PAM Output Circuit Current Stabilization for Supply Line Integrity

Solution Overview

Problem

Existing PAM4 output circuits cause fluctuations in power supply line potential, leading to deterioration of the eye pattern and increased circuit area and cost due to the use of large-capacitance bypass capacitors.

Innovation Solution

An output circuit with a differential circuit and a switch-resistor path connecting power supply lines, along with a disconnector, to stabilize current flow and suppress power supply line fluctuations, reducing the need for large capacitors.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a large-capacitance bypass condenser is connected to the power supply line to suppress potential fluctuation, then the power supply line potential stability is improved, but the circuit area and cost increase

Engineering Contradiction:

Improvepower supply line potential stabilityVSAvoidcircuit area

Core Design Contradiction:

ReliabilityVSArea of stationary object

Solution Approach 1:

A current suppression circuit is introduced as an intermediary component between the differential circuit and the power supply line. This circuit includes a switch element connected in parallel with the differential output circuit and a resistor element connected in series with the switch element, forming a current suppression path. The intermediary circuit suppresses current changes flowing from the power supply line by providing an alternative current path, thereby stabilizing the power supply line potential without requiring large-capacitance bypass condensers.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If a large-capacitance bypass condenser is connected to the power supply line to suppress potential fluctuation, then the power supply line potential stability is improved, but the cost increases

Engineering Contradiction:

Improvepower supply line potential stabilityVSAvoidmanufacturing cost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

A current suppression circuit is introduced as an intermediary component between the differential circuit and the power supply line. This circuit includes a switch element connected in parallel with the differential output circuit and a resistor element connected in series with the switch element, forming a current suppression path. The intermediary circuit suppresses current changes flowing from the power supply line by providing an alternative current path, thereby stabilizing the power supply line potential without requiring large-capacitance bypass condensers.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Adaptability or versatility

If the differential circuit operates with multiple voltage values to transmit information, then the information transmission capability is improved, but the current fluctuation on the power supply line increases

Engineering Contradiction:

Improveinformation transmission capabilityVSAvoidcurrent fluctuation

Core Design Contradiction:

Adaptability or versatilityVSObject-generated harmful factors

Solution Approach 1:

A current suppression circuit is introduced as an intermediary component between the differential circuit and the power supply line. This circuit includes a switch element connected in parallel with the differential output circuit and a resistor element connected in series with the switch element, forming a current suppression path. The intermediary circuit suppresses current changes flowing from the power supply line by providing an alternative current path, thereby stabilizing the power supply line potential without requiring large-capacitance bypass condensers.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The invention converts the harmful current fluctuation generated by the differential circuit into a beneficial effect. By providing a current suppression path with a switch element and resistor element, the circuit transforms the current variation into a controlled current flow through the suppression path, which stabilizes the overall power supply line current and reduces potential fluctuation.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Data Source

PatentUS12546651B2Output circuit that outputs amplitude modulated signal having voltage value selected from three or more voltage values

Publication Date: 2026.02.10 CANON KK

AI summary

Output circuit includes differential circuit arranged between first and second power supply lines, and switch and resistor connected in series between the first and second power supply lines. The differential circuit includes first differential output circuit including first positive-side output terminal and first negative-side output terminal, second differential output circuit including second positive-side output terminal and second negative-side output terminal, first output line connecting the first positive-side output terminal and the second positive-side output terminal, and second output line connecting the first negative-side output terminal and the second negative-side output terminal, amplitude modulated signal is output by the first and second output lines. The switch and the resistor suppress change in current flowing between the first and second power supply lines. The output circuit further includes disconnector to disconnect the second differential output circuit from the first differential output circuit.