What is input impedance and output impedance?
The output impedance refers to the impedance, or opposition to current flow, of the component that often bears an electrical source to “drive” a load component. Meanwhile, the input impedance refers to the load component’s opposition to current flowing in from the electrical source.
What is the input impedance of a common emitter amplifier?
around 1kΩ
Common emitter amplifier impedance levels One of the key attributes to be considered when undertaking any electronic circuit design are the impedance levels. The input impedance is typically around 1kΩ, although this can vary considerably according to the circuit values and conditions.
How do you find the impedance of an emitter follower?
Output Impedance: if removing Re and Rc, Zout = 2Mohm/(100+1). With Rb and Rc in place, according to AoE formula, Z_source = 2Mohm/(100+1) + 10kohm + 1kohm = 30,801.980198 ohm (the resistance looking into emitter in the perspective of the load, or R_e).
How do you find the input impedance?
The generalised formula for the input impedance of any circuit is ZIN = VIN/IIN. The DC bias circuit sets the DC operating “Q” point of the transistor and as the input capacitor, C1 acts as an open circuit and blocks any DC voltage, at DC (0Hz) the input impedance (ZIN) of the circuit will be extremely high.
What is the use of an emitter follower?
Emitter follower is a negative current feedback circuit. Emitter follower configuration, also known as Common collector, provides high input impedance and low output impedance. So they are used for the purpose of impedance matching.
What is the effect of an emitter follower?
• Emitter follower lowers the source impedance by a factor of β+1 Æimproved driving capability. • Since rO is in parallel with RE, its effect can be easily incorporated into voltage gain and input and output impedance equations. • There is a current gain of (β+1) from base to emitter.
How did the emitter follower amplifier get its name?
This name is derived from the fact that the emitter voltage “follows” that of the base circuit – the circuit has unit voltage gain. The emitter follower transistor amplifier has a very straightforward circuit.
How is the emitter follower of a transistor chosen?
The emitter follower can be designed and electronic component values determined using the design flow below as a basis: Choose transistor: As before, the transistor type should be chosen according to the anticipated performance requirements.
Can a common collector buffer be coupled to an emitter follower?
It is not always possible to directly couple the emitter follower, common collector buffer. When this is the case, it is necessary to add a few additional electronic components: coupling capacitors and bias resistors to the circuit.