Transceiver Front-End Isolation Using On-Chip Transmission Lines
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Solution Overview
Problem
Existing transceiver front-ends for communication devices face challenges in providing effective isolation between transmitters and receivers, particularly in frequency division duplex communication systems, due to interference from strong transmitter signals and the need for costly and bulky off-chip duplexers, as well as complex on-chip solutions that require impedance tracking and result in power loss.
Innovation Solution
The implementation of a transceiver front-end with transmit and receive frequency blocking arrangements using networks of passive components, including transformers and filter arrangements, which block unwanted frequency signals while allowing desired signals to pass through, thereby isolating the transmitter and receiver without the need for impedance matching or tracking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If off-chip acoustic wave duplex filters are used to provide isolation between transmitter and receiver, then isolation performance is improved, but device size and cost increase
Solution Approach 1:
The patent extracts the isolation function from traditional off-chip acoustic wave duplex filters and implements it using on-chip transmission line structures. The through-hole transmission lines and planar transmission lines are integrated directly into the chip substrate, eliminating the need for bulky off-chip components while maintaining the isolation function between transmitter and receiver.
Solution Approach 2:
The patent replaces the mechanical acoustic wave filter structure with an electromagnetic transmission line structure. Instead of using acoustic waves propagating through physical filter media, the invention uses electromagnetic signals traveling through transmission lines with specific impedance characteristics to achieve the same isolation effect in a planar, integrated format.
2Reliability
If off-chip acoustic wave duplex filters are used to provide isolation between transmitter and receiver, then isolation performance is improved, but cost increases
Solution Approach 1:
The patent merges the isolation function with the existing RF signal transmission path by integrating transmission lines directly into the chip. The through-hole transmission lines connect the antenna interface to both the transmitter and receiver, providing isolation as an inherent feature of the integrated structure rather than as a separate component, thereby reducing overall system cost.
Solution Approach 2:
The transmission line structure serves multiple functions simultaneously: it provides signal transmission paths for both transmitter and receiver, establishes impedance matching, and provides isolation between the two ports. This multi-functionality eliminates the need for separate isolation components, reducing both cost and complexity.
3Reliability
If fixed frequency duplexers are used to provide isolation, then isolation at specific frequencies is improved, but adaptability to multiple frequency bands deteriorates
Solution Approach 1:
The patent implements dynamic frequency adaptability by making the transmission line electrical lengths可调 (tunable). By adjusting the electrical length of the through-hole transmission lines and planar transmission lines, the isolation characteristics can be optimized for different frequency bands, allowing the same physical structure to adapt to multiple operating frequencies rather than being fixed at a single frequency.
Solution Approach 2:
The patent changes the electrical parameters (length, impedance) of the transmission lines to adapt to different frequency bands. By modifying the physical dimensions or electrical characteristics of the transmission lines, the system can maintain effective isolation across multiple frequency bands without requiring separate duplexers for each band.
4Reliability
If cancellation-based isolation is used, then isolation capability is improved, but circuit complexity increases due to impedance tracking requirements
Solution Approach 1:
The transmission line structure provides isolation as an inherent property of its design rather than requiring active cancellation mechanisms. The specific impedance and electrical length of the transmission lines naturally provide the isolation function without needing additional control circuits or impedance tracking systems, thereby reducing overall circuit complexity.
5Reliability
If dummy load cancellation is used, then interference cancellation is improved, but power loss increases by at least 3 dB
Solution Approach 1:
The patent extracts the isolation function from the signal path in a way that does not require dissipating signal energy in dummy loads. Instead of using resistive cancellation that burns power, the transmission line structure provides isolation through its inherent impedance characteristics, allowing signals to pass through without significant power loss while still achieving the desired isolation effect.
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 provides efficient isolation between transmitter and receiver, reduces power loss, and is insensitive to antenna impedance variations, offering a compact, cost-effective, and tunable solution for multiple frequency bands.
Implementation Method 1
a first transformer having a first primary winding and a first secondary winding
Implementation Method 2
a first filter arrangement connected to a second node of the first side of the first transformer and adapted to have a higher impedance value at a transmit frequency than at a receive frequency
Data Source
Figure 1~3b
Figure 4~5
Figure 6~7
AI summary
A transceiver front-end of a communication device is disclosed. The transceiver front-end is connectable to a signal transmission and reception arrangement adapted to transmit a transmit signal having a transmit frequency and to receive a receive signal having a receive frequency, to a transmitter adapted to produce the transmit signal, and to a receiver adapted to process the receive signal. The transceiver front-end comprises at least one of a transmit frequency blocking arrangement and a receive frequency blocking arrangement. The transmit frequency blocking arrangement has a blocking frequency interval associated with the transmit frequency and a non-blocking frequency interval associated with the receive frequency, and is adapted to block passage of transmit frequency signals between the signal transmission and reception arrangement and the receiver. The receive frequency blocking arrangement has a blocking frequency interval associated with the receive frequency and a non-blocking frequency interval associated with the transmit frequency, and is adapted to block passage of receive frequency signals between the signal transmission and reception arrangement and the transmitter. At least one of the transmit frequency blocking arrangement and the receive frequency blocking arrangement comprises a network of passive components comprising at least one transformer and a filter arrangement adapted to have a higher impedance value in the blocking frequency interval than in the non-blocking frequency interval.