Charge Pump Circuit Fast Start-Up via Multi-Phase Clocking
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Solution Overview
Problem
Charge pump circuits face challenges in reducing the time required for the output voltage to reach a target value, as increasing clock frequency leads to electromagnetic compatibility issues and increasing capacitance increases the circuit area, making it difficult to achieve rapid voltage stabilization.
Innovation Solution
The introduction of a bypass circuit coupled with an m-phase clock generator that multiplies the clock frequency during start-up, allowing multiple pump capacitors to be charged simultaneously, thereby increasing the amplitude of voltage steps and reducing the ramp-up time without increasing the circuit area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If the clock frequency is increased to reduce the ramp-up time, then the time for output voltage to reach target value is reduced, but electromagnetic compatibility and electromagnetic interference effects worsen
Solution Approach 1:
The charge pump circuit is divided into multiple pump unit cells (first plurality and second plurality) that operate in parallel with different clock phases. This segmentation allows the circuit to achieve faster voltage ramp-up through multiple simultaneous charging paths without requiring a single high-frequency clock signal, thereby reducing electromagnetic interference while maintaining fast start-up performance.
2Loss of time
If the capacitance of each pump capacitor is increased to reduce the ramp-up time, then the time for output voltage to reach target value is reduced, but the area of the charge pump circuit increases
Solution Approach 1:
Multiple pump unit cells are merged into parallel configurations, where each unit cell contributes to the overall voltage generation. This merging allows the circuit to achieve faster ramp-up times through combined charging capacity without requiring individual capacitors to be oversized, thus maintaining compact circuit area while improving start-up speed.
Solution Approach 2:
The circuit transitions from a single-phase sequential charging approach to a multi-phase parallel charging approach. By adding the dimension of multiple clock phases and parallel pump unit cells, the system achieves faster voltage buildup without increasing individual capacitor sizes, effectively solving the area-time tradeoff through dimensional expansion of the charging architecture.
Data Source
AI summary
A charge pump circuit (300) includes a charge pump (330), and clocking circuitry that includes a clock generator (310) and a bypass circuit (320). The clocking circuitry generates clock signals and higher frequency alternative clock signals, for driving the charge pump. Upon start-up of the charge pump circuit and depending on a present value of an output voltage of the charge pump, the clocking circuitry couples to the charge pump either the alternative clock signals and not the clock signals, or the clock signals and not the alternative clock signals. Prior to completion of start-up of the charge pump circuit, at least two rows of pump unit cells are driven by a same alternative clock signal, thereby causing a pump unit cell in a row to charge/discharge at a same time as another pump unit cell in another row, thereby decreasing a start-up time of the charge pump circuit.