Charge-Domain Wakeup Receiver With Switched-Capacitor Interference Rejection
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Solution Overview
Problem
Current ultra-low power (ULP) receivers in wireless sensor networks face challenges such as low sensitivity, poor robustness against interference, and vulnerability to process, voltage, and temperature variations, as well as security issues like replay and energy attacks, hindering widespread adoption.
Innovation Solution
A wakeup receiver (WRX) with a charge-domain analog front end, incorporating a parallel RF rectifier, charge-transfer summation amplifier, and successive approximation ADC, which operates in discrete-time, eliminating the need for static bias currents and providing robustness against interference and PVT variations, while supporting secure wakeups and energy-efficient operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If continuous-time analog circuitry is used in ULP receive frontends, then power consumption is reduced, but sensitivity and robustness in the presence of interference deteriorate
Solution Approach 1:
The patent transitions from continuous-time analog processing to discrete-time processing, fundamentally changing the operational parameters of the receive frontend. This parameter change enables the system to achieve both low power consumption and high robustness by using switched-capacitor circuits that operate in discrete time steps, eliminating the trade-off between power savings and performance reliability
Solution Approach 2:
The patent replaces continuous-time analog circuitry with discrete-time switched-capacitor circuits. This substitution involves replacing the continuous signal processing mechanism with a discrete sampling and processing approach, where capacitors are switched in and out of circuit in discrete time steps, achieving both low power consumption and high robustness simultaneously
2Reliability
If IF frontend with continuous-time mixer and amplifiers is used, then sensitivity and selectivity are improved, but power consumption increases
Solution Approach 1:
The patent replaces the continuous-time mixer and amplifiers with discrete-time switched-capacitor circuits. The switched-capacitor implementation performs mixing and amplification functions in discrete time steps, eliminating the need for continuous-power-consuming analog mixers and amplifiers while maintaining high sensitivity and selectivity
Solution Approach 2:
The patent employs periodic switching of capacitors in discrete time steps to achieve signal processing functions. The switched-capacitor circuits operate in periodic cycles where capacitors are charged and discharged in discrete time intervals, replacing the continuous operation of traditional mixers and amplifiers with a periodic discrete-time approach that consumes significantly less power
3Use of energy by moving object
If ULP receivers are deployed in IoT networks, then active and average power are reduced, but selectivity and rejection of random pulsed interferers deteriorate
Solution Approach 1:
The patent replaces continuous-time analog filtering with discrete-time switched-capacitor filtering. The discrete-time implementation provides superior stopband rejection and selectivity by using precise capacitor switching sequences that create deep nulls in the frequency response, effectively rejecting random pulsed interferers while maintaining low power consumption
Solution Approach 2:
The patent changes the fundamental parameter of signal processing from continuous-time to discrete-time operation. This parameter change enables the use of switched-capacitor circuits that can achieve high selectivity and interferer rejection by manipulating capacitor switching timing and sequences, providing robustness against pulsed interferers while maintaining ULP power consumption
4Adaptability or versatility
If ULP receivers operate across wide temperature range, then adaptability is improved, but robustness to PVT variations deteriorates
Solution Approach 1:
The patent replaces continuous-time analog processing with discrete-time switched-capacitor processing. The discrete-time approach eliminates the PVT sensitivity inherent in continuous-time analog circuits, as the switched-capacitor operation depends on precise timing and capacitor ratios rather than continuous voltage or current levels, providing robustness across wide temperature ranges and process variations
Solution Approach 2:
The patent employs dynamic switching of capacitors in discrete time steps to achieve signal processing functions. The switched-capacitor circuits dynamically reconfigure their topology based on processing requirements, providing adaptability across different operating conditions including wide temperature ranges while maintaining robustness through the discrete-time nature of the operation
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 WRX achieves high sensitivity, robust interference rejection, and secure operation with low power consumption, maintaining performance across varying conditions, enabling reliable and rapid wakeups in industrial IoT environments.
Implementation Method 1
a parallel RF rectifier, charge-transfer summation amplifier, and successive approximation ADC
Implementation Method 2
charge-transfer summation amplifier
Data Source
AI summary
Embodiments of the invention include a wakeup receiver (WRX) featuring a charge-domain analog front end (AFE) with parallel radio frequency (RF) rectifier, charge-transfer summation amplifier (CTSA), and successive approximation analog-to-digital converter (SAR ADC) stages. The WRX operates at very low power and exhibits above-average sensitivity, random pulsed interferer rejections, and yield over process.