Charge Pump Circuit Negative Voltage Generation Feedback Loop
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Solution Overview
Problem
Existing negative voltage generation circuits for RF switches, such as those used in RF silicon-on-insulator (SOI) switches, face inefficiencies and increased spurious signals due to control being performed in the negative supply domain, leading to higher current consumption and longer start-up times, particularly when generating adjustable negative voltages for NMOS switching devices.
Innovation Solution
A charge pump circuit with a switched capacitor voltage inverter and a feedback loop, utilizing a clock generator and operational amplifier to generate a negative voltage, which includes a maximum charging supply voltage during open-loop start-up and transitions to closed-loop regulation, along with a filter to minimize spurious emissions and improve start-up speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If control is performed in the negative supply domain to generate adjustable negative voltage, then the negative voltage is generated, but current consumption increases and spurious signals increase
Solution Approach 1:
The patent implements a feedback loop where the negative voltage output is sensed and fed back to the clock generator. The clock generator adjusts the clock signal frequency based on the feedback voltage to regulate the negative voltage output. This closed-loop control enables adjustable negative voltage generation while maintaining low current consumption by optimizing the charge pump operation based on actual output conditions.
2Adaptability or versatility
If control is performed in the negative supply domain to generate adjustable negative voltage, then the negative voltage is generated, but spurious signals increase
Solution Approach 1:
The feedback mechanism senses the negative voltage output and adjusts the clock frequency accordingly. This regulation minimizes spurious signals by maintaining optimal operating conditions and reducing ripple and noise in the negative voltage output through dynamic adjustment of the charge pump switching frequency.
3Object-generated harmful factors
If a filter is added to minimize spurious emissions, then spurious signals are reduced, but device complexity increases
Solution Approach 1:
The patent uses a feedback-based voltage sensing mechanism that requires minimal additional circuitry. The feedback path includes a voltage divider and comparator that sense the negative voltage and adjust the clock frequency, providing spurious signal reduction without requiring complex filtering networks or additional regulation stages.
4Loss of time
If open-loop start-up with maximum charging supply voltage is used, then start-up time is reduced, but voltage regulation accuracy decreases
Solution Approach 1:
The patent implements a two-stage start-up sequence: first, an open-loop phase with maximum charging voltage rapidly charges the capacitive elements to establish negative voltage output quickly; second, a closed-loop phase where the feedback mechanism engages to regulate the voltage to the precise target value. This preliminary rapid charging followed by regulated adjustment minimizes both start-up time and voltage regulation error.
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 reduces start-up time and improves efficiency by using a feedback loop and filter to stabilize and regulate the negative voltage generation, minimizing spurious signals and allowing for programmable control of the negative voltage output.
Implementation Method 1
a switched capacitor voltage inverter circuit comprising a plurality of capacitive elements wherein the switched capacitor voltage inverter circuit is arranged to receive the at least one clock signal and generate a negative voltage therefrom
Data Source
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AI summary
A charge pump circuit for generating a negative voltage has: a clock generator arranged to output at least one clock signal; a switched capacitor voltage inverter circuit including capacitive elements wherein the switched capacitor voltage inverter circuit receives the at least one clock signal and generates a negative voltage therefrom. The charge pump circuit further has a regulation control loop providing a feedback path from an output of the switched capacitor voltage inverter circuit to a supply input of the switched capacitor voltage inverter circuit, and an output arranged to output a generated negative voltage. The feedback path has an operational amplifier configured to generate a maximum charging supply voltage from a fed back level-shifted negative voltage and apply the maximum charging supply voltage to the input supply of the switched capacitor voltage inverter to charge at least one of the capacitive elements during a loop start up.