Phase Domain Signal Demodulation Circuit for Wireless Transceivers
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Solution Overview
Problem
Conventional frequency offset estimation and demodulation/decoding operations in wireless data transmission require complex circuitry, significant power, and large chip space due to the need for complex multiplication and separate circuitry for each task, making them inefficient in terms of power usage and space.
Innovation Solution
A signal demodulation circuit and method that performs frequency offset estimation and demodulation/decoding using a single correlator element in the phase domain, employing autocorrelation and correlation with frequency compensation, which reduces circuit complexity and power consumption by using scalar subtraction operations instead of complex multiplication.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If complex multiplication is used for correlation and autocorrelation operations, then demodulation accuracy is maintained, but circuit complexity and power consumption increase significantly
Solution Approach 1:
The patent transforms the domain of operation from I/Q complex space to phase-only space by converting I/Q samples to phase values. This parameter change allows correlation and autocorrelation to be performed using simple scalar subtraction on phase values instead of complex multiplication, dramatically reducing circuit complexity while preserving demodulation accuracy through phase information.
Solution Approach 2:
The patent replaces the complex mathematical operation of complex multiplication with a simpler mechanical-like operation of scalar subtraction in the phase domain. This substitution eliminates the need for complex multipliers, adders, and associated control logic, resulting in a much simpler circuit implementation that achieves the same demodulation function.
2Reliability
If separate circuitry is used for frequency offset estimation and demodulation/decoding, then each function can be optimized independently, but total power consumption and chip area increase
Solution Approach 1:
The patent merges the frequency offset estimation function and the demodulation/decoding function into a single unified circuit that performs both operations. By using the same phase-domain correlator for both autocorrelation (frequency estimation) and correlation (demodulation), the patent eliminates redundant circuitry and reduces total power consumption while maintaining independent optimization of each function through software-controlled operation modes.
Solution Approach 2:
The patent creates a universal correlator circuit that can perform multiple functions: frequency offset estimation via autocorrelation and demodulation via correlation with PN code. This multi-functional approach allows a single circuit element to replace what would traditionally require separate dedicated circuits, reducing overall power consumption and chip area while maintaining the ability to optimize each function's performance.
3Measurement precision
If multiple autocorrelation values are generated for frequency offset estimation, then estimation accuracy improves, but calculation time and power consumption increase
Solution Approach 1:
The patent changes the operational parameters of autocorrelation by working in the phase domain rather than I/Q domain. This allows multiple autocorrelation values to be computed more efficiently using scalar subtraction, reducing the computational burden and calculation time while still generating multiple values for accurate frequency offset estimation through maximum detection.
Data Source
AI summary
Methods and receiver circuits are provided for correlating an incoming signal with PN codes. An embodiment of the method includes receiving I/Q baseband samples in the I/Q domain; converting the I/Q baseband samples to phase baseband samples; generating a pseudonoise (PN) code; converting the PN code to PN phase data; performing a correlation on the phase baseband samples using the PN phase data to generate correlated I/Q values; performing an adding operation on the correlated I/Q values to generate demodulated I/Q values; converting the demodulated I/Q values into demodulated phase values; performing a frequency correction operation on the demodulated phase values to generate frequency correction data; converting the demodulated I/Q values into demodulated magnitude values; and performing signal decoding and synchronization on the magnitude values to generate output data. The operation of performing correlation on the phase baseband samples using the PN phase data is accomplished using scalar subtraction.