Off-Chip Transceiver Cancellation Using External Impedance Matching
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Solution Overview
Problem
Existing transceiver circuits face challenges in effectively suppressing transmit signals from reaching the receive section without using large or expensive filters, particularly due to difficulties in properly balancing the impedance of the antenna, especially when implemented on integrated circuits.
Innovation Solution
A transceiver circuit with a cancellation path comprising tunable filters and a balancing impedance circuit, where the cancellation path is configured to generate a signal that cancels transmit signals in the receive path, utilizing external connection pads and adjustable filters to adapt to varying antenna impedances and configurations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If large or expensive filters are used to suppress transmit signals from reaching the receive section, then signal suppression is improved, but device complexity and cost increase
Solution Approach 1:
The patent divides the cancellation function into multiple segments: an on-chip cancellation circuit that generates the cancellation signal, external passive components connected via pads that shape the signal, and a combination path that merges the cancellation signal with the receive path. This segmentation allows complex suppression functionality to be achieved without requiring a single large complex filter on the IC.
Solution Approach 2:
The patent introduces external passive components (resistors, capacitors, inductors) connected to external pads as intermediaries between the on-chip cancellation circuit and the receive path. These intermediary components enable precise impedance matching and signal shaping without requiring complex integrated filter structures, thus reducing on-chip complexity while maintaining suppression effectiveness.
2Ease of manufacture
If impedance balancing is implemented on an integrated circuit, then integration is improved, but impedance matching precision deteriorates due to difficulty in properly balancing antenna impedance
Solution Approach 1:
The patent extracts the precise impedance matching function from the integrated circuit by providing external connection pads that allow external passive components to be connected. The on-chip circuit provides the cancellation signal generation, while the external components handle the precise impedance matching, combining the advantages of both integrated and discrete implementations.
Solution Approach 2:
The patent implements different quality levels in different parts of the system: the on-chip cancellation circuit provides basic cancellation functionality with standard integration, while the external passive components provide high-precision impedance matching where it is most needed. This local differentiation optimizes both integration and precision without compromising either.
3Adaptability or versatility
If tunable filters and balancing impedance circuits are used in the cancellation path, then adaptability to varying antenna impedances is improved, but device complexity increases
Solution Approach 1:
The patent implements tunable filters with adjustable cutoff frequencies and Q-factors that can be configured via control signals or resistors. This dynamic adjustability allows the cancellation circuit to adapt to different antenna impedances and operating conditions, providing versatility without requiring multiple fixed circuits for each scenario.
Data Source
AI summary
A transceiver circuit implemented on one or more integrated circuits, the transceiver comprising: a signal transmitter for forming a radio signal for transmission; a signal receiver for performing receive processing on a received radio signal; and a cancellation circuit for at least partially cancelling components of the signal for transmission in the signal receiver, the cancellation circuit being arranged to receive an input from the signal transmitter and to provide a cancellation output to the signal receiver, the cancellation circuit being configured to form the cancellation output in dependence on both the input from the signal transmitter and a response received from a first external connection pad of one of the integrated circuits.