Charge Pump Circuit Synchronization to Prevent EMI Noise
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Solution Overview
Problem
Conventional charge pump circuits generate EMI noise of frequency components independent of the operation clock frequency when transitioning from a disable to an enable state, causing interference in integrated circuits, particularly in audio devices.
Innovation Solution
A charge pump circuit design that includes a level detection circuit, an oscillator circuit, and a detection signal synchronization circuit, where capacitive elements are charged and discharged in synchronization with the clock signal and synchronization detection signal, preventing asynchronous operations and thus reducing EMI noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the charge pump circuit changes from disable state to enable state, then the circuit becomes operational and generates boosted voltage, but EMI noise of frequency component independent of operation clock frequency occurs
Solution Approach 1:
The patent applies preliminary action by introducing a start signal that is generated in advance and synchronized with the clock signal before the charge pump circuit begins operation. This start signal pre-configures the circuit state and ensures that all switching operations occur only at clock signal edges, preventing asynchronous transitions that generate EMI noise. The level detection circuit detects the boosted voltage level beforehand and controls the start signal timing to align with clock cycles.
2Productivity
If the charge pump circuit operates at high frequency, then productivity is improved, but EMI noise radiation increases
Solution Approach 1:
The patent implements periodic action by ensuring that all charge pump operations are strictly synchronized to the clock signal period. The start signal and level detection circuit work together to enable circuit operation only at specific clock edges, creating a regular periodic pattern of operation. This periodic synchronization ensures that current consumption and EMI noise occur at predictable, clock-related frequencies rather than generating independent frequency components, allowing high-frequency operation without excessive EMI radiation.
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 synchronizes the operation of the charge pump circuit with the clock signal, preventing EMI noise of frequency components independent of the operation clock frequency, thereby minimizing interference and consumption current peaks.
Implementation Method 1
a plurality of charge transfer elements coupled in series and a plurality of capacitive elements each coupled to a coupling path between adjacent charge transfer elements, which boosts an external power supply voltage supplied from an external power supply to the charge transfer elements by charging and discharging adjacent capacitive elements alternately
Data Source
AI summary
There is provided a charge pump circuit which can prevent EMI noise of a frequency component independent of an operation clock frequency from occurring at the time of a change from a disable state to an enable state. The charge pump circuit includes a detection signal synchronization circuit which outputs a synchronization detection signal generated by synchronizing a detection signal outputted from a level detection circuit to a clock signal outputted from an oscillator circuit. The synchronization detection signal is used as a pump enable signal, and a first pump capacitance and a second pump capacitance in a pump circuit body are charged and discharged in response to the synchronization detection signal and the clock signal outputted from the oscillator circuit.