Multiband RF Circuit Switching Layout for Lower Transmission Loss
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Solution Overview
Problem
In multiband radio frequency power amplifying circuits, the transmission loss of radio frequency signals increases due to the ON-resistance of switches used to switch between different filters, which are necessary for amplifying and transmitting signals of various bands.
Innovation Solution
A radio frequency circuit design that includes multiple amplifying elements, transformers, and filters, with strategically placed switches to minimize the number of switches in the signal path, particularly ensuring no switch is in series for the highest frequency band, thereby reducing transmission loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If switches are arranged in series in the signal path to switch between different filters for multiband amplification, then the ability to transmit multiple bands is improved, but the transmission loss increases due to the ON-resistance of the switches
Solution Approach 1:
The patent divides the filter switching function into two independent parts: a first switch connected to ground for selecting between filters, and a second switch for the other end of the output coil. This segmentation allows the signal path to be optimized so that the path to the third filter (second band) does not require a series switch, thereby reducing transmission loss for that band while maintaining multiband capability.
Solution Approach 2:
The patent introduces a third filter as an intermediary element that receives signals from the output coil through a path that avoids series switches. The first switch acts as an intermediary control element that can connect or disconnect the third filter from ground without placing a switch in the direct signal path to the filter input, thus enabling band selection without increasing transmission loss.
2Adaptability or versatility
If multiple filters are used to correspond to different bands, then the multiband amplification capability is improved, but the device complexity increases
Solution Approach 1:
The first switch serves multiple functions: it can connect or disconnect different filters from the output coil, it can ground specific filters to exclude them from the signal path, and it can selectively enable the third filter without requiring a series switch in its path. This multi-functionality reduces the need for additional dedicated switches for each filter, thereby reducing overall device complexity while maintaining multiband capability.
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 configuration allows for efficient transmission of radio frequency signals across multiple bands with reduced loss, enabling a multiband radio frequency circuit and communication device with low signal attenuation.
Implementation Method 1
a transformer having an input side coil and an output side coil
Implementation Method 2
a first filter having a pass band that includes a first band; a second filter having a pass band that includes a second band; a third filter having a pass band that includes a third band
Data Source
AI summary
A radio frequency circuit includes power amplifiers, an input side coil and an output side coil, a filter whose pass band is a first band, a filter whose pass band is a second band, a filter whose pass band is a third band, a switch connected between ground and a path connecting one end portion of the output side coil and the filter, a switch connected between the ground and a path connecting the other end portion of the output side coil and the filter, a switch arranged in series in the path in between the switch and the filter, and a switch arranged in series in the path connecting the filter and a path connecting the switch and the switch, wherein no switch is arranged in series in the path.