Phased Array Transmitter Spurious Signal Suppression
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Phased array transmitters face challenges in efficiently suppressing unwanted spurious signals, particularly at high microwave frequencies where space constraints and frequency differences complicate band-pass filtering, limiting communication system capacity.
Innovation Solution
The solution involves independently adjusting intermediate frequency (IF) and local oscillator (LO) phase shifts in each transmitting branch of a phased array transmitter to control and suppress unwanted spurious signals without affecting the wanted RF signal, using a combination of IF and LO phase shifters to achieve omnidirectional beam patterns for spurious signals, thereby reducing interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If band-pass filters are used to suppress unwanted spurious signals in each transmitting branch, then spurious signal suppression is improved, but device complexity and space requirements increase
Solution Approach 1:
The invention extracts the spurious signal suppression function from the traditional band-pass filter approach and implements it through a separate suppression signal generation path. Instead of relying solely on bulky passive filters in each transmitting branch, the system generates suppression signals that are combined with the main RF signals to cancel out spurious components, thereby reducing the filtering burden on individual branch filters
Solution Approach 2:
The band-pass filters are made to serve dual functions: their primary function of passing the desired RF signal and an additional function of suppressing spurious signals when combined with the suppression signals from the separate path. This multi-functionality reduces the need for overly complex filters in each branch while achieving comprehensive spurious signal suppression
2Object-affected harmful factors
If bulky band-pass filters are placed behind each antenna element for spurious signal suppression, then spurious signal suppression is improved, but the area occupied by each channel increases
Solution Approach 1:
The spurious signal suppression function is segmented from the main RF signal path and implemented through a separate, parallel path. This segmentation allows the suppression function to be distributed across multiple transmitting branches without requiring each branch to accommodate large filter components, thereby reducing the area occupied by each channel while maintaining effective suppression
Solution Approach 2:
Suppression signals act as intermediaries that mediate between the main RF signal path and the spurious signal components. These intermediary suppression signals are generated separately and combined with the main signals to achieve cancellation of spurious components, eliminating the need for large passive filters in each channel and reducing overall channel area
3Ease of manufacture
If traditional filtering methods are used for spurious signal suppression, then implementation simplicity is maintained, but suppression effectiveness decreases
Solution Approach 1:
The invention merges the traditional filtering approach with an active suppression signal generation approach. The suppression signals are generated by processing the IF signals through phase shifters and frequency converters, then these suppression signals are combined with the main RF signals. This combination of traditional and active methods achieves superior suppression effectiveness while maintaining implementation simplicity through modular architecture
Solution Approach 2:
The suppression signal generation path introduces dynamic control through adjustable phase shifters that can be tuned to optimize suppression effectiveness for different operating conditions. This dynamic adjustment capability allows the system to adapt to varying spurious signal characteristics while maintaining a relatively simple overall implementation structure
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 approach effectively reduces interference from unwanted spurious signals, maintaining the desired RF signal integrity without increasing space requirements, as demonstrated by simulated antenna performance showing reduced peak power density and antenna gain for spurious emissions.
Implementation Method 1
Transmit beamforming in a phased array transmitter is accomplished by introducing phase shifts in each transmitting branch such that the output signals produce a wavefront in a certain direction
Implementation Method 2
a mixer configured for mixing the phase shifted IF signal with a phase shifted local oscillator signal to provide an RF signal as output
Data Source
Figure 1A
Figure 1B
Figure 2A
AI summary
The present invention describes a phased array transmitter and a method for beamforming. The phased array transmitter comprises a plurality of transmitting branches configured for up-converting an IF signal to an RF signal with a desired RF phase shift. Each transmitting branch is configured for phase shifting the IF signal with a first phase shift and the LO signal with a second phase shift such that the combined first and second phase shift is the desired RF phase shift of the transmitting branch.