Self-Biased Capacitive Feedback Voltage Generator
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Solution Overview
Problem
Low-power nonvolatile memory integrated circuits face challenges in generating multiple analog voltages efficiently, as existing solutions like bandgap voltage reference circuits consume static power and are limited to single output voltages, while capacitive dividers are sensitive to capacitor ratios and parasitic capacitance.
Innovation Solution
An active control method is introduced, where a conventional leg sets an initial correct voltage value, and a differential stage is placed in a metastable state, allowing self-tuning to maintain optimal operating point without DC current consumption, reducing reliance on precise capacitor ratios and minimizing power usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If bandgap voltage reference circuit is used, then reliable reference voltage is provided, but static power consumption occurs and only one output voltage is generated
Solution Approach 1:
The patent employs periodic switching of capacitors between reference voltage and output voltage during initialization phases, rather than continuous DC operation. The capacitive feedback stage periodically charges and discharges capacitors to establish voltage relationships, eliminating the need for continuous current flow and reducing static power consumption while maintaining reference reliability.
Solution Approach 2:
The patent replaces the traditional bandgap voltage reference circuit with a capacitive feedback stage that uses capacitive division ratios instead of resistive or transistive elements. This substitution eliminates the need for bias currents and associated power consumption, achieving reference voltage generation without static power draw.
2Use of energy by moving object
If capacitive divider is used in feedback loop, then power consumption is reduced, but output voltage becomes sensitive to capacitor ratio variations and parasitic capacitance
Solution Approach 1:
The patent implements a feedback mechanism where the output voltage is fed back through capacitive dividers to the input of the voltage generator. The feedback loop continuously adjusts the output to maintain the correct voltage relationship, compensating for capacitor ratio variations and parasitic capacitance effects. This feedback ensures accurate voltage generation despite component tolerances.
Solution Approach 2:
The voltage generator circuit self-adjusts its operation based on the feedback from the capacitive divider network. The circuit automatically compensates for its own errors and variations without external intervention, maintaining accurate output voltage levels despite manufacturing tolerances in capacitor values and parasitic effects.
3Adaptability or versatility
If multiple voltage levels are generated, then system versatility is improved, but power consumption and circuit complexity increase
Solution Approach 1:
The patent creates a universal voltage generation architecture where a single capacitive feedback stage can generate multiple voltage levels by selectively connecting different capacitive divider ratios. The same core circuit structure serves multiple functions by reconfiguring capacitor connections, eliminating the need for separate voltage reference circuits for each voltage level and reducing total power consumption.
Solution Approach 2:
The patent divides the voltage generation function into modular capacitive feedback stages, each capable of generating specific voltage levels. By segmenting the overall voltage generation task into multiple reusable modular stages with different capacitive ratios, the system can generate multiple voltage levels using the same basic circuit architecture, reducing overall complexity and power consumption compared to having separate circuits for each 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
This approach reduces static current drain, enhances accuracy in analog voltage generation, lowers power consumption, simplifies system architecture, enables more voltage levels within a given power budget, and allows for a smaller layout, while eliminating dependencies on large capacitors for precision ratios.
Implementation Method 1
the op amp shown at the right of the diagram drives the charge pump shown at the top left, to maintain the output at a level which is equal to the reference voltage Vref times the capacitive ratio
Implementation Method 2
the output voltage is directly dependent on the capacitor ratio, so process variation, geometric effects, and parasitic capacitance effects can all affect the output voltage
Data Source
AI summary
Analog voltage drain with reduced current drain is achieved by a new capacitive-divided feedback architecture. During the operational phase an op amp monitors a capacitively-divided fraction of the output voltage, and drives a current sink or source accordingly; during an initial phase the output is forced to the correct value by a different circuit, while the opamp is connected to self-tune itself in a way which removes DC offset effects.