Mitsubishi Electric Corporation

Daisuke Mita

Masaki Noda

Masamichi Nogami

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.

Optical receiver circuit, optical receiver, optical terminal device, and optical communication system

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.

Optical receiver, optical terminal, and optical communication system

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.

Optical receiver, optical termination device, and optical communication system

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.

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Tokyo, Japan

Daisuke Mita