I have a ciruit diagram of an AM RECEIVER (118Mhz-136Mhz) in which the IC CA3075(FM IF AMPLIFIER LIMITER) and CA3012(FM IF WIDEBAND AMPLIFIER) are being used. I dont get it why are FM ICs being used in an AM receiver.Please help.
Without referring to the specific usage of the chips in the AM receiver, the question is about meaningless. CA3075 might be e.g. used for an AFC circuit,
The CA3012 is a linear amplifier, so it can be used for any modulation. Limiting amplifiers like CA3075 are only suitable for other than AM. By the way, the frequency band 118-136 MHz is mostly used for NBFM (narrow-band FM) signals, so your receiver may not be an "AM" type.
I agree. CA3012 cannot be used for AM demodulation at all. The only internal stage that can be used in a AM receiver is the audio preamplifier, which is available at pin 14 and pin 12.