Section 3. Circuit Examples
3.1 Voltage Divider
The voltage divider circuit is used to downsize a voltage
signal.
It is easy to analyze this circuit if we assume that the current out is zero
(i.e. that the voltage divider is connected to a device
with high impedance.) In this case we apply Ohm's law,
vout = iin R2 and,
vin = iin ( R1 + R2 )
and so
vout / vin = R2 /
( R1 + R2 ) Note that, since negative resistances are impossible, the factor
R2 / ( R1 + R2 ) is always
less than one. A voltage divider therefore attenuates (reduces the
magnitude of) a voltage or voltage signal.