Optical Receiver Peaking Circuit for Stable Frequency Response

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Solution Overview

Problem

Conventional optical receiving devices face a trade-off between light-receiving sensitivity and gain, leading to deteriorated frequency response and reception sensitivity characteristics due to excessive peaking from mounting conditions, circuit design, and manufacturing variations.

Innovation Solution

Incorporating a resistor and capacitor connected in series between the signal line and GND, along with an optional inductor, to achieve impedance matching and suppress peaking, thereby improving the reception sensitivity characteristic.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Area of stationary object

If peaking is applied to extend the passband, then the passband is extended, but the frequency response characteristic deteriorates due to manufacturing variations

Engineering Contradiction:

ImprovepassbandVSAvoidfrequency response characteristic

Core Design Contradiction:

Area of stationary objectVSReliability

Solution Approach 1:

A damping resistor is introduced as an intermediary element between the peaking inductor and the output terminal. This resistor acts as a mediator that suppresses the excessive peaking effect caused by manufacturing variations in the inductor, thereby stabilizing the frequency response characteristic while preserving the extended passband benefit

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The damping resistor changes the electrical parameters of the circuit by introducing resistance that counteracts the excessive inductive reactance. This parameter modification suppresses the peaking phenomenon and stabilizes the frequency response across different manufacturing variations

Inventive Principle:

Principle #35Parameter changes

2Area of stationary object

If peaking is applied excessively, then the passband is extended, but the reception sensitivity characteristic deteriorates

Engineering Contradiction:

ImprovepassbandVSAvoidreception sensitivity characteristic

Core Design Contradiction:

Area of stationary objectVSMeasurement precision

Solution Approach 1:

The damping resistor serves as an intermediary that reduces the excessive peaking effect, thereby improving the reception sensitivity characteristic while maintaining the extended passband advantage

Inventive Principle:

Principle #24Intermediary (Mediator)

3Device complexity

If manufacturing variations occur in the pre-amplifier or inductor, then device complexity is reduced, but the frequency response characteristic deteriorates

Engineering Contradiction:

Improvecircuit designVSAvoidfrequency response characteristic

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The damping resistor is introduced as a simple intermediary element that compensates for manufacturing variations without adding complex circuitry, thereby maintaining low device complexity while improving frequency response characteristic reliability

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The damping resistor provides beforehand cushioning against the adverse effects of manufacturing variations. By pre-introducing this damping element, the circuit is prepared to withstand the variability in inductor and pre-amplifier characteristics, ensuring stable frequency response

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

Data Source

PatentUS8859946B2Light detecting device including a peaking circuit

Publication Date: 2014.10.14 MITSUBISHI ELECTRIC CORP

AI summary

An optical detecting device includes a light-detecting element for outputting an electrical signal, a pre-amplifier for amplifying the electrical signal, a signal line connected to an output of the pre-amplifier, and a resistor and a capacitor connected in series between the signal line and GND.