Charge Pump Ramp-Rate Control Using Variable Capacitance Feedback
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Solution Overview
Problem
Existing charge pumps for non-volatile memories face challenges in precisely controlling the ramp rate due to variability in load capacitance and current, leading to inefficiencies in power consumption and die area usage, making it difficult to achieve consistent voltage regulation across different operating conditions.
Innovation Solution
A charge pump system that includes a counter, digital-to-analog converter, comparator, and variable capacitor, which dynamically adjusts capacitance based on real-time comparisons to maintain a desired ramp rate, allowing for independent control of the output voltage ramp-up process by increasing or decreasing capacitance as needed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a shunt current is used to control the ramp rate, then the ramp rate can be controlled, but power consumption increases and some charge is lost
Solution Approach 1:
The patent implements a feedback mechanism where the actual ramp rate is measured and compared to a desired ramp rate, and the charging capacitor size is dynamically adjusted based on the error signal to achieve precise control without continuous shunt current
Solution Approach 2:
The patent changes the physical parameter of capacitor size dynamically during operation to control the ramp rate. By adjusting the charging capacitor size based on load conditions, the system achieves precise ramp rate control without the continuous power loss associated with shunt currents
2Measurement precision
If the charging capacitor size is adjusted to control the ramp rate, then the ramp rate can be modulated, but the control is complicated by load variability
Solution Approach 1:
The system uses feedback to automatically adjust the charging capacitor size based on the actual ramp rate and load conditions, eliminating the need for complex manual control and adapting to variable loads automatically
Solution Approach 2:
The patent makes the charging capacitor size dynamic rather than fixed, allowing it to adapt to changing load conditions. This dynamic adjustment simplifies control by letting the system self-regulate rather than requiring complex external control mechanisms
3Stability of the object's composition
If a large smoothing capacitor is selected to swamp load variability, then ramp rate consistency is improved, but die area and power consumption increase
Solution Approach 1:
The patent uses dynamic adjustment of the charging capacitor size to maintain ramp rate consistency without requiring a large fixed smoothing capacitor. This dynamic approach allows the system to adapt to load changes while using minimal capacitor area
Solution Approach 2:
By changing the charging capacitor size parameter dynamically based on load conditions, the system achieves ramp rate consistency without the need for a large fixed capacitor, thereby reducing die area while maintaining stability
4Area of stationary object
If the charging capacitor size is reduced to decrease die area, then the ramp rate becomes sensitive to load changes, but precise control becomes difficult
Solution Approach 1:
The feedback mechanism continuously monitors the ramp rate and adjusts the charging capacitor size to compensate for load changes, maintaining precise control even with a small capacitor that would otherwise be highly sensitive to load variations
Data Source
AI summary
A charge pump includes a first counter and a pump stage. The first counter has a control input for receiving a control signal, and an output for providing a first count value. The first count value is incremented in response to the control signal being a first logic state and the first count value is decremented in response to the control signal being a second logic state. The pump stage has a variable capacitor. The variable capacitor has a control input coupled to the output of the first counter for receiving the first count value. The capacitance value of the variable capacitor is changed in response to the first count value changing. The capacitance value is for determining a ramp-up rate of an output voltage at an output of the charge pump.