Negative Photodiode Charge Pump IC for Monolithic Light Harvesting
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Solution Overview
Problem
Existing light energy harvesting integrated circuits face limitations in output voltage and efficiency due to low photodiode output voltage and area requirements, necessitating complex and expensive post-processing or external components, which are not monolithic and increase system volume.
Innovation Solution
A light energy harvesting integrated circuit with a negative photodiode as the main harvester, a power management stage comprising an Interleaved Inverting Charge Pump and a Cross-Coupled Charge Pump, and a self-powered clock generator, all manufactured in a standard CMOS process, to invert and boost the voltage efficiently.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a negative photodiode is used as the main energy harvester, then voltage output and efficiency are improved, but the circuit complexity increases due to the need for voltage inversion and boosting stages
Solution Approach 1:
The patent combines the voltage inversion function and voltage boosting function into a single integrated charge pump circuit that processes the negative photodiode output. This merging of functions reduces the number of separate components and simplifies the overall circuit architecture while maintaining the ability to generate positive output voltage from the negative photodiode.
Solution Approach 2:
The charge pump circuit is designed to automatically invert and boost the voltage from the negative photodiode without requiring external control circuits or additional power sources. The circuit self-regulates the voltage conversion process, reducing the need for complex external control mechanisms.
2Volume of moving object
If monolithic integration is used for all components, then system size is reduced, but manufacturing complexity increases
Solution Approach 1:
The patent designs the integrated circuit to perform multiple functions using the same manufacturing process: photodiode fabrication, voltage inversion, and voltage boosting are all achieved within the standard CMOS process framework. This multi-functionality approach allows diverse circuit elements to be manufactured together without requiring specialized post-processing steps.
Solution Approach 2:
The patent utilizes standard CMOS process parameters and device structures to achieve monolithic integration. By working within the established parameter ranges of standard CMOS technology, the design achieves full integration without requiring exotic materials or complex manufacturing steps that would increase production difficulty.
3Ease of manufacture
If standard CMOS process is used for fabrication, then manufacturing cost and complexity are reduced, but output voltage is limited by photodiode characteristics
Solution Approach 1:
The charge pump circuit employs periodic switching action to progressively build up the output voltage from the photodiode's limited initial voltage. By repeatedly charging and discharging capacitive elements in sync with the photodiode's periodic operation, the circuit accumulates voltage over multiple cycles, achieving high output voltage despite the photodiode's low instantaneous voltage output.
Solution Approach 2:
The patent replaces direct voltage amplification (which would require complex analog circuits) with a charge pumping mechanism that transfers and accumulates electrical charge in discrete steps. This substitution of the voltage generation mechanism allows standard CMOS components to achieve high output voltages through iterative charge accumulation rather than direct amplification.
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 achieves higher voltage output and improved efficiency by integrating monolithic components, reducing the need for external components and minimizing system size, while maintaining efficient energy harvesting.
Implementation Method 1
When this region is illuminated, photons of sufficient energy strike the junction, creating electron-hole pairs that move in opposite directions, creating a current across the device with the so called photoelectric effect.
Implementation Method 2
The power management stage comprises a first charge pump to invert the generated negative voltage into a positive voltage; a second charge pump to boost the positive voltage a given pumping factor
Data Source
Figure 1~2
Figure 3~4
Figure 5
AI summary
A light energy harvesting integrated circuit is proposed. It comprises a main energy harvester including a negative photodiode (1) to harvest light energy from incident light and to generate a negative voltage (5) as a result; and a power management stage including: a first charge pump (2) to invert the generated negative voltage (5) into a positive voltage; a second charge pump (3) to boost the positive voltage a given pumping factor at an output of the light energy harvesting integrated circuit; and a clock generator (6) to generate complementarily clock driving signals (ϕ1, ϕ2) to drive the first and second charge pumps (2, 3), the second charge pump (3) being further driven using clock drivers (9).