Multi-channel signal processing circuit formed in a semiconductor integrated circuit

A system for enabling a use of fewer terminals than a conventionally required number of terminals for an integrated circuit chip, said system comprising:

• means first in a semiconductor chip for providing signal processing functions in different frequency bands, the signal processing functions in one of said frequency bands being AM radio reception, the signal processing functions in another of said frequency bands being FM radio reception;
• second means connected to one of said fewer terminals and external to said integrated semiconductor chip for modifying said functions, said external means comprising an inductive element of a tuned circuit;
• and
• third means coupled to said first means and said one terminal for modifying said functions in response to an application of power via said second means to said one terminal, said modification comprising a shifting of said functions between said AM and FM reception.

A system for enabling a use of fewer terminal than a conventionally required number of terminals for an integrated circuit chip, said system comprising:

• first means in a semiconductor chip for providing signal processing functions in different frequency bands, the signal processing functions in one of said frequency bands being AM radio reception, the signal processing functions in another of said frequency bands being FM radio reception;
• second means connected to one of said fewer terminals and external to said integrated semiconductor chip for modifying said functions, said external means including an inductive element which is at least one winding in an intermediate frequency transformer;
• and
• third means coupled to said first means and said one terminal for modifying said functions in response to an application of power via said second means to said one terminal, said modification comprising a shifting of said functions between said AM and FM reception.

A method of processing electronic signals comprising the steps of:

• a. applying signals to be processed to terminals on a housing of an integrated semiconductor chip;
• b. selectively processing, in said chip, said signals in AM or FM frequency bands;
• c. selectively and inductively coupling a voltage from a power supply to at least one of said terminals, said selective and inductive coupling being performed externally of said semiconductor chip;
• d. detecting the appearance of said voltage from said power supply when applied in step (c);
• and
• e. switching signal processing within said semiconductor chip between AM reception and FM reception in response to the voltage detection of step (d).

A system comprising:

• an integrated circuit chip having a plurality of terminals;
• means in said integrated circuit chip for providing signal processing functions in different frequency bands;
• means external to said integrated circuit chip for selectively supplying a voltage from a power supply line through an inductive element to one of said terminals;
• and
• means in said integrated circuit chip and coupled to said one terminal for shifting said functions between said different frequency bands in response to said voltage.