Voltage-Mode Driver Output Swing Control for Low-Power De-Emphasis
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Voltage-mode drivers for serial/serial (SERDES) applications face challenges in power consumption and controllability of output swing, particularly in advanced technologies where core supply voltage is lower, leading to headroom unreliability and increased power consumption in de-emphasis modes.
Innovation Solution
A circuit design that includes PMOS and NMOS transistors with resistors to create pull-up and pull-down circuits, allowing for controllable output swing in both normal and de-emphasis modes by adjusting transistor resistances and using a de-emphasis circuit to manage impedance matching and voltage levels, reducing crowbar current consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If voltage-mode driver is used for full swing transmission, then power consumption is reduced (5 mA), but output swing becomes uncontrollable and follows supply voltage
Solution Approach 1:
The patent implements dynamic output swing control by introducing a control voltage signal that dynamically adjusts the output swing amplitude. The voltage-mode driver transitions from fixed swing operation to variable swing operation, where the output swing can be dynamically adjusted between full swing and de-emphasis levels based on transmission requirements, while maintaining low power consumption throughout.
Solution Approach 2:
The patent changes the operating parameters of the voltage-mode driver by introducing a control voltage that modulates the output swing amplitude. By varying the control voltage parameter, the driver can operate at different swing levels (full swing or de-emphasis) without changing the fundamental voltage-mode operation, thus maintaining low power consumption while achieving controllability.
2Adaptability or versatility
If current-mode driver is used for reduced swing transmission, then output swing is controllable, but power consumption increases (20 mA)
Solution Approach 1:
The patent creates a universal voltage-mode driver that can perform both full swing and de-emphasis transmission modes. By adding the swing control mechanism, the single voltage-mode driver structure becomes multi-functional, replacing the need for separate current-mode drivers for de-emphasis operation, thus achieving controllability without the high power consumption of current-mode operation.
Solution Approach 2:
The patent implements a voltage-mode copy of the current-mode de-emphasis function. Instead of using actual current-mode circuitry for de-emphasis, the invention creates a voltage-mode equivalent that replicates the de-emphasis functionality through voltage control, thereby achieving the desired output swing control while maintaining the low power consumption characteristics of voltage-mode operation.
3Adaptability or versatility
If de-emphasis mode is achieved by turning on parallel path, then reduced swing is obtained, but power consumption increases (from 5 mA to 7.7 mA)
Solution Approach 1:
The patent extracts the swing control function from the power consumption budget by using a separate control voltage input rather than activating additional power-consuming parallel current paths. The de-emphasis capability is achieved by controlling the existing voltage-mode driver's output swing through the control voltage, eliminating the need for extra current paths that would consume additional power.
Data Source
AI summary
A circuit includes a first node, a second node, a pull-up circuit selectively coupled to the first node or the second node, a pull-down circuit selectively coupled to the first node or the second node, and a resistive circuit. The circuit is configured to operate in a full-swing mode or in a de-emphasis mode based on an electrical coupling of the resistive circuit between the first node and the second node.