Transimpedance amplifier (TIA) having an enlarged dynamic range and optical devices using the same

摘要

A gain-variable trans-impedance amplifier (TIA) in optical device is disclosed. The TIA has an improved dynamic range for receiving electrical signals and is configured to convert current signals from an avalanche photodiode (APD) to voltage signals. A resistor element is between the input and output terminals of the TIA, wherein the resistance of the resistor element can regulate the resistance and/or impedance value of the TIA, and a switch determines or controls the resistance of the resistor element. When the power of an optical signal received by the APD is higher than a predetermined value, the resistance becomes smaller and the gain of the TIA becomes greater. When the power of the optical signal is lower than the predetermined value, the resistance becomes greater. The gain of the TIA is automatically adjusted on the basis of the intensity of received optical signals to obtain a greater dynamic operational range.

主权项

1. A trans-impedance amplifier (TIA) with a dynamic range, comprising:
a current amplifier configured to produce an amplified voltage signal from a received current corresponding to a power of a received optical signal, wherein the current amplifier has a reference voltage input terminal, an input terminal and an output terminal; and an impedor between the input terminal and the output terminal of the current amplifier, wherein the impedor has a resistance configured to regulate a resistance and/or impedance value of the TIA; one or more switches configured to determine the resistance of the impedor, wherein the one or more switches are enabled or disabled by a control voltage; and a hysteresis circuit configured to regulate the control voltage by comparing an input voltage corresponding to the received current with a high predetermined value and a low predetermined value, the hysteresis circuit comprising (1) an amplifier having a first input terminal, a second input terminal and an output terminal and (2) a first resistor connected between the first input terminal and the output terminal of said amplifier; wherein when the input voltage is higher than the high predetermined value, the impedor has a first resistance, when the input voltage is lower than the low predetermined value, the impedor has a second resistance greater than the first resistance.