Sma Fm Stereo Receiver

111ESEeptembe„987 SMA FM STEREO RECEIVER Surface mount chip Type TDA7021T from Valvo/Mullard is the recently introduced stereo version of the TDA7000 FM receiver decribed in (1). Together with the TDA7040T stereo decoder, and the TDA7050T AF amplifier-also SMA integrated circuits-the TDA7021T enables building a portable stereo receiver for the FM broadcast band (88 to 108 MHz). The internal organization of the TDA7021T is similar to that of the TDA7000, and appears in Fig. 1. The TDA7021T is stereo compat- ible and has a circuit for in- dicating the relative signal strength. The chip is housed in a SOT109A enclosure for sur- face mount assembly. The RF input signal applied to pin 12 is amplified in an RF stage, and subsequently mixed down to the intermediate frequency (IF) with the aid of an externally tuned local oscillator. The IF signal is filtered, given a par- ticular bandwidth, once more filtered, and limited. The limiter drives the field strength indi- cation circuit,...