LM3189 FM IF
LM3189 FM IF System
The LM3189N is a monolithic integrated circuit that provides all the functions of a comprehensive FM IF system. The block diagram of the LM3189N includes a three stage FM IF amplifier/limiter configuration with level detectors for each stage, a doubly balanced quadrature FM detector and an audio amplifier that features the optional use of a muting (squelch) circuit.
The advanced circuit design of the IF system includes desirable deluxe features such as programmable delayed AGC for the RF tuner, an AFC drive circuit, and an output signal to drive a tuning meter and/or provide stereo switching logic. In addition, internal power supply regulators maintain a nearly constant current drain over the voltage supply range of a8.5V to a16V.
The LM3189N is ideal for high fidelity operation. Distortion in an LM3189N FM IF system is primarily a function of the phase linearity characteristic of the outboard detector coil. The LM3189N has all the features of the LM3089N plus additions.
Exceptional limiting sensitivity: 12 mV typ at b3 dB point
Low distortion: 0.1% typ (with double-tuned coil)
Single-coil tuning capability
Improved (S a N)/N ratio
Externally programmable recovered audio level
Provides specific signal for control of inter-channel muting (squelch)
Provides specific signal for direct drive of a tuning meter
On channel step for search control
Provides programmable AGC voltage for RF amplifier
Provides a specific circuit for flexible audio output
Internal supply voltage regulators
Externally programmable ON channel step width, and deviation at which muting occurs
IF In Bypass
IF In Bypass
Positive Supply Voltage
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