Differential Current Line Driving With Common-Mode Equalization
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Solution Overview
Problem
Differential current driving type data transmission systems face signal distortion and increased error rates due to parasitic inductance and noise interference, which complicates signal recovery and increases power consumption.
Innovation Solution
The system introduces a common mode drive interval with a higher turn-on resistance in the equalizing switch and uses diode-connected MOS transistors for I-V conversion, minimizing current differences and eliminating the need for current mirrors to reduce errors and power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If more current is supplied to the transmission line to overcome signal distortion and interference, then the voltage difference at the receiving end becomes greater and error rate decreases, but power consumption increases and Electromagnetic Interference (EMI) between transmission lines increases
Solution Approach 1:
The patent changes the driving mode from single-ended to differential current driving, and introduces common mode voltage control to adjust the operating parameters of the transmission line. By controlling the common mode voltage, the system optimizes the voltage difference at the receiving end without increasing current, thereby reducing power consumption while maintaining low error rates
Solution Approach 2:
The patent introduces a common mode voltage as an intermediary control parameter. This common mode voltage acts as a mediator that adjusts the operating point of the differential pair, enabling the system to achieve better signal recovery without increasing the differential current, thus resolving the contradiction between reliability and power consumption
2Reliability
If more current is supplied to the transmission line to overcome signal distortion, then signal distortion is minimized, but Electromagnetic Interference (EMI) between transmission lines increases
Solution Approach 1:
The patent replaces current-based signal driving with voltage-based common mode control. Instead of increasing current to reduce distortion, the system uses common mode voltage control to manage signal integrity, thereby reducing EMI while maintaining low distortion levels
Solution Approach 2:
The patent changes the control parameter from current magnitude to common mode voltage level. By adjusting the common mode voltage, the system achieves better signal distortion control without increasing the differential current, thus minimizing EMI between transmission lines
3Reliability
If complex circuits such as amplifiers are added at the receiving end to recover original signals from distorted signals, then signal recovery capability is improved, but circuit complexity increases and error rate during signal recovery gets higher
Solution Approach 1:
The patent applies preliminary action by pre-equalizing the transmission line characteristics through common mode voltage control before the signal reaches the receiving end. This preliminary adjustment reduces signal distortion in advance, eliminating the need for complex equalization circuits at the receiver and simplifying the overall system while maintaining high signal recovery capability
4Area of stationary object
If signal lines are placed closer together to reduce interference distance, then the system becomes more compact, but interference between transmission lines increases in proportion to the distance reduction
Solution Approach 1:
The patent converts the harmful close-coupling interference into a beneficial common mode signal. By using differential current driving with common mode voltage control, the interference that would normally be harmful is transformed into a controllable common mode component that can be managed through voltage adjustment, allowing compact layout while maintaining signal integrity
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach minimizes signal distortions, reduces error rates, and lowers overall current consumption during signal recovery without increasing the transmission current, effectively addressing the challenges of parasitic inductance and noise interference.
Implementation Method 1
uses diode-connected MOS transistors for I-V conversion, minimizing current differences and eliminating the need for current mirrors
Implementation Method 2
introduces a common mode drive interval with a higher turn-on resistance in the equalizing switch
Implementation Method 3
a differential current driving type data transmission system, supplies different currents to two signal lines in open drain ways, so that a receiving end can recover an original signal based on a voltage difference
Data Source
AI summary
A differential current driving type data transmission system includes a line drive controller for outputting differential transmission signals and common mode line control signals, in response to a transmission signal; current sources for generating an excitation current and a base current and for driving positive/negative transmission lines with the base current; a first switch for selectively switching the excitation current to the positive/negative transmission lines, in response to the differential transmission signals; and a second switch for equalizing the positive/negative transmission lines within a common mode interval, in response to the common mode line control signals, wherein, in the common mode, the positive/negative transmission lines are driven at a level above or below an intermediate current level by a predetermined common mode current difference.