The object of this invention is to demodulate received signals having different
received signal frequencies with the simple circuit configuration. With the present
invention, the fixed frequency signals are generated at the fixed PLL unit 310,
and simultaneously, the standard frequency signals corresponding respectively to
GSM/DCS received RF signals are generated at the channel PLL unit 330. And
using the image removal mixer 370 jointly to received RF signals, local
oscillation signals having local oscillation frequencies equal to the received
signal frequencies of the received RF signals respectively are formed from the
fixed frequency signals and the standard frequency signals for receiving. And since
the quadrature demodulators 254 and 264 demodulate the received RF
signals using corresponding local oscillation signals respectively, the circuit
configuration can be simplified by sharing the image removal mixer 370.
Thereby, receiving signals having different received signal frequencies can be
demodulated with the simple circuit configuration.