Diplexer vs Duplexer : Understanding the Differences and Applications
Diplexer and duplexer are two critical components used in RF communication systems, yet they serve different purposes despite often being confused with each other. While both devices are used for managing multiple frequency bands and improving signal transmission efficiency, their applications and designs vary significantly. Understanding the key difference between diplexer and duplexer is essential for selecting the right component in wireless communication setups. This page delves into their functionality, structure and use cases, providing a clear comparison to help you distinguish between the two.
Diplexer
Definition : The device separates two different frequency bands in the receive path and combines them in the transmit path is known as diplexer. These frequency bands usually will be wide apart in frequency domain for diplexer to work satisfactorily. It is often referred as RF power combiner/divider with added functionality of filtering. Broadband Filters are used to pass appropriate bands at Tx and Rx path.
Example of diplexer:
Diplexer is used to separate/combine frequency bands of GSM900 and DCS 1800 systems.
It is also used in multiband design of mobile handset with multiple technologies GSM,CDMA,LTE.
As shown in the figure, diplexer does multiplexing and demultiplexing of wide frequency bands
with much appropriate difference. Figure shows L and H bands at S port.
As shown in the figure-1 there are two RF ports in diplexer other than output port, the device RF triplexer >> will have 3 ports other than one output port.
Duplexer
Definition : The device which allows allows use of the single antenna by both transmitter and receiver parts of a single device or two devices is known as duplexer. In other words duplexer is a device which couples the transmitter and receiver to the antenna while producing isolation between transmitter and receiver. There are two types of duplexer, one by using PIN diode switches and the other using circulators as shown. Both transmit and receive paths usually will have frequency bands very nearer, hence narrow band filters are used to separate these frequencies. Duplexer is often referred as 3-port RF circulator.
Duplexers are of two types viz. using PIN diode switches and using circulators as shown.
Example of duplexer:
It separates uplink (890-915MHz,Uplink-UL) and downlink (935-960MHz,Downlink-DL) frequency
bands in GSM900 system.
Difference between diplexer and duplexer
Let us summarize and compare diplexer vs duplexer.
➨Diplexer is three port passive device which permits sharing of common channel
between two devices operating in different bands. As mentioned above, both GSM900 and
DCS1800 can make use of single communication path and antenna using different
frequency bands. Two separate filters help them perform this task.
➨Duplexer is also three port device which permits sharing of single antenna
by two systems operating in very near bands. As mentioned above, both uplink and
downlink bands of a single device are being separated by duplexer using circulator like structure.
These terms are not interchangeable. They are designed for very different purposes. Following table mentions difference between diplexer and duplexer.
| Specifications | Diplexer | Duplexer |
|---|---|---|
| What is it ? | It consists of set of filters which allows separate processing of signals with widely differing frequencies. It separates two different bands in receive path and combines them in transmit path. | It consists of two filters (of bandpass type) which allows simultaneous transmission and reception within same band and using the same antenna. |
| Direction of operation | It usually operates with signals flowing in the same direction. | It usually operates with signals flowing both ways at the antenna. |
| Separation of bands on which it is operating | Operates on wide apart frequency bands | Frequency bands of Tx and Rx path are very nearer |
| Tx-Rx Isolation | 50 to 60 dB | 90 to 95 dB |
| Examples/Applications | Smart phone uses LC diplexer, other examples of diplexer are antenna splitter, DSL splitter, speaker crossover network | Smart phone uses SAW duplexer type |
Conclusion
In summary, diplexers and duplexers play unique roles in RF systems by enabling efficient frequency management and simultaneous signal transmission. A diplexer is designed to separate or combine different frequency bands, while a duplexer enables simultaneous transmission and reception on the same antenna by isolating the transmit and receive paths. Choosing between a diplexer and a duplexer depends on the specific requirements of the RF system, such as the need for frequency separation or simultaneous two-way communication. Understanding these differences ensures optimal performance and reduced interference in wireless communication networks.
Diplexer and Duplexer Manufacturers
Diplexer, duplexer and triplexer devices are widely used for test and measurement of
wireless modules compliant to standards such as WLAN, WiMAX, GSM, CDMA, LTE etc.
Following are the popular manufacturers of diplexer and duplexer devices.
• RTx Technology Co. Ltd., KOREA
• TriQuint Semiconductor Inc., USA
• Wainwright Instruments, GmbH
• Wireless Telecom Group Inc (Microlab) , USA and UK
• API Technologies Corp.
• RFMW Ltd, SAN JOSE, CA, USA
• Oscilent Corporation
• Murata Manufacturing Co. Ltd.
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