Transformer-Based IQ Generator for Millimeter-Wave Image Rejection
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Solution Overview
Problem
Next-generation 5G communication devices require a higher data rate and broader bandwidth, particularly at millimeter-wave frequencies, but existing low-IF receiver architectures face performance degradation due to lossy wideband in-phase quadrature (IQ) local oscillator generation, necessitating an on-chip receiver with wideband image rejection.
Innovation Solution
A multi-band image-reject receiver design incorporating a transformer-based IQ generator circuit, load resistors, and downconverters with mixers to generate differential in-phase and quadrature local oscillator signals, coupled with low-noise amplifiers and poly-phase filters to process RF signals into intermediate frequency signals effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a low-IF receiver architecture is used to avoid flicker noise and dc offset, then receiver performance is improved, but mm-wave wideband IQ local oscillator generation becomes very lossy degrading mixer performance
Solution Approach 1:
The receiver is divided into multiple independent frequency bands (e.g., 24 GHz, 28 GHz, 37 GHz, 39 GHz bands), with each band having its own dedicated LO generation and mixing path. This segmentation allows optimization of each band independently, reducing overall loss by avoiding the need for a single wideband LO generator that suffers from high losses.
Solution Approach 2:
Each frequency band is equipped with band-specific local oscillators and mixing components optimized for that particular frequency range. This local quality approach ensures that each mixer receives an LO signal optimized for its specific operating frequency, minimizing conversion losses that would occur with a generic wideband LO approach.
2Productivity
If mm-wave frequency operation is implemented to support higher data rates, then data rate capability is improved, but image rejection becomes more difficult to achieve
Solution Approach 1:
The receiver architecture segments different frequency bands into separate processing paths, each with its own image rejection filtering optimized for that band's specific characteristics. This allows precise image rejection for each band without compromising the high data rate capability of mm-wave operation.
Solution Approach 2:
Poly-phase filters are introduced as intermediary components between the mixers and the baseband processing stage. These filters specifically target and eliminate image frequencies while preserving the desired signal, enabling effective image rejection in the mm-wave frequency range where direct conversion methods struggle.
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 solution enhances the performance of 5G communication devices by providing wideband image rejection and improved conversion gain, addressing the challenges of millimeter-wave frequency operation and enabling efficient data processing for applications like augmented reality and MIMO.
Implementation Method 1
a transformer-based IQ generator circuit, load resistors, and downconverters with mixers to generate differential in-phase and quadrature local oscillator signals
Data Source
AI summary
An RF receiver includes a low-noise amplifier (LNA) to receive and amplify RF signals, a transformer-based IQ generator circuit, one or more load resisters, one or more mixer circuit, and a downconverter. The transformer-based IQ generator is to generate a differential in-phase local oscillator (LOI) signal and a differential quadrature (LOQ) signal based on a local oscillator (LO) signal received from an LO. The load resisters are coupled to an output of the transformer-based IQ generator. Each of the load resisters is to couple one of the differential LOI and LOQ signals to a predetermined bias voltage. The mixers are coupled to the LNA and the transformer-based IQ generator to receive and mix the RF signals amplified by the LNA with the differential LOI and LOQ signals to generate an in-phase RF (RFI) signal and a quadrature RF (RFQ) signal. The downconverter is to down convert the RFI signal and the RFQ signal into IF signals.