Voltage Generator Ramp Rate Control Circuit
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Solution Overview
Problem
Voltage generators in semiconductor devices face challenges in quickly providing desired voltages while minimizing high ripple, which can introduce noise and affect transistor reliability.
Innovation Solution
A voltage generator design featuring a high ramp rate initially followed by a variable ramp rate, utilizing a comparator and an amplifier with different gain levels, and a voltage controlled oscillator to manage frequency transitions, ensuring rapid voltage attainment with low ripple.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a voltage generator operates at high frequency to quickly provide desired voltage, then the voltage delivery speed is improved, but the ripple increases introducing noise
Solution Approach 1:
The system dynamically switches between two operating modes: a first mode with high ramp rate for quick voltage delivery, and a second mode with lower ramp rate for low ripple operation. The control circuit transitions between modes based on whether the output voltage has reached the target voltage, allowing the system to optimize between speed and ripple minimization at different operational stages.
Solution Approach 2:
The voltage generation process is segmented into two distinct phases: an initial phase using a first charge pump circuit with high ramp rate to quickly reach the target voltage, and a subsequent phase using a second charge pump circuit with lower ramp rate to maintain the voltage with minimal ripple. This segmentation allows each phase to be optimized for its specific function.
2Loss of time
If a voltage generator uses high ramp rate to achieve quick voltage attainment, then the response time is improved, but the ripple increases affecting system stability
Solution Approach 1:
The control circuit dynamically adjusts the operating mode based on real-time voltage feedback. When the output voltage is below the target voltage, the system operates in the first mode with high ramp rate for fast response. Once the target voltage is reached, the system transitions to the second mode with lower ramp rate to minimize ripple and maintain stability, thus optimizing both response time and system stability throughout the voltage generation process.
Solution Approach 2:
The system employs periodic switching between two charge pump circuits with different ramp rates. The first charge pump circuit operates periodically to quickly charge the output capacitor, while the second charge pump circuit operates periodically at a lower rate to maintain the voltage with minimal ripple, creating a periodic action pattern that balances speed and stability.
Data Source
AI summary
A charge pump system includes a comparator having a first input coupled to a first reference voltage, a second input coupled to a feedback signal and an output coupled to control operation of a voltage controlled oscillator. The feedback signal is coupled to an output of the charge pump system. An amplifier has a first input coupled to a second reference voltage, a second input coupled to the feedback signal, and an output coupled as input to the voltage controlled oscillator. A gain of the amplifier is lower than a gain of the comparator.