ELEC 240 Lab
Introduction
In Lab 3 we saw that the voltage divider was an attenuator:
\(v_\text{out} = \frac{R_2}{R_1 + R_2} v_\text{in} = G v_\text{in}\),
where \(G \le 1\).
If we had a box where \(v_{out} = G v_{in}\) with \(G>1\) we would have an
amplifier.
To be more precise, we would have a
non-inverting,
voltage
amplifier.
If \(G<-1\), we would still be increasing the magnitude of the signal,
but would change its sign.
This is called an
inverting
amplifier.
We could also have a
current amplifier
where
\(i_\text{out} = G_i i_\text{in}\).
Circuits containing only resistors, capacitors, and inductors
(e.g. attenuators or RC filters) are
passive.
An amplifier is an
active
circuit element:
it delivers more power to its load than
it receives from its source.
(In fact this additional power comes from an external power supply,
so no laws of physics are being violated, but when we're drawing
circuit diagrams we usually draw only the amplifier and ignore
the power supply.)