Transceiver Front-End Isolation Using Active Cancellation
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Solution Overview
Problem
Current transceiver front-ends for communication devices face challenges in providing effective isolation between transmitters and receivers, particularly in multi-band systems, due to the complexity and inefficiency of existing solutions like duplexers and balance networks, which require tracking of antenna impedance and result in signal loss.
Innovation Solution
A transceiver front-end design incorporating transmit and receive frequency suppression filter arrangements and cancellation arrangements, which use impedance or transconductance to suppress unwanted signals, allowing for on-chip implementation and reduced power loss without the need for transformers or dummy loads.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If duplexers 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 replaces mechanical/acoustic wave duplex filters with electrical balance networks and cancellation circuits implemented on-chip. This substitution of mechanical filtering systems with electrical circuits achieves the same isolation function while dramatically reducing device size and enabling integration.
Solution Approach 2:
The patent combines multiple isolation mechanisms (electrical balance network and active cancellation circuits) into a single integrated on-chip system. This merging of functions achieves effective isolation without requiring separate off-chip components, reducing overall device size.
2Reliability
If duplexers are used to provide isolation between transmitter and receiver, then isolation performance is improved, but cost increases
Solution Approach 1:
The patent replaces expensive off-chip acoustic wave duplex filters with standard electrical components (inductors, capacitors, resistors) and cancellation circuits that can be manufactured using conventional semiconductor processes, significantly reducing cost.
Solution Approach 2:
The patent uses standard, inexpensive semiconductor components instead of specialized, costly duplex filter components. The cancellation circuits use ordinary resistors and active devices that are cheap to manufacture in volume.
3Reliability
If balance network with dummy load is used for multi-band isolation, then isolation is achieved, but signal power loss increases
Solution Approach 1:
The patent employs active cancellation circuits that sense the transmit signal and generate an inverted copy to cancel out interfering signals at the receiver. This feedback-based cancellation achieves isolation without dissipating signal power in dummy loads.
Solution Approach 2:
The patent converts the harmful transmit signal that would otherwise interfere with reception into a useful cancellation reference. By using the transmit signal itself to generate the cancellation waveform, the system turns the interference source into the solution, avoiding power loss in dummy loads.
4Reliability
If balance network is used for multi-band isolation, then isolation is achieved, but device complexity increases
Solution Approach 1:
The patent designs cancellation circuits and filter networks that operate across multiple frequency bands simultaneously using the same hardware structure. This universal design achieves multi-band isolation without requiring separate circuits for each band, reducing overall complexity.
Data Source
AI summary
A transceiver front-end for a communication device 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. The transceiver front-end is also connectable to a transmitter adapted to produce the transmit signal, and to a receiver adapted to process the receive signal. The transceiver front-end comprises a transmit frequency suppression filter arrangement and a receive frequency suppression filter arrangement. The transmit frequency suppression filter arrangement is adapted to suppress transfer of a signal having the transmit frequency and to pass a signal having the receive frequency. The receive frequency suppression filter arrangement is adapted to suppress transfer of a signal having the receive frequency and to pass a signal having the transmit frequency. The transceiver front-end also comprises a transmit frequency cancellation arrangement and a receive frequency cancellation arrangement. The transmit frequency cancellation arrangement is adapted to produce a first cancellation signal for cancellation, at receiver nodes, of a suppressed signal having the transmit frequency, transferred by the transmit frequency suppression filter arrangement. The receive frequency cancellation arrangement is adapted to produce a second cancellation signal for cancellation, at signal transmission and reception arrangement nodes of a suppressed signal having the receive frequency, transferred by the receive frequency suppression filter arrangement. Corresponding transceiver, communication device and method are also disclosed.