Charge-Pump Feedback Loop Reduces Current Drain
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Solution Overview
Problem
High voltage charge-pumps used in MEMS switches for wireless communication devices face significant current drain and large die area issues due to resistive divider loads in feedback control loops, which are inefficient and occupy substantial space.
Innovation Solution
A novel feedback control loop using a sensing charge-pump replaces the resistive divider, reducing current drain and die area by incorporating a Dickson charge-pump with a sensing charge-pump stage that samples voltage levels and adjusts clock signals to maintain output voltage within specified ranges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a resistive divider load is used in the feedback control loop, then the output voltage can be detected and controlled, but the current drain increases and the die area increases
Solution Approach 1:
The patent extracts the voltage detection function from the resistive divider load and relocates it to a dedicated voltage detector circuit. This separation allows the resistive divider to be optimized for voltage sampling while the detector handles the control signal generation, reducing the overall current drain and die area requirements
Solution Approach 2:
The voltage detector circuit serves multiple functions: it detects the divided voltage, compares it with the reference voltage, generates the control signal for the VCO, and regulates the output voltage. This multi-functionality eliminates the need for separate components, reducing die area and current drain
2Reliability
If a resistive divider load is used in the feedback control loop, then the output voltage can be detected and controlled, but the die area increases
Solution Approach 1:
The patent merges the voltage detection, reference voltage comparison, and control signal generation functions into a single integrated voltage detector circuit. This consolidation reduces the number of discrete components and interconnections, thereby reducing the overall die area while maintaining output voltage control reliability
Solution Approach 2:
The voltage detector circuit performs multiple functions including voltage detection, comparison with reference voltage, and control signal generation. This multi-functionality allows a single compact circuit to replace what would otherwise require multiple separate components, reducing die area
3Reliability
If high voltage transistors are used to block current discharge, then the current discharge is blocked, but the device complexity and die area increase
Solution Approach 1:
The patent removes the high voltage transistor from the circuit by implementing a feedback control mechanism that naturally prevents current discharge. The voltage detector monitors the output voltage and adjusts the VCO frequency to maintain proper voltage levels, eliminating the need for active current blocking components
Solution Approach 2:
The feedback control loop serves the function of preventing current discharge through self-regulation. When the output voltage approaches maximum levels, the detector reduces the VCO frequency, which reduces the charge pump current, thereby self-limiting the current discharge without requiring external blocking components
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 current drain by half and minimizes die area, maintaining stable output voltage with reduced parasitic capacitance and increased loop stability, while eliminating the need for high voltage transistors that block current discharge.
Implementation Method 1
The Dickson charge-pump is made up of a plurality of voltage boosting stages, each stage comprising a diode, a capacitor having a first end coupled to an anode of the diode, and a second end driven by a clock signal
Implementation Method 2
The sensing charge-pump has at least one voltage sensing stage that is communicably coupled to at least one of the plurality of voltage boosting stages
Implementation Method 3
A voltage controlled oscillator (VCO) having a voltage error input coupled to the voltage error output and a variable frequency output
Data Source
AI summary
A high voltage charge-pump includes a plurality of voltage boosting stages, a low voltage input, and at least one clock input. A sensing charge-pump having a voltage detector output has at least one voltage sensing stage that is communicably coupled to at least one of the plurality of voltage boosting stages. A loop filter in a feedback control loop includes a voltage detector input coupled to the voltage detector output, a voltage reference input, and a voltage error output. A voltage controlled oscillator (VCO) with a variable frequency output has a voltage error input coupled to the voltage error output. The feedback control loop also includes at least one driver having a variable frequency input coupled to the variable frequency output and at least one clock output coupled to the at least one clock input.