FM radio circuit
GENERAL DESCRIPTION
The TDA7000 is a monolithic integrated circuit for mono FM portable radios, where a minimum on peripheral components is important (small dimensions and low costs).
The IC has an FLL (Frequency-Locked-Loop) system with an intermediate frequency of 70 kHz. The i.f. selectivity is obtained by active RC filters. The only function which needs alignment is the resonant circuit for the oscillator, thus selecting the reception frequency. Spurious reception is avoided by means of a mute circuit, which also eliminates too noisy input signals. Special precautions are taken to meet the radiation requirements.
The TDA7000 includes the following functions:
• R.F. input stage
• Mixer
• Local oscillator
• I.F. amplifier/limiter
• Phase demodulator
• Mute detector
• Mute switch