Resistance-capacitance (RC) coupling
It is also known as capacitive coupling amplifier using this coupling are known as RC coupled amplifier the function RC coupling network is two-fold:
- To pass a signal from one to next
- To block the passage of dc voltage from one stage to next
Impedance coupling or inductive coupling
- It is also known as choke-capacitance coupling amplifiers using this coupling amplifier using this amplifier
are known as impedance coupled amplifier, the impedance of the coupling coil depends on, Its inductance and Signal frequency.
- Moreover, the secondary winding also provides a base return path; hence there is no need for a base resistance. Amplifiers using this coupling are called transformer-coupled amplifier.
- Direct coupling: this coupling is used where it is desirable to connect the load directly in series with the output terminal of the active circuit element.
Direct coupling is permissible only when:
- Dc component of the output does not disturb the normal operation of the load device.
- Device resistance is very low.