Redriver Resistive Termination for Supply Ramp Voltage Control
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Solution Overview
Problem
Redrivers experience abrupt voltage changes during supply voltage ramp-up or ramp-down, which can damage connected IC chips due to large capacitance values in decoupling capacitors, exceeding the maximum operating voltage of these chips.
Innovation Solution
Incorporating resistive termination units with switches and control circuits that manage the supply voltage changes, using resistors, PMOS transistors, and control signals to regulate voltage at input/output terminals, thereby reducing abrupt voltage changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If decoupling capacitors with large capacitance values are used to isolate DC levels, then signal isolation is improved, but abrupt voltage changes occur during supply voltage transitions that can damage connected IC chips
Solution Approach 1:
A resistive termination unit is introduced as an intermediary component between the redriver and the connected IC chip. This unit includes a resistor and a switch that controls the DC level at the output terminal. The switch is controlled by a control circuit that detects supply voltage transitions and adjusts the termination resistance accordingly, thereby mediating the voltage changes to prevent damage to the IC chip while maintaining signal isolation functionality.
Solution Approach 2:
The control circuit performs preliminary action by detecting supply voltage transitions (ramp-up or ramp-down events) before they cause harmful voltage changes at the output terminal. Upon detecting such transitions, the control circuit activates the switch in the resistive termination unit to adjust the DC level in advance, preventing the abrupt voltage change from reaching the connected IC chip.
2Object-affected harmful factors
If resistive termination units with switches are added to control voltage changes, then voltage control is improved, but device complexity increases
Solution Approach 1:
The resistive termination unit is designed to perform multiple functions: it provides DC level isolation, controls voltage changes during supply transitions, and maintains signal integrity. The same switch and control circuit mechanism handles both ramp-up and ramp-down events, as well as normal operation mode control, thereby reducing the need for separate dedicated circuits for each function and minimizing overall device complexity.
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
The solution effectively controls voltage changes during supply voltage transitions, reducing the risk of damage to IC chips and optimizing current consumption, allowing the redriver to operate in power-saving modes while maintaining signal integrity.
Implementation Method 1
a PMOS transistor connected to the resistor and a supply DC voltage of the redriver
Implementation Method 2
a transmission gate connected to a gate terminal of the PMOS transistor and configured to be turned on or off in response to a change in the supply voltage
Data Source
AI summary
Embodiments of redrivers and resistive termination units for redrivers are disclosed. In an embodiment, a resistive termination unit for a redriver includes a resistor connected to an input/output terminal of the redriver, a first switch connected to the resistor and to a supply voltage of the redriver, a second switch connected to the first switch and configured to be turned on or off in response to a change in the supply voltage of the redriver, and a control circuit connected to the first switch through the second switch and configured to generate a control signal for the first switch.