Transmit-and-Receive Module Isolating Signals via Phase Shifter Correction
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Solution Overview
Problem
In mobile communication terminals, the sensitivity of received signals is decreased due to transmit signals superimposed on received signals, particularly when downlink and uplink carrier aggregation are simultaneously operated, causing noise interference between signals with close frequency bands.
Innovation Solution
A transmit-and-receive module is designed with phase shifter circuits and correction circuits to adjust impedance and generate canceling signals, ensuring that transmit signals are isolated from received signals, using duplexer configurations with specific filter characteristics to prevent signal superposition and enhance signal sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If carrier aggregation is used to simultaneously transmit and receive signals by using aggregated multiple component carriers, then communication speed is improved, but transmit signals may superimpose on received signals causing noise interference and decreasing sensitivity
Solution Approach 1:
The patent divides the frequency spectrum into distinct bands and assigns different filters to handle different frequency ranges. The first filter processes first frequency band signals while the second filter processes second frequency band signals, preventing overlap and interference between transmit and receive signals across different carriers
Solution Approach 2:
The patent introduces a canceller circuit as an intermediary component that receives the first transmit signal and generates a canceling signal to subtract from the received signal path. This actively removes the harmful transmit signal leakage from the receive path, resolving the interference problem while maintaining carrier aggregation benefits
2Adaptability or versatility
If the band of transmit signal is close to the band of received signal, then frequency utilization is improved, but transmit signal leakage increases causing noise for received signal
Solution Approach 1:
The patent applies different filter characteristics to different frequency bands. The first filter is optimized for the first frequency band with specific passband and stopband characteristics, while the second filter is optimized for the second frequency band. This localized optimization ensures that each filter effectively handles its designated band while minimizing leakage to other bands
Solution Approach 2:
The patent takes the harmful transmit signal that leaks through the receive filter and converts it into a useful canceling signal. The canceller circuit uses this leaked transmit signal to generate an equal and opposite signal that subtracts the interference from the received signal path, turning the harmful leakage into a beneficial cancellation mechanism
Data Source
AI summary
A transmit-and-receive module includes a power amplifier, a low-noise amplifier, first and second phase shifter circuits, and a correction circuit. The power amplifier amplifies power of first and second transmit signals. The low-noise amplifier amplifies first and second received signals without increasing noise. The first and second phase shifter circuits adjust impedance for the first received signal and that for the second received signal. The correction circuit supplies a canceling signal to an output node of the second phase shifter circuit. The canceling signal is used for canceling the first transmit signal passing through a receive filter.