In electronics, a transimpedance amplifier is an amplifier that converts current to voltage. Its input ideally has zero impedance, and the input signal is a current. Its output may have low impedance, or in high-frequency applications, may be matched to a driven transmission line; the output signal is measured as a voltage.
Because the output is a voltage and the input is a current, the gain, or ratio of output to input, is expressed in units of ohms.
When constructed as a simple operational amplifier circuit (right), the gain is equal to the negative of feedback resistance.
Transimpedance amplifiers are commonly used in receivers for optical communications to convert the current generated by a photodetector into a voltage signal for further amplification.
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