Electronics Handbook/Circuits/Voltage Divider

Voltage Divider
If two circuit elements are in series, there is a voltage drop across each element, but the current through both must be the same. The voltage at any point in the chain divides according to the resistances. A simple circuit with two (or more) resistors in series with a source is called a voltage divider.


 * [[Image:PotentialDivider.png|120px]]

Figure A: Voltage Divider circuit.

Transfer Function of Voltage Divider
Consider the circuit in Figure A. According to KVL the voltage $$V_{in}$$ is dropped across resistors $$R_1$$ and $$R_2$$. If a current i flows through the two series resistors then by Ohm's Law.


 * $$i = \frac{V_{in}}{R_1+R_2}$$.

So
 * $$ V_{out}=iR_2 \,\!$$

Therefore
 * $$ V_{out}=V_{in} \frac{R_2}{R_1+R_2}$$
 * $$ V_{out} = V_{in} \frac{R_2}{R_1 + R_2}$$