Charge Pump Efficiency Determination Using Current Limiter
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Solution Overview
Problem
The efficiency of charge pumps in semiconductor devices varies due to fabrication process variations, leading to inconsistent performance, where higher-efficiency pumps are compromised to meet the lowest efficiency requirements, resulting in suboptimal performance and increased current consumption.
Innovation Solution
A method to determine the efficiency of charge pumps by measuring the reference and comparison number of clock pulses with and without a current limiter, adjusting the current limiter gain to match the reference, and setting optimal control parameters such as ramp-up rate and clock frequency based on efficiency metrics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If charge pump design is optimized for lowest efficiency to meet all requirements, then reliability is improved, but productivity deteriorates
Solution Approach 1:
The patent implements dynamic adjustment of control parameters (ramp-up rate, clock frequency) based on measured efficiency characteristics. Each charge pump's parameters are individually optimized rather than using a static conservative design, allowing the system to adapt to actual device performance and achieve both reliability and productivity goals.
Solution Approach 2:
The invention changes operational parameters (clock frequency, ramp-up rate) based on measured efficiency metrics. By measuring actual efficiency and adjusting parameters accordingly, the system moves from a fixed conservative design to a variable optimized design, resolving the contradiction between meeting minimum requirements and maximizing performance.
2Use of energy by moving object
If charge pump efficiency is increased, then use of energy is improved, but manufacturing precision deteriorates
Solution Approach 1:
The patent implements self-characterization where each charge pump measures its own efficiency and determines its own optimal parameters. This self-service approach compensates for manufacturing variations without requiring external calibration or rejection of out-of-spec devices, allowing high efficiency while accepting normal manufacturing variability.
Solution Approach 2:
The invention uses feedback from efficiency measurements to adjust control parameters. By measuring actual efficiency and using that information to optimize operation, the system compensates for manufacturing variations and achieves consistent performance across devices with different efficiency characteristics.
3Measurement precision
If measurement precision is increased to accurately determine efficiency, then reliability is improved, but device complexity increases
Solution Approach 1:
The patent uses an intermediary current limiter circuit that simplifies efficiency measurement. By placing a controllable current limiter in series with the charge pump input, the system can measure efficiency through clock pulse counting without requiring complex direct power measurement circuitry, thus achieving accurate measurement with minimal added complexity.
Data Source
AI summary
Techniques and apparatuses are provided for determining the efficiency of a charge pump. A charge pump is driven during a measurement period without limiting its input current. The driving can include ramping up the output of the charge pump from an initial level to a final level and maintaining the output at the final level. A counter counts a number of clock pulses provided to the charge pump during the measurement period. Using a current mirror which limits the input current, a ratio of the current mirror is determined which results in a similar number of clock pulses during the measurement period. The ratio indicates an efficiency of the charge pump and can be used to set control parameters such as ramp up rate and clock frequency.