The BA1442A is an AM radio and FM IF stereo system IC developed for radio cassette players. The FM circuit is comprised of a differential IF amplifier, a double-balance type quadrature detector, and a PLL-type stereo MPX circuit. The AM circuit is comprised of a local oscillator, a double-balanced mixer, an IF amplifier, a detector, and an AGC circuit.
  
Features
1) The “S” curve characteristic of the FM detector can
   be used for upper heterodyne (“N” curve) operation.
2) Audio high cut and low cut can be used to improve the
   AM fidelity.
3) A reference voltage supply is provided to ensure
   good frequency stability in the shortwave bands.
4) Good FM stability.
5) Built-in damping resistor (3.3kΩ) for the quadrature
   coil.  
6) The FM MPX uses a Laser Locked Loop, making
   adjustment of the VCO and addition of external
   components unnecessary.
7) Built-in forced monaural function for the MPX (VCO
   stops, LED off).
8) VCO of the MPX is switched off during AM operation.
9) The stereo indicator pin has a constant drive current,
   and a current limiting resistor is not required.
10) Few external components required.  

Applications
   Radio cassette players