Switched Capacitor Regulator Slew Rate Control
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Solution Overview
Problem
Switched capacitor regulators face challenges in regulating output voltage without adjusting switching frequency, which is prohibitive due to electromagnetic interference (EMI) concerns in sensitive electronic devices like mobile phones.
Innovation Solution
The solution involves using circuits with variable slew rates on control signals of power switches to adjust the effective resistance of power switches, allowing for output regulation without changing switching frequency, by employing PMOS and NMOS FET switches and varying capacitance and current sources to control gate drive signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If switching frequency is adjusted to regulate output voltage, then output voltage regulation is achieved, but electromagnetic interference increases
Solution Approach 1:
The patent changes the parameter being adjusted from switching frequency to slew rate of gate control signals. By varying the slew rate (rate of change of voltage) of the gate control signals while maintaining constant switching frequency, the patent achieves output voltage regulation without changing the switching frequency, thus avoiding EMI issues.
2Object-generated harmful factors
If switching frequency is kept constant to reduce EMI, then electromagnetic interference is reduced, but output voltage regulation becomes difficult
Solution Approach 1:
The patent substitutes the adjustable parameter from switching frequency to slew rate. By keeping switching frequency constant and instead adjusting the slew rate of gate control signals, the patent maintains low EMI while achieving output voltage regulation through the effective resistance change of power switches.
3Measurement precision
If slew rate of control signals is varied to regulate output, then output voltage regulation is achieved without changing switching frequency, but circuit complexity increases
Solution Approach 1:
The patent introduces slew rate control circuits as intermediary components between the control signal source and the power switch gates. These intermediary circuits (including capacitors and resistors) shape the gate control signals to have variable slew rates, enabling voltage regulation without direct frequency modulation of the switching signal.
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 enables effective regulation of output voltage or current while maintaining a predictable switching frequency, reducing EMI and ensuring stable operation in sensitive electronic devices.
Implementation Method 1
a first capacitor having a first side and a second side
Data Source
AI summary
Circuits comprising: a first capacitor(C1); a first switch(S1) having a first side coupled to a VIN and a second side coupled to a first side of C1; a second switch(S2) having a first side coupled to the second side of S1; a third switch(S3) having a first side coupled to a second side of S2 and a second side coupled to a second side of C1; a fourth switch(S4) having a first side coupled to a second side of S3 and a second side coupled to a VSUPPLY, wherein: in a first state, S1 and S3 are off, and S2 and S4 are on; in a second state, S1 and S3 are on, and S2 and S4 are off; and at least one of a control of S1, a control of S2, a control of S3, and a control of S4 is coupled to a time-varying-slew-rate signal.