Electrically Adjustable Phase Shifter for Radar Signal Isolation
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Solution Overview
Problem
Mono-static radar systems operating at high frequencies, such as 77 GHz, face significant interference issues due to poor signal isolation between transmitter and receiver circuits, leading to degraded system performance and the need for high supply voltages and current densities in active mixers, which are not supported by existing Gilbert-cell mixers.
Innovation Solution
An electrically adjustable phase shifter is implemented by adapting the effective length of a transmission line using amplifier stages to adjust the phase of signals, allowing for phase compensation in high-frequency communication units, particularly in mono-static radar systems, to reduce interference and improve signal-to-noise ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If high-end circulators or rat-race couplers are used to provide isolation between transmit and receive paths, then signal isolation is improved, but device complexity and cost increase
Solution Approach 1:
The patent introduces an electrically adjustable phase shifter as an intermediary component between the transmit and receive paths. This phase shifter uses controllable phase shifting elements (such as varactor diodes or switched transmission line segments) to provide adjustable phase delay, thereby achieving signal isolation without requiring complex circulators or rat-race couplers. The intermediary phase shifter simplifies the overall device complexity while maintaining effective isolation performance.
2Object-affected harmful factors
If ultra short transmit pulses are used to isolate transmitter signal from antenna, then transmitter isolation is improved, but transmission time is reduced
Solution Approach 1:
The patent implements preliminary action by using the electrically adjustable phase shifter to pre-adjust the phase of signals before they reach the antenna or receiver. By controlling the phase shift in advance, the system can achieve better signal isolation during the transmission pulse without requiring the pulse itself to be ultra-short. This allows for longer transmission times while maintaining isolation performance through the phase adjustment mechanism.
3Object-affected harmful factors
If spatially-separated antennas are used to provide high isolation between transmit and receive operations, then signal isolation is improved, but device complexity and space requirements increase
Solution Approach 1:
The patent merges the transmit and receive antenna elements into a single integrated structure, eliminating the need for spatially-separated antennas. By using the electrically adjustable phase shifter to provide signal isolation in the electrical domain rather than physical separation, the system achieves high isolation performance while maintaining a compact, integrated antenna design. This merging approach reduces device complexity and space requirements while maintaining isolation effectiveness.
4Reliability
If high supply voltages and current densities are applied to mixers to achieve linear operation, then mixer linearity is improved, but power consumption increases
Solution Approach 1:
The patent implements feedback by using the electrically adjustable phase shifter to dynamically adjust signal phases based on feedback from the received signal characteristics. This feedback mechanism allows the system to compensate for phase variations and maintain optimal mixer operation without requiring excessive supply voltages or current densities. The feedback-controlled phase adjustment enables linear mixer operation at lower power levels by optimizing the signal processing path.
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 effectively reduces phase shift differentials and improves noise performance, allowing for lower power consumption and enhanced signal-to-noise ratio, while enabling the use of more linear mixer cores without compromising output power.
Implementation Method 1
adjusting a phase of a high frequency signal by electrically changing an effective length of a transmission line
Implementation Method 2
electrically changing an effective length of a transmission line by electrically inserting or by-passing discrete transmission line segments
Data Source
AI summary
A communication unit comprises a controller and a radio frequency signal path having a plurality of delay elements operably coupled to a series of respective amplifier stages, wherein the controller is arranged to individually enable the respective amplifier stages. In response thereto a number of the plurality of delay elements are selectively inserted into or by-passed from the radio frequency signal path thereby adjusting a phase shift applied to signals provided through the radio frequency signal path.