The Beken BK1198 is an all-silicon AM/FM/SW radio chip that uses entirely digital signal processing for the IF and bandpass functions. While this has been standard for VHF radios and TV sets for many years, it is only recently that it has become possible to use digital processing for AM reception.
Like most radio reciever chips, the BK1198 has a serial data control interface, but it can also be controlled using DC level sensing inputs. In that mode the tuning control is a simple potentiometer, and the BK1198 works out the rotational position of the pot (and thus the station to be received) from the pot voltage. Band selection is sone in a similar manner.
This gives an extremely easy means of building a high performance radio.