Self-Oscillating Charge Pump Frequency Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing integrated circuit charge pump circuits are inefficient in terms of power consumption and chip area usage, with high ripple voltage causing noise in operational amplifiers and requiring large flying capacitors that waste energy during switching transitions.
Innovation Solution
A self-oscillating charge pump circuit that compares the bottom plate voltages of flying capacitors to a reference value using a comparator and flip-flop to determine a swapping frequency that prevents current source saturation, minimizing the frequency of capacitor swapping and reducing power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a conventional charge pump circuit uses external oscillator to control capacitor swapping, then the circuit can operate at fixed frequency, but the power consumption increases and chip area expands
Solution Approach 1:
The charge pump circuit uses its own output voltage to control the capacitor swapping through an automatic level detector and monostable multivibrator, eliminating the need for external oscillator and reducing power consumption while maintaining optimal operation
Solution Approach 2:
The circuit incorporates feedback mechanisms where the output voltage level is detected and used to automatically control the swapping frequency, ensuring the circuit operates at the minimum necessary frequency to prevent current source saturation
2Object-affected harmful factors
If the flying capacitors are made large to reduce ripple voltage, then the noise performance improves, but the chip area required increases
Solution Approach 1:
The circuit implements periodic swapping of flying capacitors at optimized intervals, allowing smaller capacitor values to achieve the same ripple reduction effect that would require larger capacitors in continuous operation
Solution Approach 2:
The capacitor swapping frequency is dynamically adjusted based on the output voltage level, allowing the circuit to operate at minimum necessary frequency while maintaining low ripple and noise performance
3Reliability
If the capacitor swapping frequency is increased to prevent current source saturation, then the reliability improves, but the power consumption increases
Solution Approach 1:
The circuit automatically detects when current source saturation is approaching by monitoring output voltage level and adjusts swapping frequency accordingly, ensuring reliable operation at minimum necessary frequency
Solution Approach 2:
The circuit changes the swapping frequency parameter dynamically based on operating conditions, increasing frequency only when necessary to prevent saturation and maintaining lower frequency during normal operation to reduce power consumption
Data Source
AI summary
Charge pump circuitry (30) compares bottom plate voltages of first (C1) and second (C2) flying capacitors in a current mode charge pump (1B) to a reference value (VDD−V28) by means of a comparator (20) which drives a flip-flop (22) that generates first (F1) and second (F2) complementary phase signals. The first and second phase signals control switching of the flying capacitors to determine a flying capacitor swapping frequency just low enough to prevent saturation of a discharge current source (10) that discharges the flying capacitors into an output conductor (3).