Multi-band Coupling Circuit with Identical Couplers
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Solution Overview
Problem
Multi-band radiofrequency transmission-reception systems face challenges in manufacturing complexity due to varying coupler sizes, directivity variations, and poor frequency selectivity, leading to parasitic reflections and measurement errors.
Innovation Solution
A multi-band coupling circuit with identical couplers for all channels, each with a network of filters and attenuators sized to match specific frequency bands, and resistive separators to ensure consistent impedance matching and improved directivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If different sized couplers are used for different frequency bands, then each coupler can be optimized for its specific frequency band, but manufacturing complexity increases and directivity varies between couplers
Solution Approach 1:
The patent applies a single universal coupler design that functions across multiple frequency bands (e.g., 700 MHz, 850 MHz, 1.9 GHz, 2.1 GHz) without requiring separate couplers for each band. This multi-functional approach eliminates the need for different sized couplers while maintaining performance across all bands, thereby reducing manufacturing complexity and ensuring consistent directivity.
2Adaptability or versatility
If couplers are transferred to insulating substrates, then integration with other circuits is enabled, but impedance matching becomes imperfect causing parasitic reflections
Solution Approach 1:
The patent introduces impedance matching networks as intermediary components between the coupler and the insulating substrate. These networks compensate for the impedance discontinuities introduced by the substrate, maintaining perfect impedance matching (50 ohms) even when the coupler is transferred to an insulating surface. This eliminates parasitic reflections while enabling circuit integration.
3Adaptability or versatility
If multiple antennas are connected to couplers, then multi-band operation is achieved, but mutual coupling between antennas distorts measurement results
Solution Approach 1:
The patent extracts and removes the measurement port from the antenna connection path. By separating the measurement function from the antenna interface, the patent eliminates the mutual coupling effects between antennas that would otherwise distort measurement results. This allows multi-band operation with multiple antennas while maintaining measurement accuracy.
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
The circuit (3) has a coupler (311) including a first conductive line provided between first and second ports (IN1, OUT1) connected to first and second terminals of a channel. The coupler includes a second conductive line arranged between third and fourth ports (CPLD, ISO). Attenuators (5) are arranged between the third port and a third terminal of the channel. A grid (4) of filters (481, 491) is provided between the fourth port and a fourth terminal of the channel. The filter grid filters signals outside frequency band of the channel.