Programmable Slew Rate Power Switch Glitch Reduction
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Solution Overview
Problem
Existing digital voltage supply switches for increasing power supply voltage are sensitive to process parameters, temperature, and output load, and require a clock, resulting in an inefficient staircase voltage output.
Innovation Solution
An apparatus with a Ramp-Up Control circuit using an amplifier and glitch filter to provide a programmable linear slew rate for the output voltage, stabilized by a capacitor and voltage sensor, minimizing glitches and ensuring a smooth voltage ramp-up.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a digital approach with counter and decoder is used to control power transistor switching, then a specific voltage output slew rate is achieved, but the implementation becomes very sensitive to process parameters, temperature, output load and resistive network variations
Solution Approach 1:
The patent replaces the digital control system (counter, decoder, clock) with an analog control system using an operational amplifier, capacitor, and resistive network. This substitution eliminates the staircase voltage profile and clock dependency, providing continuous voltage ramping that is less sensitive to process variations and temperature changes.
Solution Approach 2:
The patent changes the control parameters from digital switching signals to analog voltage signals generated by the operational amplifier. The voltage ramp rate is controlled by the RC time constant (R×C) of the resistive network and capacitor, allowing precise control of the slew rate while maintaining stability against process and temperature variations.
2Speed
If multiple power transistors are switched on successively in discrete steps, then a target peak voltage is reached, but the voltage output profile has a staircase shape instead of a smooth ramp
Solution Approach 1:
The patent implements continuous voltage ramping by using an operational amplifier that continuously adjusts the gate voltage of the power transistor. The capacitor charges continuously through the resistive network, creating a smooth linear voltage increase rather than discrete steps, thus eliminating the staircase effect while maintaining controlled ramp-up speed.
3Ease of operation
If a digital voltage supply switch is used, then voltage ramp-up can be controlled, but the circuit requires a clock signal and becomes complex
Solution Approach 1:
The patent extracts and removes the clock signal requirement from the voltage ramp-up control circuit. The operational amplifier-based analog control system generates the necessary control signals internally through RC timing, eliminating the need for an external clock and associated digital control logic, thus simplifying the overall circuit.
4Speed
If rapid voltage switching is performed, then voltage ramp-up is achieved, but glitches and current stress occur in the output voltage
Solution Approach 1:
The patent applies beforehand cushioning by using a capacitor in the control circuit that smooths the voltage transitions. The capacitor charges gradually through the resistive network, preventing abrupt voltage changes and reducing glitches and current stress before they can occur in the output voltage.
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 achieves a stable and smooth linear voltage ramp-up with reduced sensitivity to environmental factors and load variations, providing accurate and efficient voltage supply with minimal glitches.
Implementation Method 1
a capacitor CC that is coupled to the first port, wherein selection of one or more of the selectable mirrored current mirrors and a capacitance value for the capacitor CC results in the selected linear slew rate
Implementation Method 2
an amplifier that receives the output of a plurality of selectable mirrored current sources for programming a selected linear slew rate for the increasing output voltage
Implementation Method 3
a glitch filter circuit for stabilizing the increasing output voltage so as to minimize glitches, including current and voltage stress, in the output voltage
Data Source
AI summary
An apparatus is configured to provide a voltage rising at the output with a programmable slew rate. The apparatus comprises a ramp-up control circuit module for supplying an increasing output voltage that is output to a load circuit. The ramp-up control circuit comprises an amplifier that receives the output of a plurality of selectable mirrored current sources that build up voltage across a capacitor for programming a selected linear slew rate for the increasing output voltage. The apparatus further comprises a glitch filter circuit for stabilizing the increasing output voltage so as to minimize glitches, including current and voltage stress, in the output voltage.