Differential Signaling Driver With Direct Common-Mode Voltage Setting
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Differential signaling circuits face common mode noise issues due to floating common mode nodes, leading to inaccurate output signals and instability, and existing solutions with common mode feedback loops result in either instability or low operation speed.
Innovation Solution
A differential signaling driver design that includes a current source, a differential signal generator, and a resistor network, where the differential signal generator couples output nodes to either the operation voltage or ground voltage based on the digital input signal, eliminating the need for a common mode feedback loop and allowing independent adjustment of common mode voltage and differential output voltages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a common mode feedback loop is incorporated into the differential signaling circuit to control the common mode voltage, then the common mode voltage can be controlled, but the differential signaling circuit experiences either instability or low operation speed
Solution Approach 1:
The patent extracts and removes the common mode feedback loop from the differential signaling circuit. By eliminating this feedback mechanism, the circuit avoids the instability and low operation speed problems that arise from feedback loops, while still achieving common mode voltage control through an alternative direct control architecture
Solution Approach 2:
The patent segments the control functions by separating common mode voltage control from differential signal transmission. The common mode voltage is controlled independently through dedicated control terminals without affecting the differential signaling path, allowing both functions to operate optimally without interference
2Measurement precision
If a common mode feedback loop is incorporated into the differential signaling circuit to control the common mode voltage, then the common mode voltage can be controlled, but the operation speed of the differential signaling circuit decreases
Solution Approach 1:
The patent removes the feedback loop mechanism that inherently introduces delay and reduces operation speed. By using direct control terminals for common mode voltage adjustment without feedback circulation, the circuit achieves fast response times while maintaining precise common mode voltage control
Solution Approach 2:
The patent implements preliminary action by providing direct control terminals that allow the common mode voltage to be set to desired values before differential signaling operations begin. This pre-setting capability eliminates the need for continuous feedback adjustment during high-speed operation, maintaining both precision and speed
3Device complexity
If the common mode node between differential output nodes is floating, then the circuit structure is simple, but the common mode voltage becomes a random voltage leading to inaccurate output signals
Solution Approach 1:
The patent introduces control terminals as intermediary elements that mediate between the power supply and the common mode node. These terminals allow precise control of the common mode voltage without requiring complex feedback circuits, maintaining structural simplicity while ensuring accurate output signals through controlled common mode voltage levels
Data Source
AI summary
A differential signaling driver includes a current source, a differential signal generator, and a resistor. The current source is connected between an operation voltage and a first node, and supplies a driving current to the first node. The differential signal generator is connected between the first node and a second node. The differential signal generator receives a digital input signal, and generates a pair of differential output signals at a first output node and a second output node according to the digital input signal. The resistor is connected between the second node and a ground voltage. The differential signal generator couples the first output node to the operation voltage and the second output node to the ground voltage or couples the first output node to the ground voltage and the second output node to the operation voltage according to the digital input signal.