N-Path Single-Ended to Differential Conversion for Noise-Resistant ICs
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Solution Overview
Problem
Conventional single-ended to differential signal converters are bulky and lossy, making them inefficient for use in integrated circuits and prone to noise susceptibility, which can reduce the performance of communication devices.
Innovation Solution
The implementation of an N-path filter with switched capacitors to convert single-ended signals into differential signals by providing a 180-degree phase-shifted version of the input signal, forming a differential output signal, which is more area-efficient and less susceptible to noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional transformer-based conversion methods are used to convert single-ended signals to differential signals, then noise resistance is improved, but device area increases and signal loss occurs
Solution Approach 1:
The patent changes the fundamental operating parameters of the converter by using switched-capacitor circuits with controlled switching frequencies and duty cycles to generate the 180-degree phase-shifted signal, replacing the transformer-based electromagnetic coupling approach. This parameter change enables differential signal generation with reduced area and improved linearity.
Solution Approach 2:
The patent substitutes the electromagnetic field-based transformer mechanism with an electronic switching mechanism using capacitors and switches. This replacement eliminates the need for magnetic core and windings, significantly reducing the converter area while maintaining the phase-shifting function through electronic control.
2Reliability
If conventional transformer-based conversion methods are used to convert single-ended signals to differential signals, then noise resistance is improved, but signal loss increases
Solution Approach 1:
The patent replaces the lossy electromagnetic coupling in transformers with ideal capacitor charging and discharging cycles controlled by switches. The switched-capacitor approach minimizes resistive losses and magnetic core losses, reducing signal loss while maintaining noise resistance through differential signaling.
Solution Approach 2:
The patent employs periodic switching of capacitors at controlled frequencies to transfer and phase-shift the signal. This periodic action enables precise control of signal timing and amplitude, reducing distortion and energy loss compared to continuous electromagnetic coupling in transformers.
3Device complexity
If single-ended analog signals are used, then design constraints are simplified, but noise susceptibility increases
Solution Approach 1:
The patent introduces dynamic switching control to generate the complementary differential signal from a static single-ended input. The controlled switching action creates time-varying capacitor voltages that produce the 180-degree phase-shifted signal, dynamically converting single-ended to differential form to achieve noise immunity.
Solution Approach 2:
The patent segments the signal path into separate capacitor branches that independently process the single-ended signal to generate differential outputs. This segmentation allows independent optimization of each signal path while maintaining overall system simplicity, achieving noise resistance without excessive complexity.
Data Source
AI summary
This disclosure provides systems and apparatuses for converting a single-ended analog signal into a differential analog signal. In some implementations, a single-ended to differential signal converter may include an N-path filter to generate a 180 degree phase-shifted version of a single-ended input signal. The single-ended input signal and the 180 degree phase-shifted version of the single-ended input signal together may form a differential signal. In some implementations, the N-path filter may delay the single-ended input through a series of switched capacitors.