Intermediate-frequency (IF) amplifiers are

amplifier An amplifier, electronic amplifier or (informally) amp is an electronic device that can increase the magnitude of a signal (a time-varying voltage or current). It is a two-port electronic circuit that uses electric power from a power su ...

stages used to raise signal levels in radio and television receivers, at frequencies intermediate to the higher

radio-frequency Radio frequency (RF) is the oscillation rate of an alternating electric current or voltage or of a magnetic, electric or electromagnetic field or mechanical system in the frequency range from around to around . This is roughly between the ...

(RF) signal from the antenna and the lower (baseband) audio or video frequency that the receiver is recovering.

Uses

IF amplifiers in

heterodyne receiver A superheterodyne receiver, often shortened to superhet, is a type of radio receiver that uses frequency mixer, frequency mixing to convert a received signal to a fixed intermediate frequency (IF) which can be more conveniently processed than ...

s apply gain in a frequency band between the input

radio frequency Radio frequency (RF) is the oscillation rate of an alternating electric current or voltage or of a magnetic, electric or electromagnetic field or mechanical system in the frequency range from around to around . This is roughly between the u ...

and output

audio frequency An audio frequency or audible frequency (AF) is a periodic vibration whose frequency is audible to the average human. The SI unit of frequency is the hertz (Hz). It is the property of sound that most determines pitch. The generally accepted ...

or video frequency, often following one stage of

RF amplifier A radio-frequency power amplifier (RF power amplifier) is a type of electronic amplifier that converts a low-power radio-frequency (RF) signal (electrical engineering), signal into a higher-power signal. Typically, RF power amplifiers are used ...

. This allows most of the gain in the form of a fixed-frequency amplifier, simplifying tuning. Compare to its predecessor, the tuned RF receiver. IF amplifiers might use

double-tuned amplifier A double-tuned amplifier is a tuned amplifier with transformer coupling between the amplifier stages in which the inductances of both the primary and secondary windings are tuned separately with a capacitor across each. The scheme results in a wi ...

s or staggered tuning to generate the appropriate frequency response needed. Some use more than one IF frequency.

Commonly used circuits

* Mutual inductance coupling: contains two windings that are joined by mutual inductance. * Shunt capacitance coupling: These circuits have a wide pass band. * composite IF transformers: receivers used for A-M and F-M receivers.

References

External links

{{Commonscat-inline, IF amplifiers Electronic amplifiers