Five-Stage CMOS Rectifier for Low-Leakage RF Energy Harvesting
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Solution Overview
Problem
Conventional CMOS rectifiers for RF energy harvesting face challenges such as high reverse leakage current, complex circuitry, and limited power conversion efficiency across a wide range of input power levels, making them unsuitable for efficient energy harvesting at both low and high input power levels.
Innovation Solution
A CMOS rectifier design incorporating an adaptive body biasing technique and a cross-coupled architecture, which adjusts transistor threshold voltage based on operational states to minimize reverse leakage current and enhance power conversion efficiency, utilizing multiple stages and body biasing capacitors to optimize performance across varying input powers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If Schottky diodes are used in rectifier circuits, then reverse leakage current is reduced, but fabrication cost increases due to extra masks and device integration complexity
Solution Approach 1:
The patent extracts the diode function from separate Schottky diode components and integrates it directly into the CMOS transistor structure by modifying the transistor layout and doping profiles, thereby eliminating the need for extra masks while maintaining low reverse leakage current performance
Solution Approach 2:
The patent merges the diode functionality with the CMOS transistor structure, combining what were previously separate components (Schottky diode and CMOS transistor) into a unified structure where the transistor serves both switching and rectification functions
2Ease of operation
If CMOS transistors with low or zero threshold voltage are used, then ease of operation improves, but reverse leakage current increases significantly
Solution Approach 1:
The patent implements dynamic threshold voltage control through body biasing, where the threshold voltage is adjusted in real-time based on the operational state of the transistor, allowing low threshold voltage during active operation for ease of switching while maintaining higher effective threshold voltage during standby to reduce leakage
Solution Approach 2:
The patent changes the electrical parameters of the CMOS transistor by applying body bias voltages that dynamically adjust the threshold voltage, enabling the transistor to operate with low threshold voltage when needed while suppressing reverse leakage current through parameter modulation
3Device complexity
If conventional rectifier designs are used, then device complexity is reduced, but power conversion efficiency is limited across wide input power ranges
Solution Approach 1:
The patent segments the rectifier into multiple stages with progressively higher voltage multiplication, where each stage handles a specific voltage range, allowing the overall system to maintain high efficiency across wide input power ranges while keeping individual stage complexity manageable
Solution Approach 2:
The patent extends the conventional single-stage rectifier design into a multi-dimensional voltage multiplication architecture, adding voltage multiplication capability as an additional dimension to the basic rectification function, thereby achieving high efficiency across wide power ranges
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 proposed CMOS rectifier achieves a peak power conversion efficiency of 78.2% at an input power of −27.5 dBm and a 100 kΩ load, outperforming conventional designs by maintaining high efficiency across a broader range of input power levels.
Implementation Method 1
an energy harvesting antenna configured to receive an electromagnetic radiation and generate an oscillating current
Data Source
AI summary
A circuit and methods describing a complementary metal-oxide semiconductor (CMOS) rectifier for use in radio frequency (RF) energy harvesting with body biasing by the RF input to control the threshold voltage of each transistor. The CMOS rectifier includes an energy harvesting antenna, and multiple rectifier stages. The antenna receives electromagnetic radiation from the environment and generates a DC current. The oscillating input current is an RF+ positive current during a first half cycle and is an RF− negative current during a second half cycle. A first rectifier stage includes a first capacitor connected to the RF+ positive current, a second capacitor connected to the RF− negative current and a cross coupled CMOS circuit connected to the antenna.