RF Transceiver Switch Layout for Lower Transmit Insertion Loss
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Solution Overview
Problem
Multi-band transceivers experience significant power loss due to the insertion loss caused by PIN diode switches in the transmit path, which affects battery life in handheld devices, despite minimal impact in the receive path.
Innovation Solution
The implementation of a switching arrangement that reduces the number of PIN diode switches in the transmit path from three to two by selectively controlling the series-shunt configuration, allowing only two PIN diode switches to be present when switching between different harmonic filters, thereby minimizing power loss and extending battery life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If three PIN diode switches are used in the transmit path for switching between harmonic filters, then filter switching capability is achieved, but power consumption increases by approximately 1.4 Watts of DC power
Solution Approach 1:
The patent extracts one PIN diode switch from the transmit path by utilizing the shunt diode of a band switch network to perform the switching function. This removal reduces the total number of PIN diode switches from three to two, directly decreasing power consumption while maintaining filter switching capability through the remaining series diode and the repurposed shunt diode.
Solution Approach 2:
The shunt diode of the band switch network is given a dual function: it continues to perform its original band switching role while also serving as the third switch in the transmit path for harmonic filter selection. This multi-functionality eliminates the need for a dedicated third PIN diode switch, reducing overall power consumption.
2Adaptability or versatility
If PIN diode switches are used in the transmit path, then harmonic filter switching is enabled, but insertion loss occurs affecting battery life
Solution Approach 1:
By removing one PIN diode switch from the transmit path and redistributing switching functions among the remaining two switches, the patent reduces the cumulative insertion loss caused by multiple switches in series. The band switch network's shunt diode is configured to provide low insertion loss when conducting, compensating for the reduced number of switches.
3Reliability
If series-shunt configuration PIN diode switches are used to achieve high isolation, then RF signal isolation is improved, but power consumption increases
Solution Approach 1:
The shunt diode performs dual functions: maintaining high isolation through its series-shunt configuration with the series diode, and simultaneously enabling harmonic filter switching. This multi-functionality achieves the required RF isolation performance without adding extra PIN diode switches that would increase power consumption.
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 reduces power consumption by approximately 1.4 Watts of DC power, significantly extending battery life in handheld transceivers while maintaining system performance, as the receive path still achieves adequate filtering with three series diodes.
Implementation Method 1
A PIN diode is a diode with a wide, un-doped or lightly doped intrinsic semiconductor region that resides between a p-type semiconductor and an n-type semiconductor region. Under conditions where the PIN diode has zero bias or is reversed biased, it has a relatively low capacitance such that it presents a high insertion loss to a radio frequency (RF) signal. However, when the PIN diode is forward biased with sufficient current it will have only minimal resistance to RF signals (e.g. about 1 ohm).
Implementation Method 2
A series-shunt configuration PIN diode switch is conventionally used to achieve a relatively high isolation, which may be particularly important in high frequency applications, for example at or above 1GHz. The series diode and shunt diode of a particular switched path must be forward and reversed biased complementarily to minimize insertion loss and maximize isolation.
Implementation Method 3
The implementation of a switching arrangement that reduces the number of PIN diode switches in the transmit path from three to two by selectively controlling the series-shunt configuration, allowing only two PIN diode switches to be present when switching between different harmonic filters, thereby minimizing power loss and extending battery life.
Data Source
Figure 1
Figure 2
Figure 3A~3B
AI summary
Wireless transceiver includes a plurality of RF filters. A first band switching network includes a first plurality of RF switches to selectively direct transmitter RF energy to a selected RF filter. A second band switching network includes a second plurality of RF switches which selectively controls which of RF filter is connected to an antenna port. A receiver RF switch is connected to at least one of the RF filters and to a receiver input to selectively permit the received RF energy arriving at one RF filter to be communicated to the receiver. Each RF switch is a PIN diode type with at least one series diode provided along a signal path. No more than two PIN diodes are present in the signal path between the common transmitter port and the common antenna port when any of the RF filters is in use.