Antenna-Switched Radar Receiver With LNA Paths for RF Isolation
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Solution Overview
Problem
Existing antenna switching systems face challenges such as high RF front-end loss, poor isolation among antennas, and increased power consumption when using a single shared receiver channel for multiple antennas.
Innovation Solution
The proposed antenna switching system includes individual antenna sub-circuits with differential low-noise amplifiers and shunt transistor switches, coupled to a shared receiver sub-circuit that can mix and convert signals from either antenna sub-circuit based on the state of the transistors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If a single shared receiver channel is used for multiple antennas, then silicon area and cost are reduced, but RF front-end loss increases and antenna isolation deteriorates
Solution Approach 1:
The receiver system is segmented into multiple independent antenna sub-circuits, each with its own LNA and switching mechanism, rather than using a single shared receiver channel. This segmentation allows each antenna path to be independently optimized while still sharing common components like the mixer and ADC, thereby reducing RF loss while maintaining area efficiency.
Solution Approach 2:
Dynamic switching mechanisms are implemented in each antenna sub-circuit, allowing the system to selectively activate only the required antenna path at any given time. This dynamic control optimizes RF performance by ensuring active antenna paths have dedicated amplification resources while maintaining the area benefits of sharing common receiver components.
2Area of stationary object
If a single shared receiver channel is used for multiple antennas, then silicon area and cost are reduced, but antenna isolation deteriorates
Solution Approach 1:
The receiver is segmented into multiple antenna sub-circuits with independent LNAs and switching elements. Each sub-circuit can be independently controlled and isolated, preventing signal leakage between antenna channels while still sharing common downstream components like the mixer and ADC, thus maintaining both isolation and area efficiency.
Solution Approach 2:
Switching elements are introduced as intermediary components between each antenna and its dedicated LNA. These switches act as isolation barriers that can completely disconnect inactive antenna paths from the receiver chain, ensuring excellent antenna isolation while allowing the system to share common receiver components for area efficiency.
3Area of stationary object
If switching elements are used to utilize multiple antennas per single receiver channel, then silicon area is reduced, but power consumption increases
Solution Approach 1:
Multiple antenna sub-circuits are merged to share common receiver components such as the mixer, local oscillator, and ADC. This combining approach reduces the total component count and power consumption compared to fully independent receiver channels, while still providing dedicated amplification paths for each antenna through the antenna sub-circuits.
Solution Approach 2:
The common receiver components (mixer, ADC) serve multiple antenna sub-circuits simultaneously, making them multi-functional. This universality allows the system to process signals from multiple antennas through shared resources, reducing overall power consumption while maintaining the ability to independently process each antenna's signal through dedicated sub-circuits.
4Reliability
If switches are placed following the mixers, then RF front-end noise performance and isolation improve, but power consumption and silicon area increase
Solution Approach 1:
Switching elements are placed before the LNAs in each antenna sub-circuit, performing the antenna selection action early in the signal chain. This preliminary switching allows the system to activate only the required LNA and subsequent receiver components, reducing power consumption while maintaining noise performance by ensuring the active path has dedicated amplification resources.
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 reduces power consumption, increases antenna-channel isolation, and improves gain and band matching, while minimizing design area requirements and maintaining effective signal processing.
Implementation Method 1
Each antenna sub-circuit includes a balun, a transistor, and a low-noise amplifier
Implementation Method 2
a switching mechanism can be included in each of the antenna sub-circuits prior to a low-noise amplifier, such that the receiver sub-circuit only receives a signal from one of the antenna sub-circuits
Implementation Method 3
Each antenna sub-circuit includes a balun, a transistor, and a low-noise amplifier
Implementation Method 4
The receiver sub-circuit includes a transformer having a first set of terminals coupled to the first and second low-noise amplifiers and a second set of terminals coupled to a mixer
Data Source
AI summary
Embodiments disclosed herein relate to antenna switching in radar applications. In an example, a system including a first antenna sub-circuit, a second antenna sub-circuit, and a receiver sub-circuit is provided. The first antenna sub-circuit is configured to couple to a first antenna and includes a first balun, a first transistor, and a first low-noise amplifier. The second antenna sub-circuit is configured to couple to a second antenna and includes a second balun, a second transistor, and a second low-noise amplifier. The receiver sub-circuit includes a transformer having a first set of terminals coupled to the first and second low-noise amplifiers and a second set of terminals coupled to a mixer, the mixer, a first amplifier, a second amplifier, and an analog-to-digital converter. The receiver sub-circuit is configured to receive a signal from either the first or second antenna sub-circuit based on a state of the first and second transistors.