Charge Pump Regulator Fixed-Frequency PWM Control
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Solution Overview
Problem
Existing charge-pump-type step-up power supply circuits face issues with noise-induced malfunctions due to indeterminate-frequency operation of large switches under light loads, which can affect adjacent logic circuits in semiconductor integrated circuits.
Innovation Solution
A power supply circuit with a charge pump and a regulator that uses series-parallel switching and PWM control based on detected output voltage levels to maintain a constant frequency for switch operation, preventing indeterminate-frequency noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the charge pump operates under light load conditions with indeterminate frequency switching, then the voltage boosting function is achieved, but noise is generated that can induce malfunctions in adjacent logic circuits
Solution Approach 1:
The patent applies periodic action by using a fixed-frequency clock signal to control the switching of the charge pump circuit. The clock signal operates at a predetermined frequency, ensuring that the switches SW1 to SW4 operate periodically rather than with indeterminate frequency. This periodic switching eliminates the noise problem caused by irregular switching frequencies while maintaining the voltage boosting function under light load conditions.
Solution Approach 2:
The patent implements feedback control through a regulator circuit that monitors the output voltage Vout and adjusts the switching control accordingly. The regulator detects whether the output voltage meets the target voltage level and provides feedback signals to control the charge pump switching. This feedback mechanism ensures stable voltage regulation while maintaining fixed-frequency operation, preventing noise-induced malfunctions in adjacent logic circuits.
2Power
If large switches are used to achieve low impedance for charging and discharging the boost capacitor, then the charging/discharging function is improved, but the device area increases and more adjacent elements are present
Solution Approach 1:
The patent uses periodic switching controlled by a fixed-frequency clock signal to optimize the charging and discharging operation of the boost capacitor. By operating at a predetermined frequency, the switches can be designed with smaller dimensions while still achieving the required charging/discharging capability. The periodic action allows for optimized timing that reduces the need for large switch sizes.
Solution Approach 2:
The patent changes the operating parameters of the switches by controlling them with a fixed-frequency clock signal and optimized duty cycles. This parameter optimization allows the switches to achieve low impedance during their ON state without requiring large physical dimensions. The controlled switching parameters enable smaller switch areas while maintaining the necessary power handling capability.
3Adaptability or versatility
If the switches operate at indeterminate frequency under light load, then the voltage regulation adapts to load conditions, but noise is generated that affects adjacent logic circuits
Solution Approach 1:
The patent maintains adaptability to load conditions while eliminating noise by using periodic switching at a fixed frequency. The clock signal operates at a predetermined frequency regardless of load conditions, ensuring that the switching action remains periodic and noise-free. The adaptability is achieved through feedback control that adjusts the duty cycle or switching control based on load requirements, while the frequency remains fixed to prevent noise.
Solution Approach 2:
The regulator circuit provides feedback control that adapts the charge pump operation to varying load conditions while maintaining fixed-frequency switching. The feedback mechanism monitors the output voltage and adjusts the switching control parameters (such as duty cycle or enable signals) to match load demands, while the underlying clock frequency remains constant. This ensures both load adaptability and noise-free operation.
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 solution ensures that switches operate at a determined frequency, preventing noise-induced malfunctions in adjacent logic circuits and maintaining stable voltage regulation across varying load conditions.
Implementation Method 1
a charge pump that connects a capacitor to a DC supply voltage by series-parallel switching, thereby boosting the DC supply voltage by a voltage to which the capacitor is charged
Implementation Method 2
a regulator that controls negative feedback of output voltage of the charge pump to a target voltage
Data Source
AI summary
Boosting operation of a charge pump is performed at a fixed period irrespective of the state of a load. A regulator for controlling a charge pump includes: a frequency dividing circuit generating a frequency-divided clock having a period that is twice that of a boost clock; a voltage dividing circuit generating a plurality of divided voltages having voltage values that differ from one another; a comparator circuit comparing each of the divided voltages and a reference voltage and outputting a plurality of comparison-result signals; a selection signal generating circuit reading in logic of each of the comparison-result signals in synch with an edge of the frequency-divided clock and outputting selection signals; a duty converting circuit outputting a plurality of clocks having different ON duties; a selector selecting any one of the plurality of clocks or “H”-level logic as a PWM signal based upon the selection signals; and a gate circuit taking the logical AND between the frequency-divided clock and the PWM signal and generating control signals for controlling series-parallel switching.