Dptical receiving machine

Abstract

A photoreceptor is provided with an erroneous operation detection circuit for monitoring an output signal supplied from a slew rate variable output stage. The erroneous operation detection circuit performs such controls that a slew rate of output is decreased within a range in which a transmission speed of the slew rate variable output stage is not decreased. With this arrangement, it is possible to inhibit adverse effect on the output signal due to a parasite current caused between an output terminal of the photoreceptor and photoelectric converting means, such as a photodiode.

Description

technical field [0001] The present invention relates to an optical receiver for converting an optical signal into a digital electric signal and outputting it for applications such as optical fiber-linked digital audio. In particular, it relates to an optical receiver having an optoelectronic integrated circuit called an OEIC (Optoelectronic IC) integrating a light receiving element and a signal processing circuit on one chip. Background technique [0002] Fig. 11 is a block diagram showing a schematic configuration of a typical prior art optical receiver for optical fiber used in digital audio. In this optical receiver, a photodiode PD11 that receives an optical signal transmitted through an optical fiber and a signal processing circuit that performs signal processing based on an output from the photodiode PD11 are provided. The photodiode PD11 generates a current signal proportional to the intensity of the light signal. The photocurrent detected by the photodiode PD11 is ...

AI Technical Summary

Problems solved by technology

Therefore, the (dV / dt) of the parasitic current I=C×(dV / dt) becomes large, and it is easy to operate incorrectly

Moreover, even if it is adjusted so that there is no misoperation when the power supply voltage is 3V, when the power supply voltage is 5V, tr and tf become shorter, the output amplitude increases, and the parasitic current becomes larger, resulting in misoperation

In addition, if tr and tf are adjusted so that malfunction does not occur when the power supply voltage is 5V, if the power supply voltage becomes 3V, tr and tf will be delayed, the speed of the signal that can be transmitted is limited, and it is difficult to realize the operating power supply voltage range wide high-speed digital output receiver

[0041] In addition, according to Japanese Patent Publication No. 3018541 (issue date: March 13, 2000), an output circuit that switches the slew rate of the output in two stages based on an external slew rate control signal is disclosed. Among them, since the slew rate of the output can only be controlled in 2 stages, it is very difficult to control the slew rate very finely within the range that can suppress malfunction

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