DC-AC Pre-Amplifier Circuit for Low-Power Common Mode Alignment

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Solution Overview

Problem

Conventional high-speed link receivers require additional power-consuming circuitry for AC-coupled transmission, as they need to align the common mode levels between the transmitter and receiver.

Innovation Solution

A DC-AC pre-amplifier circuit that generates an input common mode signal using an internal common mode signal, eliminating the need for an input common mode generation circuit, thereby reducing power consumption during AC-coupled transmission.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a switchable internal common mode generation circuit is added to enable AC-coupled transmission, then AC-coupled data transmission is achieved, but power consumption increases

Engineering Contradiction:

ImproveAC-coupled transmission capabilityVSAvoidpower consumption

Core Design Contradiction:

Adaptability or versatilityVSUse of energy by moving object

Solution Approach 1:

The patent extracts and eliminates the separate common mode generation circuit from the receiver design. Instead of adding a dedicated circuit to generate common mode signals, the invention utilizes the existing internal common mode signal already present in the receiver, thereby removing the need for additional power-consuming components while maintaining AC-coupled transmission capability

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent makes the existing internal common mode signal serve multiple functions. The same internal common mode signal that is used for normal receiver operation is also utilized to provide the common mode signal required for AC-coupled transmission, eliminating the need for a separate common mode generation circuit and reducing overall power consumption

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Adaptability or versatility

If additional circuitry is added to align common mode levels in AC-coupled mode, then common mode alignment is achieved, but device complexity increases

Engineering Contradiction:

Improvecommon mode level alignmentVSAvoidcircuit complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent merges the common mode signal generation function with the existing receiver signal processing path. By combining the internal common mode signal generation with the AC-coupled transmission path, the invention eliminates the need for separate alignment circuitry such as resistors and level shifters, thereby reducing device complexity while maintaining common mode alignment capability

Inventive Principle:

Principle #5Merging (Combining)

Data Source

PatentUS20250184188A1Low power DC-ac coupled pre-amplifier circuits for high-speed link receivers

Publication Date: 2025.06.05 STMICROELECTRONICS INT NV

AI summary

Disclosed is a receiver that includes a pre-amplifier circuit and an amplifier circuit. The pre-amplifier circuit includes first and second input terminals that receive signals from a transmitter; first and second output terminals that output signals to the amplifier circuit; a first resistor having a first terminal coupled to the first input terminal, and a second terminal coupled to a first node; a second resistor having a first terminal coupled to the second input terminal, and a second terminal coupled to the first node; a third resistor having a first terminal coupled to the first output terminal, and a second terminal coupled to a second node; a fourth resistor having a first terminal coupled to the second output terminal, and a second terminal coupled to the second node; and a switch having a first terminal coupled to the first node, and a second terminal coupled to the second node.