Charge Pump Bias Voltage Generator for Output Ripple Reduction
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Solution Overview
Problem
Conventional charge pump booster circuits experience undesired voltage ripples due to fluctuations in load current, particularly when capacitance is limited by chip size, leading to instability in output voltage.
Innovation Solution
Incorporating a bias voltage generator to compare the output voltage with a reference voltage and provide a bias voltage to the charge pump circuits, along with a ring oscillator and decoupling capacitors, to stabilize the output voltage by controlling the slew rate drivers and transistors, thereby managing voltage fluctuations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the decoupling capacitor capacitance is increased to reduce voltage ripples, then the output voltage stability is improved, but the chip size increases
Solution Approach 1:
The patent changes the operating parameters of the charge pump circuit by dynamically adjusting the clock signal frequency and duty cycle based on load conditions. The controller monitors output voltage and adjusts the charge pump operation to maintain stability without requiring large decoupling capacitors, thus resolving the contradiction between voltage stability and chip size
Solution Approach 2:
The patent implements a feedback control mechanism where the output voltage is continuously monitored and used to adjust the charge pump operation. The controller compares the output voltage with a reference voltage and adjusts the clock signal parameters accordingly, enabling stable output voltage without large decoupling capacitors
2Stability of the object's composition
If the charge pump switching frequency is increased to improve response to load changes, then the output voltage stability is improved, but the power consumption increases
Solution Approach 1:
The patent employs dynamic adjustment of the charge pump clock signal frequency and duty cycle based on real-time load conditions. The controller increases switching frequency only when load changes detect voltage fluctuations, and reduces frequency during steady-state operation, thereby maintaining voltage stability while minimizing power consumption
Solution Approach 2:
The patent uses periodic charge pump switching with variable frequency and duty cycle. The controller applies periodic control signals to the charge pump, adjusting the period and pulse width dynamically based on load conditions, achieving efficient voltage regulation with optimized power consumption
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
The solution effectively reduces voltage ripples and stabilizes the output voltage across clock cycles, ensuring a more stable and efficient operation by dynamically adjusting the bias voltage based on output voltage fluctuations.
Implementation Method 1
A capacitor CL 14 is a decoupling capacitor coupled between a ground level VSS and an output terminal of the conventional charge pump booster circuit 1. The capacitor CL 14 receives and accumulates charge from the plurality of charge pump circuits 13a and 13b and provide the output voltage VOUT during a charging interval
Implementation Method 2
The slew rate driver 15a is a p-channel field effect transistor for a transition from a logic low state to a logic high state. The slew rate driver 15b is an n-channel field effect transistor for a transition from a logic high state to a logic low state
Data Source
AI summary
An apparatus and a method that provide a bias voltage to a charge pump circuit are described. An example apparatus includes: a bias voltage generator that receives a first voltage and provides a second voltage responsive to the first voltage; a charge pump circuit that receives an input signal and provides the first voltage. The charge pump circuit includes an inverter and a bias transistor. The inverter receives the input signal and provides a third voltage. The bias transistor coupled between a power node having a power supply voltage and a slew rate driver of the inverter. The bias transistor receives the second voltage and provides a power supply voltage to the slew rate driver responsive to the second voltage less than a threshold voltage and stops providing the power supply voltage to the slew rate driver responsive to the second voltage greater than the threshold voltage.