled at fixed intervals.

That implies a sample and hold circuit: -

It sounds like you are describing a schmitt trigger being fed from the output of a sample and hold circuit that, in turn, is fed from the analogue input.

The output of the system is a single bit.

Yes it is, agreed.

Answer 3

It's an A/D converter, of course. Whatever the D threshold is, at clock time the Q and /Q outputs very quickly settle on a digital representation of the one-bit digitization of the input value (0 for under-threshold, 1 for over-threshold).

A high-resolution digitization, it isn't. But, the captured value is sampled at a very precise time.