Ethernet Transmitter Output Stage for Impedance Correction
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Solution Overview
Problem
Conventional Ethernet transmitter circuits face challenges in correcting termination resistors due to low withstand voltage of transmission gates in advanced manufacturing processes.
Innovation Solution
The output stage of the Ethernet transmitter includes a resistor coupled between first and second output terminals, and a first transistor group with multiple transistors connected in parallel, allowing current adjustment to correct characteristic impedance without relying on serial connection of transmission gates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If transmission gates are used to correct termination resistors, then the termination resistor correction is achieved, but the withstand voltage capability deteriorates in advanced manufacturing processes
Solution Approach 1:
The patent changes the correction mechanism from using transmission gates (which have low withstand voltage) to using current source circuits that can operate at higher voltages. The correction is achieved by adjusting current parameters rather than relying on voltage-based transmission gate switching, thereby resolving the contradiction between achieving precise termination resistor correction and maintaining high withstand voltage capability in advanced manufacturing processes
Solution Approach 2:
The patent replaces the mechanical/electronic switching mechanism (transmission gates) with a current-based control mechanism. Instead of using transmission gates that physically switch connections, the invention uses controlled current sources to achieve the same correction function, substituting a voltage-based system with a current-based system that has superior voltage withstand capabilities
2Manufacturing precision
If transmission gates are used for termination resistor correction, then the correction function is implemented, but the reliability deteriorates due to low withstand voltage
Solution Approach 1:
The patent changes the operational parameters from voltage-based transmission gate control to current-based control, enabling the circuit to operate reliably at higher voltages. This parameter change eliminates the reliability issues associated with transmission gates having low withstand voltage, while maintaining the termination resistor correction function through current adjustment
3Manufacturing precision
If conventional correction method with transmission gates is used, then the termination resistor correction is achieved, but the adaptability to advanced manufacturing processes deteriorates
Solution Approach 1:
The patent changes the correction approach to use current sources instead of transmission gates, making the circuit adaptable to advanced manufacturing processes that operate at higher voltages. This parameter change enables the correction function to work effectively in modern manufacturing contexts where transmission gates would fail due to their low withstand voltage characteristics
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 solution effectively corrects the characteristic impedance by adjusting the current flowing through the output stage, making it suitable for advanced manufacturing processes and improving the reliability of Ethernet transmitter circuits.
Implementation Method 1
a magnitude of a current flowing to the first output terminal is related to the number of transistors that are turned on
Data Source
AI summary
An output stage of an Ethernet transmitter is provided. The output stage is coupled to a resistor and includes a first output terminal, a second output terminal, a first transistor, and a first transistor group. The resistor is coupled between the first output terminal and the second output terminal. The first transistor has a first source, a first drain, and a first gate, the first source being coupled to a first reference voltage and the first drain being coupled to the second output terminal. The first transistor group is coupled to the first reference voltage and the first output terminal. The first transistor group includes multiple transistors which are connected in parallel, and the magnitude of the current flowing to the first output terminal is related to the number of transistors that are turned on.