Optical receiver with wide dynamic range transimpedance amplifier

摘要

An optical component is provided that includes a detector configured to transmit an input current to a transimpedance amplifier that includes an automatic transimpedance gain control and DC cancellation control feedback circuit having variable impedance circuitry. Open loop gain of the feedback circuit is independent of the average input current as the input current increases. The feedback circuit includes first and second pnp transistors arranged so that their respective bases are connected and so that an emitter terminal of the first pnp transistor is connected to the input of the transimpedance amplifier, and the impedance seen at the emitter terminal changes according to the average value of the input current. The emitter size of the second pnp transistor is a factor N smaller than emitter size of the first pnp transistor. N can be selected to adjust the gain control and low corner frequency variation with input power.