Multi-Stage Harmonic I/Q Receiver for Low Phase Noise Conversion
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Solution Overview
Problem
Designing ultrahigh frequency I/Q transmitters/receivers is challenging due to difficulties in generating stable high-frequency oscillators and reducing phase noise, especially in integrated circuits, where direct conversion receivers fail to maintain stability and accuracy.
Innovation Solution
A multi-stage harmonic mixer system is employed to synchronize and convert signal frequencies, reducing oscillation frequency and phase noise, enabling efficient I/Q conversion and power consumption reduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If direct conversion receiver uses high frequency oscillator, then frequency conversion capability is improved, but phase noise deteriorates quickly
Solution Approach 1:
The frequency conversion process is divided into multiple stages: first converting RF to intermediate frequency, then converting intermediate frequency to baseband. This segmentation allows each oscillator to operate at lower, more stable frequencies rather than requiring a single high-frequency oscillator, thereby reducing phase noise while maintaining frequency conversion capability.
Solution Approach 2:
An intermediate frequency signal is introduced as a mediator between the RF input and baseband output. This intermediate frequency acts as a bridge, allowing the system to achieve high-frequency conversion capabilities through multiple lower-frequency conversion steps, thus improving phase noise performance while maintaining the ability to handle high-frequency signals.
2Speed
If super high frequency PLL is designed for generating high frequency, then frequency generation capability is improved, but design difficulty and complexity increase
Solution Approach 1:
The frequency generation process is segmented into multiple PLL stages, each operating at lower frequencies. The first PLL generates intermediate frequency from reference frequency, and the second PLL generates baseband from intermediate frequency. This segmentation reduces the complexity of designing super high frequency PLL while maintaining the capability to generate high-frequency signals.
Solution Approach 2:
Intermediate frequency serves as a mediator in the frequency generation process. Instead of directly generating super high frequency from reference frequency in a single PLL stage, the system uses intermediate frequency as a stepping stone, simplifying the design of each PLL stage while achieving the overall high-frequency generation capability.
3Ease of manufacture
If receiver uses harmonic mixer with Vlo frequency at half RFin frequency, then frequency generation becomes easier and phase noise is reduced, but 45° phase frequency generation becomes difficult
Solution Approach 1:
The phase generation process is segmented into multiple stages using multiple harmonic mixers. Instead of requiring a single complex 45° phase generator, the system uses multiple mixers with simpler phase requirements (0°, 90°, 180°, 270°), combining their outputs to achieve the desired 45° phase accuracy. This segmentation simplifies each individual stage while maintaining overall precision.
Solution Approach 2:
Multiple harmonic mixers with different phase outputs (0°, 45°, 90°, 135°, 180°, 225°, 270°, 315°) are combined to generate the complete set of phase frequencies. By merging the outputs of multiple mixers, the system achieves accurate 45° phase generation that would be difficult to obtain from a single mixer, thereby improving phase accuracy while maintaining ease of manufacture.
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 system effectively generates low-phase-noise local frequencies, simplifies the realization of I/Q MODEM, and reduces overall power consumption by lowering oscillation frequencies, facilitating accurate I/Q signal processing.
Implementation Method 1
a first harmonic mixer unit for receiving the first signal and the second signal, generating, based on the first signal and the second signal, a third signal having a frequency size converted to a second size
Data Source
AI summary
A receiver using a harmonic mixer includes a signal receiver for receiving a first signal, a frequency generator for synchronizing a phase of the received first signal, down-converting a frequency size of the synchronized first signal as much as a first size, and outputting the down-converted signal as a second signal; a first harmonic mixer unit for receiving the first signal and the second signal, generating a third signal having a frequency size down-converted as much as a second size, and outputting the third signal. The receiver further includes a second harmonic mixer unit for receiving the third signal and outputting an In-phase signal having a frequency size down-converted as much as a third size, and a third harmonic mixer unit for receiving the third signal and outputting a Quadrature-phase signal having a frequency size down-converted as much as a third size.