Switched-Capacitor Ripple Cancellation Using Mirrored Current Pulses
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Solution Overview
Problem
Switched-capacitor circuits generate current pulses that cause ripples on voltage lines, degrading the performance of other circuits due to limited bandwidth of voltage regulators, and increasing load capacitance negatively impacts stability while increasing power consumption.
Innovation Solution
A ripple-cancellation circuit is introduced that injects current pulses into the voltage line to cancel out the current pulses from the switched-capacitor circuit, using a current mirror and switching circuit to synchronize and scale the current pulses, thereby reducing the ripple on the voltage line.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If load capacitance is increased to reduce ripple, then ripple reduction is achieved, but stability deteriorates and power consumption increases
Solution Approach 1:
The ripple cancellation circuit proactively generates a counter-current pulse in response to the switching signal before the ripple can significantly impact the voltage line. This preliminary anti-action neutralizes the harmful current pulses from the switched-capacitor circuit, reducing ripple without requiring increased load capacitance that would compromise stability.
Solution Approach 2:
The ripple cancellation circuit acts as an intermediary between the switched-capacitor circuit and the voltage line. It receives the switching signal and generates compensating current pulses that are injected into the voltage line, mediating the interaction between the switching circuit and the power delivery network to eliminate ripple while maintaining stability.
2Object-affected harmful factors
If load capacitance is increased to reduce ripple, then ripple reduction is achieved, but power consumption increases
Solution Approach 1:
The circuit generates counter-current pulses in response to switching edges, proactively neutralizing ripple-causing current pulses. This approach eliminates ripple without relying on large load capacitance, thereby avoiding the increased power consumption that would result from charging and discharging larger capacitors.
Solution Approach 2:
The ripple cancellation circuit dynamically adjusts the timing and magnitude of counter-current pulses based on the switching signal characteristics. By changing the temporal parameters of current injection rather than increasing capacitance values, the circuit achieves ripple reduction with minimal impact on power consumption.
3Device complexity
If bandwidth of voltage regulator is limited, then circuit complexity is reduced, but ability to suppress ripple deteriorates
Solution Approach 1:
The ripple cancellation circuit serves as an intermediary that handles ripple suppression independently of the voltage regulator. It injects compensating current pulses directly onto the voltage line, performing the ripple suppression function without requiring the voltage regulator to have high bandwidth, thus maintaining simple regulator design while achieving effective ripple suppression.
Solution Approach 2:
The ripple suppression function is segmented from the voltage regulation function. The ripple cancellation circuit handles high-frequency ripple suppression through targeted current pulse injection, while the voltage regulator maintains its simpler design focused on DC voltage regulation, allowing each component to operate within its optimal bandwidth without requiring complex high-bandwidth regulation.
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 effectively reduces the ripple on the voltage line, improving the stability of voltage regulators without increasing power consumption, by synchronizing and scaling current pulses to match those from the switched-capacitor circuit.
Implementation Method 1
a current mirror having a first branch and a second branch, wherein the second branch of the current mirror is coupled to the voltage line
Implementation Method 2
A switched-capacitor circuit includes one or more capacitors and switches configured to transfer charge to and from the one or more capacitors
Data Source
AI summary
In certain aspects, a system includes a voltage line, a switched-capacitor circuit coupled to the voltage line, and a ripple-cancellation circuit. The ripple-cancellation circuit includes a current mirror having a first branch and a second branch, wherein the second branch of the current mirror is coupled to the voltage line, a switching circuit having a first terminal, a second terminal, and a third terminal, wherein the first terminal of the switching circuit is coupled to the first branch of the current mirror, and the third terminal is coupled to a ground or a reference voltage, and a first capacitor coupled to the second terminal of the switching circuit.