I have a basic doubt about discrete time circuits.
A discrete - time signal is a sequence of values which are taken at specific time instants (let's call them sampling instants), as we can see from the following picture:
So, from what I have understood, a discrete - time signal is in general like an analog signal which has been sampled, and it is not exactly equal to a digital signal because its values have not been quantized yet (so they may assume values inside a continuous set of numbers).
My question is about the physical implementations of discrete time circuits (for instance discrete - time filters).
For instance, this is a switched capacitor integrator:
If I have understood it correctly, it performs integration during the sampling instants (in which the capacitor C1 acts like a resistor).
But my question is: obviously the circuital elements (op - amp etc) are ON during all time, in general, and at the output we will have a signal for each time. What does it happen during the time between two sampling instants and how discrete - time filters manage it?