Overview

Being developed for FM IF System, LA1231 is a highly integrated circuit in which almost all functions are contained concerning the FM tuner IF stage. The block diagram of equivalent circuit is shown below. Usual peripheral circuits are shown also in examples of application circuits.

Functions

• IF amplification, Limiter.

• AF preamplifier.

• Muting at the detuning.

• AFC tuning meter drive output.

• Inverting circuit for muting drive voltage.

• Quadrature detection.

• Muting at weak.

• Signal meter drive output.

• Delay AGC output.

• IF amplifier stop circuit.