Differential Vector Modulator Attenuator for Phased Array Antennas
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Solution Overview
Problem
Current vector modulators in phased-array antennas face challenges in achieving accurate phase and amplitude control over a wide frequency range due to parasitic transmission phase variation, power consumption issues, and sensitivity to process-voltage-temperature (PVT) variations, as well as assembly/packaging problems with distributed step attenuators.
Innovation Solution
A distributed attenuator-based vector modulator architecture that uses a plurality of controllable varistors between transmission lines to attenuate differential signals, allowing for precise amplitude and phase control without the need for digital-analog converters (DACs), and incorporates a differential topology to reduce parasitic effects and enhance robustness against PVT variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If variable gain amplifiers (VGAs) are used in vector modulators to achieve broadband phase and amplitude variations, then phase and amplitude control over a wide frequency range is improved, but parasitic transmission phase variation increases leading to inaccurate control
Solution Approach 1:
The patent replaces the mechanical/analog VGA-based amplitude control system with a digital switching system using attenuators controlled by digital signals. This substitution eliminates the parasitic transmission phase variation inherent in analog VGAs while maintaining broadband phase and amplitude control capability through digital signal processing and switching networks.
Solution Approach 2:
The patent changes the control parameter from analog voltage/current control in VGAs to digital switching control in the attenuator system. By using digital control signals to switch between discrete attenuation levels, the system achieves accurate phase and amplitude control without the continuous variation parasitics that plague analog VGA-based systems.
2Reliability
If VGAs are used to increase robustness against interferers and jamming, then linearity and interference rejection are improved, but power consumption increases which is critical for modules with limited prime power
Solution Approach 1:
The patent changes the operating state of the attenuators based on signal conditions, switching between low-power digital control mode and high-linearity attenuation mode only when needed. This allows the system to maintain robustness against interferers when required while minimizing power consumption during normal operation.
Solution Approach 2:
The patent replaces the high-power-consuming analog VGA system with a digital switching-based attenuator system that achieves similar or superior interference rejection with significantly lower power consumption, as digital switching circuits consume far less power than continuous analog amplification.
3Ease of operation
If distributed step attenuators with single-ended topology are used to vary amplitudes, then amplitude control is achieved, but sensitivity to parasitic effects from assembly and packaging increases
Solution Approach 1:
The patent employs a differential topology where signal paths are arranged symmetrically with respect to a common reference, creating balanced signal flow that inherently rejects common-mode parasitic effects from bondwires and packaging. This asymmetric arrangement of differential pairs nullifies the impact of ground connections and external parasitics.
Solution Approach 2:
The patent replaces the single-ended topology with a differential topology system, where signals are transmitted as balanced differential pairs. This substitution fundamentally changes the electromagnetic field distribution and current paths, making the system immune to ground reference parasitics and bondwire effects that plague single-ended designs.
4Extent of automation
If VGAs are used with digital-analog converters (DACs) for digital control, then digital control capability is improved, but overall power consumption increases and PVT sensitivity adds inaccuracy
Solution Approach 1:
The patent replaces the DAC-based digital-to-analog control system with a direct digital switching control system. Digital control signals directly drive the switching elements of the attenuators without requiring analog conversion, eliminating the power consumption and PVT sensitivity of DACs while maintaining full digital control capability.
Solution Approach 2:
The patent extracts and removes the DAC component from the control chain, eliminating its power consumption and PVT-related inaccuracies. The digital control function is retained and performed directly by digital switching circuits that respond to digital control signals without intermediate analog conversion stages.
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 achieves low parasitic phase variation, high linearity, and robustness against PVT variations, enabling accurate phase and amplitude control over a wide bandwidth with reduced power consumption and improved assembly reliability, particularly suitable for silicon-based semiconductor technologies.
Implementation Method 1
One or more varistors are arranged between adjacent transmission lines along the first signal path and the second signal path to controllably connect the first signal path with the second signal path, thereby attenuating the differential signals
Data Source
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AI summary
An attenuator (500) comprises: a two-line input (In+, In-) and a two-line output (Out+, Out-) connected by a first signal path (11) and a second signal path (12) for enabling the attenuator (500, 501, ...) to attenuate differential signals; a first plurality of transmission lines (510, 512, ...) being arranged along the first signal path (11) and a second plurality of transmission lines (511, 513, ...) being arranged along the second signal path (12); and one or more varistors (520, 521) arranged between adjacent transmission lines (510, 512, 511, 513) along the first signal path (11) and the second signal path (12) to controllable connect the first signal path (11) with the second signal path (12), thereby attenuating the differential signals.