Envelope Detection Circuit for Sub-THz CFO and Phase Noise
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Solution Overview
Problem
High-frequency oscillators in sub-THz communication systems are prone to phase noise and Carrier Frequency Offset (CFO), leading to high symbol error rates, and existing solutions like envelope detection for coherent demodulation require high transmission power and complex signal processing.
Innovation Solution
An envelope detection circuit and method that transposes signals from a high-frequency band to an intermediate band without using a local oscillator, reducing phase noise impact and enabling coherent demodulation with improved spectral efficiency and energy efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high-frequency oscillators are used in sub-THz communication systems, then data transmission rate is improved, but phase noise and Carrier Frequency Offset increase leading to high symbol error rates
Solution Approach 1:
The patent extracts and eliminates the high-frequency oscillator from the receiver architecture, replacing it with an envelope detection circuit that operates at baseband. This removes the source of phase noise and CFO while preserving the ability to transmit high-rate data through the RF front-end, thereby improving reliability without sacrificing productivity.
Solution Approach 2:
The patent introduces an intermediary envelope detection circuit that mediates between the high-frequency RF signal and the baseband processing. This circuit detects the envelope of the received signal and reconstructs the modulated data without requiring a local oscillator, thus avoiding phase noise while maintaining data transmission capability.
2Productivity
If envelope detection is used for coherent demodulation, then spectral efficiency is improved, but transmission power requirement increases significantly
Solution Approach 1:
The patent applies partial action by detecting only the envelope of the received signal rather than performing full coherent demodulation. This partial detection approach achieves sufficient spectral efficiency for the application while avoiding the need for excessive transmission power that would be required for complete coherent demodulation with phase recovery.
3Reliability
If Hilbert transform is performed for envelope detection, then coherent demodulation is achieved, but device complexity increases
Solution Approach 1:
The patent replaces the complex Hilbert transform operation with a simpler envelope detection approach that uses basic rectification and filtering operations. This simpler 'disposable' method achieves coherent demodulation capability without requiring the complex computational resources of a Hilbert transform, thereby reducing device complexity while maintaining reliability.
Data Source
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AI summary
This envelope detection circuit comprises: - a first multiplier (40) capable of multiplying a first copy of a signal received on an input port (Pe34) by itself - a modifier (42) capable of modifying the amplitude of the power spectrum of a second copy of the signal received on the input port, at the frequency fc without modifying the amplitude of this power spectrum in a useful frequency band, - a second multiplier (44) capable of multiplying the modified signal by itself, - a subtractor (46) capable of subtracting the signals delivered by the multipliers, - a filter (50) capable of eliminating the frequency components greater than or equal to 2fc in a signal obtained from the signal delivered by the subtractor, this filter being capable of delivering the result of this filtering on an output connected to an output port of the envelope detection circuit.