Calculate amplifier input voltage, output voltage, or gain by entering any two values and converting between V, mV, and kV units.
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Amplifier Voltage Formula
The amplifier voltage calculation is based on the relationship between input voltage, amplifier gain, and output voltage.
V_out = V_in * A_v
A_v = V_out / V_in
V_in = V_out / A_v
- V_out = amplifier output voltage
- V_in = input or source voltage
- A_v = voltage gain of the amplifier, unitless
The calculator uses the first formula when you enter input voltage and gain to find output voltage. It uses the second formula when you enter input and output voltage to find gain. It uses the third formula when you enter output voltage and gain to find the required input voltage.
Voltage values are converted to volts for the calculation, then converted back to the unit you selected. Supported voltage units are millivolts, volts, and kilovolts.
Voltage Unit Conversions
| Unit | Symbol | Value in volts |
|---|---|---|
| Millivolt | mV | 0.001 V |
| Volt | V | 1 V |
| Kilovolt | kV | 1,000 V |
Common Gain Values and Output Examples
| Input voltage | Gain | Output voltage | Meaning |
|---|---|---|---|
| 100 mV | 2 | 200 mV | Voltage is doubled |
| 100 mV | 10 | 1 V | Small signal is amplified to volts |
| 1 V | 5 | 5 V | Output is five times the input |
| 2 V | 0.5 | 1 V | Gain below 1 reduces voltage |
Example Problems
Example 1: Calculate output voltage
You have an input voltage of 250 mV and an amplifier gain of 8.
V_out = V_in * A_v
Convert the input voltage to volts:
250 mV = 0.25 V
Apply the gain:
V_out = 0.25 * 8 = 2 V
The output voltage is 2 V.
Example 2: Calculate amplifier gain
You have an input voltage of 0.5 V and an output voltage of 12 V.
A_v = V_out / V_in
A_v = 12 / 0.5 = 24
The amplifier gain is 24.
FAQ
Is amplifier gain measured in volts?
No. Voltage gain is unitless because it is a ratio of output voltage to input voltage. For example, if an amplifier outputs 10 V from a 2 V input, the gain is 5.
Can amplifier gain be less than 1?
Yes. A gain less than 1 means the output voltage is lower than the input voltage. For example, a gain of 0.5 changes a 4 V input into a 2 V output.
Why does the calculator require exactly two values?
The voltage gain equation has three variables: input voltage, gain, and output voltage. If you provide any two of them, the third can be calculated. If fewer or more than two values are entered, there is no single missing value to solve for.
