DC-AC Pre-Amplifier Circuit for Low-Power AC-Coupled Receivers

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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 the receiver can operate in AC-coupled mode, but additional power consumption occurs

Engineering Contradiction:
ImproveAC-coupled transmission capabilityVSAvoidpower consumption
Core Design Contradiction:
Adaptability or versatilityVSUse of energy by moving object

Solution Approach 1:

The existing common mode generation circuit is designed to serve dual purposes: it generates the common mode signal for DC-coupled mode operation and simultaneously provides the common mode signal for AC-coupled mode operation. This eliminates the need for a separate switchable circuit, maintaining adaptability while avoiding additional power consumption.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent merges the AC-coupled common mode generation function with the existing DC-coupled common mode generation circuit. By combining these functions into a single circuit architecture, the system achieves AC-coupled transmission capability without adding separate power-consuming components.

Inventive Principle:
Principle #5Merging (Combining)

2Adaptability or versatility

If a level shifter and resistors are added to the common mode generation circuit, then AC-coupled data transmission is enabled, but power consumption overhead increases

Engineering Contradiction:
ImproveAC-coupled data transmissionVSAvoidpower consumption overhead
Core Design Contradiction:
Adaptability or versatilityVSLoss of energy

Solution Approach 1:

The common mode generation circuit is designed to universally support both DC-coupled and AC-coupled transmission modes using the same circuit components. The existing level shifter and resistors are configured to provide appropriate common mode levels for both coupling modes, eliminating the need for additional power-consuming components.

Inventive Principle:
Principle #6Universality (Multi-functionality)

3Reliability

If the common mode level V CM-TX is aligned with V CM-RX in DC-coupled mode, then proper signal reception is achieved, but additional circuitry is required for AC-coupled mode

Engineering Contradiction:
Improvesignal reception accuracyVSAvoidcircuitry complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The common mode generation circuit is designed to universally provide appropriate common mode levels for both DC-coupled and AC-coupled transmission modes. The same circuit components and architecture serve both modes, maintaining signal reception accuracy while avoiding additional circuitry complexity.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Data Source

PatentEP4568108A1Low power DC-ac coupled pre-amplifier circuits for high-speed link receivers
Publication Date: 2025.06.11 STMICROELECTRONICS INT NV
  • EP4568108A1 patent drawingFigure 1
  • EP4568108A1 patent drawingFigure 2
  • EP4568108A1 patent drawingFigure 3

AI summary

A receiver includes a pre-amplifier circuit (102) and an amplifier circuit (104). The pre-amplifier circuit (102) includes first and second input terminals that receive signals from a transmitter; first and second output terminals that output signals to the amplifier circuit (104); a first resistor having a first terminal coupled to the first input terminal, and a second terminal coupled to a first node (N1); a second resistor having a first terminal coupled to the second input terminal, and a second terminal coupled to the first node (N1); a third resistor having a first terminal coupled to the first output terminal, and a second terminal coupled to a second node (N2); a fourth resistor having a first terminal coupled to the second output terminal, and a second terminal coupled to the second node (N2); and a switch (S) having a first terminal coupled to the first node (N1), and a second terminal coupled to the second node (N2).