Gilbert Cell Mixer Phase Control for Radar Directional Characteristics
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Solution Overview
Problem
Monostatic multibeam radar sensor devices for motor vehicles face challenges in controlling the phase position of leakage signals in Gilbert cell mixers, leading to unpredictable directional diagrams and reduced isolation, which affects the accuracy of angle estimation and interference reduction.
Innovation Solution
The use of separate power sources to selectively control the current amplification of switching transistor pairs in the Gilbert cell mixer allows for switchable phase positioning of the overcoupling signal between 0° and 180°, enabling controlled leakage signal phase management and improving the directional characteristic of the radar sensor device.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a Gilbert cell mixer is used in the isolating mixer for receiving channels, then the directional characteristic can be formed, but the non-ideal isolation between the local oscillator signal input and the receiving channel causes unpredictable leakage signals and reduced isolation performance
Solution Approach 1:
The patent applies dynamics by making the leakage signal controllable through a control signal that switches between two states. The leakage signal, which was previously unpredictable, is now dynamically adjusted by controlling the phase position of the overcoupling signal, allowing the system to adapt between different operational states (narrow and wide transmission sum patterns).
Solution Approach 2:
The patent changes the phase parameter of the overcoupling signal to control the leakage signal. By switching the phase position between specific values (0° and 180°), the system modifies the isolation characteristics and directional diagram, transforming a static isolation limitation into a controllable parameter.
2Adaptability or versatility
If the phase position of the overcoupling signal is controlled to manage leakage signals, then the directional characteristic becomes switchable, but the device complexity increases due to additional control mechanisms
Solution Approach 1:
The control signal serves multiple functions: it controls the phase position of the overcoupling signal, manages the leakage signal, and switches between different transmission sum patterns (narrow and wide). This multi-functionality reduces the need for separate control mechanisms for each function, thereby limiting the increase in device complexity.
3Measurement precision
If separate power sources are used to control the current amplification of switching transistor pairs, then the phase position of the overcoupling signal can be precisely controlled, but the device complexity and power consumption increase
Solution Approach 1:
The patent segments the power supply by providing separate power sources for the two switching transistor pairs (first and second switching transistor pairs). This segmentation allows independent control of each pair's current amplification, enabling precise phase position control of the overcoupling signal. The segmentation is targeted and minimal, affecting only the critical mixing components rather than the entire system.
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 allows for a switchable transmission sum pattern, enhancing the angle estimation range and reducing interference, particularly within the 4° to 8° angular range, by effectively managing the phase position of the outer radar beam lobes, thereby improving the overall performance of the radar sensor system.
Implementation Method 1
emits a transmission power via this receiving channel, using an overcoupling signal
Implementation Method 2
mix the signal received by the antenna with a portion of the signal supplied via the RF source port. The mixed product is then an intermediate frequency signal whose frequency indicates the frequency difference
Implementation Method 3
The mixed product is then an intermediate frequency signal whose frequency indicates the frequency difference between the transmitted and received signals. This intermediate frequency signal provides information about the Doppler shift occurring at the radar target upon reflection of the transmitted signal, and thus information about the relative velocity
Data Source
AI summary
A monostatic multibeam radar sensor device for a motor vehicle, including a directional characteristic of an antenna unit having at least one transceiving channel and at least one receiving channel, and including a mixer system, which has an at least approximately isolating mixer for at least one of the receiving channels. The at least approximately isolating mixer includes a Gilbert cell mixer, which, due to a non-ideal isolation between an input of the local oscillator signal and the corresponding receiving channel, emits a transmission power via this receiving channel, using an overcoupling signal, the transmission power influencing the directional characteristic of the antenna unit and the directional characteristic being switchable by controlling the phase position of the overcoupling signal.