Question

1. Active filter usually have what type of components that give them the designation ‘active’?
2. A digital signal’s ringing is usually found in what part of the pulse? Draw its diagram and indicate these locations.
3. If one had the choice between a standard relaxation R/C oscillator and a crystal oscillator, what would be the decision criteria in selecting one or the other?

Answer 1

Answer :

Active Filters usually consists of active components such as Operational amplifiers, Transistors or FET's ( Field Effect Transistor ) which gives them the designation 'Active' .

The choice of oscillator is dependent on the frequency and the kind of applications , If we need to produce lower frequencies, mostly audio frequencies, in such applications such as audio signal generators and electronic musical instruments standard relaxation R/C oscillator is preferable .

But if the demand of frequency is stable then Crystal oscillators are preferable .These  are used in applications where a very stable frequency is required. In RC oscillators the oscillator frequency changes due to change in temperature, power supply voltage or even slight change in the component values.

Thus If one had the choice between a standard relaxation R/C oscillator and a crystal oscillator . The decision criteria for the selection would be the Frequency .