U4488B Datasheet | TEMIC Semiconductors

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 plete 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 Figure 1. Block diagram Ordering Information Extended Type Number U4488B Package DIP16 Remarks TELEFUNKEN Semiconductors Rev. A2, 15-Jan-98 1 (9) Preliminary Information 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 characteristic is required for the vision and sound carrier. In case of L-standard, a bandpass filter with the center frequency at the L-sound carrier is used. The amplifier consists of three AC-coupled wideband IF stages. Each differential amplifier stage is gain controlled by the AGC (Automatic Gain Control) voltage, available at Pin 3. The output signal of the IF amplifier is then applied to the FPLL carrier generation, to the mixer for FM/NICAM signals and to the AM demodulator. The IF-AGC is derived from the average level of the AM carrier (L...