Reconfigurable Tx Driver H-Bridge for Fast Common-Mode Recovery
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Solution Overview
Problem
Conventional Tx drivers in SerDes environments are slow in re-establishing the common mode, which affects device responsiveness, particularly in wake-up events, and require additional hardware to achieve faster re-establishment.
Innovation Solution
Implementing a reconfigurable H-bridge circuit that selectively activates and deactivates pull-up and pull-down segments to increase charging current, switching between quick charge/discharge modes and classical margining to rapidly re-establish the common mode voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If conventional Tx driver designs are used with classical margining mode, then the common mode can be re-established, but the re-establishment speed is slow and device responsiveness is reduced
Solution Approach 1:
The H-bridge circuit is made reconfigurable, allowing it to dynamically switch between different operating modes (classical margining, quick charge, quick discharge) based on the voltage state of the AC-capacitor. This dynamic adaptation enables the circuit to optimize its performance for rapid common mode re-establishment while maintaining stability when needed.
Solution Approach 2:
The patent changes the operating parameters of the H-bridge circuit by introducing quick charge and quick discharge modes that use higher current levels than classical margining. By controlling the pull-up and pull-down segments to operate at elevated current levels during transient states, the circuit achieves faster voltage transitions and common mode re-establishment.
2Loss of time
If higher charging current is used to speed up common mode re-establishment, then re-establishment time is reduced, but additional hardware complexity is required
Solution Approach 1:
The H-bridge circuit is designed to perform multiple functions: classical margining for stable operation, quick charge for rapid voltage increase, and quick discharge for rapid voltage decrease. By making the existing H-bridge reconfigurable, the patent achieves multiple functions without adding separate dedicated circuits, thereby reducing overall hardware complexity.
Solution Approach 2:
The H-bridge is divided into controllable pull-up and pull-down segments that can be independently activated. This segmentation allows the circuit to selectively engage only the necessary segments for the current operation mode, enabling rapid charge/discharge when needed while maintaining simplicity during normal operation.
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 significantly reduces the time required to re-establish the common mode voltage, enhancing device responsiveness while minimizing additional hardware requirements.
Implementation Method 1
an AC-capacitor coupling the Tx driver to the receiver in the system
Implementation Method 2
P-channel MOSFET (metal-oxide-semiconductor field-effect transistor) (''PMOS'') 106, PMOS 108, resistor 128, resistor 130, N-channel MOSFET (''NMOS'') 112, NMOS 114
Data Source
AI summary
A method, control apparatus, and system for re-establishing a common mode in a transmitter involve switching a driver circuit of the transmitter to a quick charge or quick discharge mode based on an output value of the transmitter. When the output later exceeds a programmable common mode voltage, the driver circuit is switched to a classical margining mode to bring the output back towards the targeted common mode voltage. The modes are switched by adjusting the number of activated pull-up and pull-down segments. More pull-up segments and less pull-down segments are activated in the quick charge mode than the classical margining mode. More pull-down segments and less pull-up segments are activated in the quick discharge mode than the classical margining mode.