Cascoded Level Shifter With Reference Voltage Perturbation
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Solution Overview
Problem
Cascoded level shifters face stress and reduced component lifetime due to excessive voltage differences during signal transitions, particularly in smaller technology scales where power consumption and compatibility with higher voltage domains are concerns.
Innovation Solution
Incorporation of reference voltage perturbation circuitry, such as capacitors and resistors, to cause transient perturbations in the reference voltage, ensuring cascode switches activate earlier and avoid overstress, with additional capacitors to limit the duration of the boost and prevent prolonged voltage overstress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If level shifter operates at higher voltage to interface with higher voltage domains, then compatibility with older devices and protocols is improved, but components in lower voltage domain are exposed to excessive voltage differences causing overstress and reduced lifetime
Solution Approach 1:
The patent applies preliminary action by boosting the reference voltage before the cascode switch needs to turn on during signal transitions. This is achieved by detecting the input signal transition and activating a capacitor to temporarily increase the reference voltage, which causes the cascode switch to turn on earlier than it would normally, preventing excessive voltage stress before it occurs
Solution Approach 2:
The patent changes the reference voltage parameter dynamically during transitions. By temporarily increasing the reference voltage level during critical transition periods through capacitor coupling, the operating parameters of the cascode switch are modified to prevent overstress, while returning to normal operating parameters when transitions are complete
2Loss of energy
If cascode switch turns on later during transitions, then DC power consumption is reduced, but transient voltage stress on components increases during signal transitions
Solution Approach 1:
The patent applies periodic action by using transient, periodic voltage boosting only during necessary transition periods rather than continuously. The capacitor-based circuit activates temporarily during input signal transitions to boost the reference voltage, then returns to normal operation, providing protection only when needed while maintaining low DC power consumption during steady-state operation
Solution Approach 2:
The patent applies preliminary anti-action by preemptively countering the harmful transient voltage stress through reference voltage boosting before the stress can occur. The circuit detects transitions and activates the capacitor to create an opposing effect that prevents the harmful voltage differential from developing across the cascode switch
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
Enhances the durability and reliability of cascoded level shifters by preventing voltage overstress during transitions without increasing DC power consumption, ensuring efficient operation across voltage domains.
Implementation Method 1
In a first example embodiment, the reference voltage perturbation circuitry comprises a capacitor connecting the reference node to the input node
Data Source
AI summary
A cascoded level shifter for receiving an input signal in a low voltage range and for generating an output signal in a high voltage range is disclosed. The cascoded level shifter is subdivided into a first voltage section and a second voltage section, the first voltage section having a lower voltage supply than the second voltage section, and a combined voltage across the first voltage section and the second voltage section corresponding to the high voltage range, the cascoded level shifter comprising: an input node configured to receive an input signal; a cascoded device disposed in one of the first voltage section and the second voltage section, the cascoded device comprising a driver switch connected in series with a cascode switch at a midpoint node, the cascode switch switching in dependence on a reference voltage of a reference node and the input signal; and reference voltage perturbation circuitry, configured to cause a transient perturbation to the reference voltage in response to a transition of the input signal to cause the cascode switch to switch.