U4488B

U4488B Quasi-Split Sound Circuit and AM Demodulator Description The U4488B is an integrated bipolar circuit for full multistandard sound IF signal processing in TV/VTR and Multimedia applications. It supplies AM signals as well as FM/NICAM sound IF signals and thus allows the design of a universal sound IF module for various applications. The U4488B has the same performance like the U4468B, with the additional feature of a second symmetrical IF input. Features D 5-V supply voltage; low power consumption D Gain-controlled 3-stage wideband IF amplifier D Active carrier generation by FPLL principle (frequency-phase-locked-loop) for true quadrature demodulation D Complete alignment-free AM demodulator D Switchable amplitude detector for gain control, which operates as a peak detector for FM sound and as a mean level detector for AM sound D Two symmetrical IF inputs Block Diagram IF1/IF2 S3 11 1 2 IF-Amp 12 Intercarrier (FM) 4 14 REF FPLL VS Loop filter 5 0° 90° VCO 9 8 VCO IF FM IF AM 15 16 IF-Switch Mean 3 AGC Peak level 13 IF AGC Mean/peak 7 S1 Mute AM-Det 6 AF(AM) 10 S2 13789 Figure 1. Block diagram Ordering Information Extended Type Number U4488B Package DIP16 Remarks TELEFUNKEN Semiconductors Rev. A2, 15-Jan-98 1 (9) Preliminary Information U4488B Circuit Description IF Amplifier and AGC The symmetrical IF input signal from the external SAW filter is fed to the Pins 1 and 2 resp. Pins 15 and 16. For FM/NICAM application, a SAW filter with double bandpass ch...