Abstract: An optical receiver circuit includes a light receiving element to convert an optical signal into a current signal, a submount substrate on which the light receiving element is mounted, a wiring connected to an anode pad of the light receiving element and a wire connected to a preamplifier on the submount substrate, a wiring to which a bias voltage is applied on the submount substrate; a wiring connected to a cathode pad of the light receiving element on the submount substrate; and a resistor connected to the wiring to serve as a path when the bias voltage is applied to the light receiving element via the wiring on the submount substrate. A resistance value of the resistor is determined such that a resonance peak between the preamplifier and ground is suppressed and that oscillation in the preamplifier is suppressed.

Abstract: An optical receiver includes: a pre-amplifier to convert a current signal into a voltage signal; an LIA to amplify and limit an amplitude of the voltage signal; a transmission line connecting the pre-amplifier with the LIA; an AC coupling capacitor inserted in the middle of the transmission line or at an end of the transmission line; a termination circuit connected with the transmission line, for switching to a first resistance or a second resistance higher than the first resistance in response to a switching signal; and an AC load connected with the transmission line. The AC load is open in a low-frequency range of the voltage signal and having a resistance enabling impedance matching with the pre-amplifier and the transmission line in a high-frequency range of the voltage signal, wherein the termination circuit and the AC load are electrically connected in parallel.

Abstract: An optical receiver circuit includes a light receiving element to convert an optical signal into a current signal, a submount substrate on which the light receiving element is mounted, a wiring connected to an anode pad of the light receiving element and a wire connected to a preamplifier on the submount substrate, a wiring to which a bias voltage is applied on the submount substrate; a wiring connected to a cathode pad of the light receiving element on the submount substrate; and a resistor connected to the wiring to serve as a path when the bias voltage is applied to the light receiving element via the wiring on the submount substrate. A resistance value of the resistor is determined such that a resonance peak between the preamplifier and ground is suppressed and that oscillation in the preamplifier is suppressed.

Abstract: An optical receiver includes: a pre-amplifier to convert a current signal into a voltage signal; an LIA to amplify and limit an amplitude of the voltage signal; a transmission line connecting the pre-amplifier with the LIA; an AC coupling capacitor inserted in the middle of the transmission line or at an end of the transmission line; a termination circuit connected with the transmission line, for switching to a first resistance or a second resistance higher than the first resistance in response to a switching signal; and an AC load connected with the transmission line. The AC load is open in a low-frequency range of the voltage signal and having a resistance enabling impedance matching with the pre-amplifier and the transmission line in a high-frequency range of the voltage signal, wherein the termination circuit and the AC load are electrically connected in parallel.

Abstract: A burst light receiver includes a booster circuit that generates a voltage applied to an avalanche photodiode, a first path in which a resistor to step down the voltage generated by the booster circuit is inserted, a second path provided in parallel to the first path, a switch circuit that is provided between the booster circuit and the first and second paths to select the first path or the second path, a current detecting circuit that controls the switch circuit in such a manner that the booster circuit is connected to the first path when a value of a current flowing from the booster circuit to the avalanche photodiode becomes equal to or larger than a first threshold, and the booster circuit is connected to the second path when the value of the current becomes smaller than a second threshold.

Abstract: An optical receiver includes: a light reception element to convert an input optical signal into a first current signal and output the first current signal; an inverter-based TIA to convert the first current signal into a voltage signal and output the voltage signal using first and second field effect transistors; a current monitor unit to monitor a current magnitude of the first current signal and output a second current signal having a current magnitude based on the current magnitude of the first current signal; and a back-gate adjustment unit to determine a state of an input-output characteristic of the inverter-based TIA on the basis of the second current signal and the voltage signal, and control, on the basis of the determination result, a back-gate terminal voltage of at least one of the first and second field effect transistors.

Abstract: An optical receiver includes an APD that converts an input optical signal into a current signal, a TIA that converts the current signal output from the APD into a voltage signal, an LIA that shapes a waveform of the voltage signal output from the TIA, an AOC having a time constant switching function, the AOC automatically compensating for an offset voltage between differential outputs from the TIA, and a convergence-state detection circuit that outputs, after detecting convergence completion of the automatic compensation in the AOC, to the AOC, a time constant switching control signal for switching a time constant from a high-speed time constant to a low-speed time constant.

Abstract: An optical receiver includes an APD that converts an input optical signal into a current signal, a TIA that converts the current signal output from the APD into a voltage signal, an LIA that shapes a waveform of the voltage signal output from the TIA, an AOC having a time constant switching function, the AOC automatically compensating for an offset voltage between differential outputs from the TIA, and a convergence-state detection circuit that outputs, after detecting convergence completion of the automatic compensation in the AOC, to the AOC, a time constant switching control signal for switching a time constant from a high-speed time constant to a low-speed time constant.

Abstract: A current bypass circuit that passes part of a photocurrent output from a photodetector is connected to an input terminal of a current-to-voltage conversion amplifier circuit. A voltage obtained by level conversion of an output voltage by a voltage level conversion circuit is input into the current bypass circuit so that the current bypass circuit is turned on at a photocurrent that is smaller than the photocurrent at which a diode connected in parallel to a feedback resistor of the current-to-voltage conversion amplifier circuit is turned on. Consequently, the current-to-voltage conversion gain is switched in three stages according to the intensity of the photocurrent corresponding to an optical signal level.

Abstract: A current bypass circuit that passes part of a photocurrent output from a photodetector is connected to an input terminal of a current-to-voltage conversion amplifier circuit. A voltage obtained by level conversion of an output voltage by a voltage level conversion circuit is input into the current bypass circuit so that the current bypass circuit is turned on at a photocurrent that is smaller than the photocurrent at which a diode connected in parallel to a feedback resistor of the current-to-voltage conversion amplifier circuit is turned on. Consequently, the current-to-voltage conversion gain is switched in three stages according to the intensity of the photocurrent corresponding to an optical signal level.