Phase-Multiplexed Quadrature Receiver with Single-Mixer Demodulation
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Solution Overview
Problem
Conventional quadrature receivers suffer from I/Q imbalance, LO feedthrough, DC offset, gain/amplitude mismatch, and high power consumption due to dual I/Q mixers and separate signal paths, which degrade their ability to demodulate digital signals, especially in wideband systems.
Innovation Solution
A phase-multiplexed quadrature receiver employs a single I/Q mixer and a low-resolution phase shifter that rapidly switches between discrete phase states to demodulate complex radio-frequency waveforms, using synchronized baseband switches to sample voltages across capacitors, eliminating the need for dual paths and reducing power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If dual I/Q mixers and separate signal paths are used, then demodulation capability is provided, but power consumption increases and I/Q imbalance occurs
Solution Approach 1:
The patent merges the function of dual I/Q mixers into a single mixer by multiplexing four phase states (0°, 90°, 180°, 270°) of the local oscillator signal through a phase shifter. This single mixer processes both I and Q components sequentially within each symbol period, eliminating the need for separate dual mixer paths and reducing power consumption while maintaining demodulation capability.
Solution Approach 2:
The invention employs periodic phase switching of the local oscillator signal through a phase shifter that cycles through four discrete phase states within each symbol period. This periodic action allows a single mixer to perform the work of two mixers by processing I and Q components in alternating time slots, thereby reducing power consumption while preserving full quadrature demodulation functionality.
2Reliability
If dual I/Q mixers and separate signal paths are used, then demodulation capability is provided, but I/Q imbalance and LO feedthrough occur
Solution Approach 1:
By combining I and Q processing into a single mixer with multiplexed phase states, the patent eliminates the separate signal paths that cause I/Q imbalance and LO feedthrough in conventional receivers. The single path architecture ensures consistent signal processing characteristics while the phase shifter maintains precise quadrature relationships.
3Reliability
If dual I/Q mixers and separate signal paths are used, then demodulation capability is provided, but device area increases
Solution Approach 1:
The patent consolidates the receiver architecture by merging dual I/Q mixers and separate signal paths into a single mixer with phase-multiplexed local oscillator input. This integration dramatically reduces the required device area while maintaining full quadrature demodulation capability through time-division processing of I and Q components.
4Use of energy by moving object
If single I/Q mixer with phase multiplexing is used, then power consumption is reduced, but signal processing complexity increases
Solution Approach 1:
The patent uses periodic phase switching of the local oscillator through a phase shifter that cycles through four discrete phase states within each symbol period. This structured periodic action simplifies the overall system by using a single mixer while the phase shifter handles the complexity of generating the required phase states, making the signal processing manageable through regular timing patterns.
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 solution reduces power consumption, eliminates I/Q imbalance, and provides inherent filtering, while maintaining demodulation performance, thus improving receiver efficiency and reducing area requirements.
Implementation Method 1
a mixer that receives the RF signal and a local oscillator signal and that transforms the complex radio-frequency waveform into a baseband voltage signal
Data Source
AI summary
A phase-multiplexed quadrature receiver includes an RF signal interface providing an RF signal to a mixer. The receiver includes a local oscillator and a phase shifter that multiplexes phase states of the local oscillator applied to the mixer between at least four I/Q phases within each symbol period of the RF signal to produce a complex radio-frequency waveform. A synchronized set of baseband switches that sample voltage from the mixer across at least two capacitors to demodulate the complex radio-frequency waveform into in-phase and quadrature components.