diplexer vs duplexer | difference between diplexer and duplexer

This page compares diplexer vs duplexer and describes difference between diplexer and duplexer. It explains basics of diplexer and duplexer in RF wireless communication system.


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. This diplexer vs duplexer comparison will help to use them according to their functionality in wireless system. For difference between RF diplexer and RF multiplexer, refer microwave multiplexer vs diplexer.

RF diplexer

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.


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.

RF duplexer

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

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.
• Oscilent Corporation
• Murata Manufacturing Co. Ltd.

What is Difference between

Following pages mention difference between RF power combiner and divider, 4 port circulator vs 3 port circulator, TDD vs FDD, FDM vs TDM and so on.
RF Isolator vs RF Circulator
RF circulator basics
4 port vs 3 port circulator
Power Divider vs Power Combiner
difference between FDM and OFDM
Difference between TDD and FDD
Fixed wimax vs mobile
wibro vs mobile wimax

RF and Wireless Terminologies