Voltage-Mode Driver De-Emphasis With Bi-Directional Current Reuse
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Solution Overview
Problem
Conventional voltage mode driver de-emphasis circuits consume excessive power due to increased current requirements for de-emphasizing repeated bits in high-speed differential communication links.
Innovation Solution
A bi-directional current source circuit is used in the voltage mode differential circuit, where the current sourced from the positive side is also used to sink into the negative side, reducing overall current consumption and power usage by selectively controlling current flow based on voltage polarity changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If separate uni-directional current sources are used to source and sink current for de-emphasis, then de-emphasis function is achieved, but power consumption increases
Solution Approach 1:
The patent merges the current sourcing and sinking functions into a single bi-directional current source circuit. This circuit can selectively source current from one terminal or sink current to the same terminal depending on the voltage polarity, eliminating the need for separate current sources and reducing overall power consumption while maintaining the de-emphasis function.
Solution Approach 2:
The bi-directional current source circuit performs multiple functions: it can source current in one direction, source current in the opposite direction, and sink current, all within a single circuit implementation. This multi-functionality allows the circuit to adapt to different voltage polarity conditions and achieve de-emphasis with reduced power consumption.
2Reliability
If more current is provided to de-emphasize repeated bits, then de-emphasis effectiveness increases, but power consumption increases
Solution Approach 1:
The bi-directional current source circuit operates periodically based on the voltage polarity changes in the differential signal. It activates current sourcing or sinking only when needed during polarity transitions, rather than continuously providing current, thereby achieving effective de-emphasis while minimizing power consumption.
Solution Approach 2:
The circuit dynamically changes its operating parameters by switching between sourcing and sinking modes based on voltage polarity. This parameter change allows the circuit to provide the necessary current for de-emphasis only when required, reducing overall power consumption while maintaining effectiveness.
Data Source
AI summary
A circuit for de-emphasizing information transmitted via a differential communication link (226) includes a voltage mode differential circuit (225) and a bi-directional current source circuit (308). The voltage mode differential circuit (225) includes a first and second output terminal (316, 318). The voltage mode differential circuit (225) provides a first voltage via the first output terminal (316) and second voltage via the second output terminal (318) in response to a differential input voltage. The bi-directional current source circuit (308) is operatively coupled between the first and second terminals. The bi-directional current source circuit (308) selectively provides current in a first and second direction between the first and second terminals based on the first and second voltage.