Bidirectional LO Injection for Multi-Band mmWave Image Rejection
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Solution Overview
Problem
Current mm-Wave communication systems face challenges in designing wideband transceiver frontends for multi-band 5G NR applications due to high power consumption and large chip area requirements for generating wideband local oscillator signals, especially across non-contiguous frequency bands like 24-43.5 GHz, which necessitate multiple power-hungry phase-locked loops.
Innovation Solution
A bidirectional signal-selection and image-rejection transceiver architecture that injects a local oscillator signal between two frequency bands, reducing the LO tuning range and power consumption by using a single multiplier and RF phased locked loop, enabling dual-polarization and bi-directional LO injection, and employing a dual-polarization N×N large-element active array with centralized PLL synchronization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple wideband power-hungry LO generation sets with several phase locked loops are used to generate wideband LO signals for multi-band mm-Wave communication, then the LO signal coverage and image rejection are improved, but the power consumption and chip area increase significantly
Solution Approach 1:
The patent implements bidirectional LO injection where a single LO signal is injected into both upper and lower sidebands of the mixer, enabling the same LO to serve multiple frequency bands (e.g., 24 GHz and 37 GHz bands) simultaneously. This multi-functional approach eliminates the need for separate LO generation sets for each band, reducing power consumption while maintaining wideband coverage
Solution Approach 2:
The patent merges multiple LO generation functions into a single phase-locked loop (PLL) system. By combining the LO signal generation for multiple bands into one unified PLL architecture with bidirectional injection, the system reduces the total number of PLLs required, thereby decreasing both power consumption and chip area while still supporting multi-band operation
2Adaptability or versatility
If multiple wideband power-hungry LO generation sets with several phase locked loops are used to generate wideband LO signals for multi-band mm-Wave communication, then the LO signal coverage and image rejection are improved, but the chip area increases significantly
Solution Approach 1:
The single PLL architecture performs multiple functions by generating LO signals that are bidirectionally injected into mixers to cover multiple frequency bands. This universal LO generation approach replaces multiple band-specific PLLs, significantly reducing the required chip area while maintaining adaptability across 24 GHz, 37 GHz, and other mm-Wave bands
Solution Approach 2:
The patent merges the functionality of multiple LO generation circuits into a single integrated PLL system with bidirectional injection capability. This consolidation reduces the total chip area occupied by LO generation components while preserving the ability to support multiple frequency bands through clever signal routing and mixing architecture
3Use of energy by stationary object
If bidirectional LO injection is implemented for multi-band operation, then the LO tuning range is reduced and power consumption decreases, but the image rejection complexity increases
Solution Approach 1:
The patent employs asymmetric I/Q signal routing where the in-phase and quadrature components are deliberately assigned different polarities for upper and lower sideband signals. This asymmetric configuration enables automatic image rejection through constructive and destructive interference patterns, simplifying the overall image rejection mechanism while maintaining bidirectional operation
Solution Approach 2:
The patent converts the potential harm of image signals into a beneficial feature by using controlled constructive and destructive interference. The asymmetric I/Q routing creates natural nulls at image frequencies through signal cancellation, transforming what would normally be harmful interference into a mechanism for automatic image rejection without requiring additional complex filtering
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
This approach reduces power consumption, phase noise, and chip area, while enabling efficient multi-band operation and image rejection, supporting future 5G and beyond MIMO/phased array communications with a lower mm-Wave LO signal generation requirement.
Implementation Method 1
a local oscillator (LO) signal is mixed with radio frequency (RF) signals to perform frequency conversion
Data Source
AI summary
An RF frontend integrated circuit (IC) device comprises one or more RF transceivers to transmit and receive RF signals within a first frequency band and a second frequency band that is higher than the first frequency band. The RF frontend IC device further comprises a bidirectional LO signal generation circuit coupled to the one or more transceivers to generate a bidirectional LO signal. The bidirectional LO signal is injected between the first frequency band and the second frequency band. The bidirectional LO signal generation circuit is to perform a high-side LO injection for the RF signals within the first frequency band by injecting the bidirectional LO signal having an LO frequency higher than the first frequency band and to perform a low-side LO injection for the RF signals within the second frequency band by injecting the bidirectional LO signal having the LO frequency lower than the second frequency band.