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RF vs IF

This page describes difference between RF(Radio Frequency) and IF(Intermediate Frequency). It also explains how one frequency is converted to the other and viceversa.

RF vs IF

Both the terms are used in wireless system, IF to RF and RF to IF conversion can be done using a device called mixer. The same conversion can be achieved by way of single conversion or dual conversion.

IF to RF conversion is achieved using a RF device called Up-converter. Refer design of up converter using mixers, LOs, amplifiers and other discrete components. This concept is used to convert IF signal to RF signal.

RF to IF conversion is achieved using a RF device called Down-converter. Heterodyne and homodyne receiver architectures are used to convert modulated RF signal to IF signal. Superheterodyne uses 10.7MHz as first IF and 470KHz as second IF.

Following table mentions intermediate frequencies(IF) typically used for different applications such as RF test Equipments, Radar, Satellite equipments, microwave equipments, AM/FM radio, television(TV) etc.

Type of application Intermediate
Frequency value
RF test equipments 21.4MHz,
160MHz,
310.7MHz
Radar 30MHz
Satellite Equipments 70MHz for C band
up converter
and down converter;
140MHz for Ku Band;
950 to 1450MHz
for L Band
Equipments and Systems
Microwave Equipments 70MHz, 75MHz, 250MHz
AM Radio(Values are in KHz) 450,455,460,
465,467,470,
475,480
FM Radio 262KHz,455KHz,
1.6MHz,5.5MHz,
10.7MHz,10.8MHz,
11.2MHz,11.7MHz,
11.8MHz,21.4MHz,
75MHz,98MHz.
Analog Television 41.25MHz for audio
and 45.75MHz for video
in TV system M;
33.4MHz(Aural)
and 38.9MHz(Visual)
in TV system B
Broadcast Receiver 110KHz

Following block diagram converts IF frequency to RF frequency. This circuit is known as IF to RF converter or RF up converter.

RF frequency converter BD

The circuit consists of discrete rf components such as RF mixers, rf filters, rf isolators, chip resistors and capacitors, MMICs etc. Refer RF Frequency Converter design>> and RF Transceiver design and development>> for more information.

What is Difference between

difference between FDM and OFDM
Difference between SC-FDMA and OFDM
Difference between SISO and MIMO
Difference between TDD and FDD
Difference between 802.11 standards viz.11-a,11-b,11-g and 11-n
FDM vs TDM
RF heterodyne versus homodyne receiver
SCPC Vs. MCPC
Diplexer versus Duplexer
Sensitivity Vs. selectivity

RF RELATED LINKS

stripline basics and types   Microstrip line variants   Slotline basics and types   Finline basics   CPW(Coplanar Waveguide) basics   RF converter design   C band RF Transceiver basics   RF filter design   RF vector Signal generation/analysis   Microstrip line basics  

RF and Wireless Terminologies