Coherent Receiver Signal Summation for ADC Reduction
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Solution Overview
Problem
Conventional optical signal receivers require four analog-to-digital converters (ADCs), leading to high power consumption, and experience signal loss due to polarization rotation during signal cancellation when orthogonal signals are added.
Innovation Solution
A coherent receiver method that separately quantizes and combines in-phase and quadrature signals, performing phase-inversion processing if the sum of signals is below a preset value to avoid signal loss, reducing the number of signals that need quantization and thus the number of ADCs required.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If four ADCs are used for quantizing all analog signals, then signal reception reliability is maintained, but power consumption increases
Solution Approach 1:
The patent segments the signal processing into two paths: a first path that sums analog signals before quantization (reducing ADC count) and a second path that quantizes signals separately (maintaining reliability). This segmentation allows the system to achieve low power consumption while preserving signal reception reliability through the redundant second path.
2Device complexity
If analog signals are summed before quantization, then the number of ADCs is reduced, but signal cancellation occurs when signals are orthogonal
Solution Approach 1:
The patent applies preliminary anti-action by detecting the orthogonality state of analog signals before summation and preemptively adjusting the phase of one signal to prevent cancellation. The phase adjustment circuit modifies the phase of the second analog signal based on the detected state, ensuring constructive interference rather than cancellation when signals are summed.
Solution Approach 2:
The patent implements feedback by using a detection circuit to monitor the orthogonality state of incoming analog signals and feeding this information back to a phase adjustment circuit. This closed-loop feedback mechanism continuously adapts the signal phase to prevent cancellation, ensuring reliable signal reception while maintaining the reduced ADC configuration.
3Reliability
If phase-inversion processing is applied to prevent signal loss, then signal reception is maintained, but processing complexity increases
Solution Approach 1:
The patent applies preliminary action by performing phase inversion processing on analog signals before they are summed, rather than after detection. This preliminary adjustment prevents signal cancellation from occurring in the first place, simplifying the overall processing by eliminating the need for complex post-processing correction algorithms.
Data Source
AI summary
An optical signal processing method and a coherent receiver, wherein an in-phase signal XI in a first polarization direction and an in-phase signal YI in a second polarization direction are added up to obtain a signal I; a quadrature signal XQ in the first polarization direction and a quadrature signal YQ in the second polarization direction are added up to obtain a signal Q; and quantization, combination, and digital signal processing are performed on the I and the Q. After summation, two signals need to be quantized. Therefore, a quantity of ADCs is reduced by half. In addition, because power consumption of a summation component is less than that of an ADS, power consumption of optical signal processing can be reduced. In addition, because there is a preset value, the summation may be performed after phase-inversion is performed on one analog signal, thereby avoiding a signal loss caused by the summation.