Redriver Resistive Termination for Safe Mode Switching
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Solution Overview
Problem
Redrivers switching between operational modes can cause abrupt voltage changes at input/output terminals, potentially damaging IC chips due to large capacitance values of decoupling capacitors, especially when the absolute maximum voltage of the IC chip is lower than the terminal voltage.
Innovation Solution
Incorporating resistive units with resistors, switches, and voltage regulators that generate a termination voltage lower than the supply voltage but higher than the reference voltage, such as zero volts, to mitigate voltage changes during mode switching, thereby reducing the risk of damage to connected IC chips.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a redriver switches between different operational modes, then the redriver can support multiple functions and improve adaptability, but an abrupt voltage change occurs at input/output terminals which can damage connected IC chips
Solution Approach 1:
The patent introduces a voltage regulator circuit as an intermediary component between the redriver's internal switching mechanisms and the external input/output terminals. This voltage regulator actively monitors and controls the terminal voltages, preventing abrupt changes when the redriver switches between operational modes. The intermediary absorbs the voltage transitions internally while maintaining stable external terminals, thus protecting connected IC chips without compromising the multi-mode functionality.
2Reliability
If a large capacitance decoupling capacitor is used to isolate DC levels, then the isolation effectiveness is improved, but the capacitance value causes abrupt voltage changes that can damage IC chips during mode switching
Solution Approach 1:
The patent implements a preliminary action by proactively controlling the voltage at input/output terminals before mode switching occurs. The voltage regulator is configured to detect upcoming mode transitions and preemptively adjust terminal voltages to avoid abrupt changes. This preliminary voltage management ensures that even with large decoupling capacitors present in the circuit, the IC chips are protected from damaging voltage transients during operational mode transitions.
3Object-affected harmful factors
If the termination voltage is set lower than the supply voltage, then the voltage change during switching is reduced protecting IC chips, but the voltage regulator complexity increases
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the termination voltage parameter to be lower than the main supply voltage. This voltage offset creates a voltage headroom that prevents abrupt terminal voltage changes during mode switching. The voltage regulator circuit, while adding some complexity, implements this parameter change through a controlled voltage reference and regulation stage that maintains the reduced termination voltage across all operational modes, thereby protecting IC chips from voltage transients.
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 allows redrivers to switch between operational modes without causing abrupt voltage changes, ensuring the safety of IC chips and reducing current consumption, making it suitable for power-saving modes while maintaining signal integrity.
Implementation Method 1
a voltage regulator connected to the at least one switch and configured to generate a termination voltage for the at least one switch
Implementation Method 2
at least one resistor connected to an input/output terminal of the redriver
Implementation Method 3
an input/output terminal of a redriver is electrically connected to a decoupling capacitor with a large capacitance value, which can isolate the direct current (DC) level
Data Source
AI summary
Embodiments of redrivers and resistive units for redrivers are disclosed. In an embodiment, a resistive unit for a redriver includes at least one resistor connected to an input/output terminal of the redriver, at least one switch serially connected to the at least one resistor, and a voltage regulator connected to the at least one switch and configured to generate a termination voltage for the at least one switch. Instead of grounding the at least one resistor, using the voltage regulator can avoid large voltage jump at input/output terminals to keep connected devices safe.