In a mobile communication system, a mobile station located in an area using an analog system receives information for synchronization from a base station situated in the above area. On moving from the area using an analog system to an area using a CDMA (Code Division Multiple Access) area, the mobile station acquires a pilot channel from a base station located at the CDMA area. For this purpose, the mobile station generates a phase set signal on the basis of the information received in the analog system area. The phase set signal resets an I-phase and a Q-phase spread code generator included in a serial search acquisition circuit for acquiring the pilot channel. As a result, spread codes output from the spread code generators are causes to coincide in phase with a spread code used to spread a signal being received over the pilot channel. This allows the mobile station to acquire the pilot channel in the CDMA system area in an extremely short period of time.

A CDMA transmitter having a variable gain circuit inserted between a transmitter mixer and a transmitter antenna. The gain is controlled in response to the RF output power so that the spurious emission level at the maximum RF output power and that at output power reduced by a predetermined amount can be both satisfied. This makes it possible to increase the degree of freedom of choosing circuit components in the RF stage.

A wireless telecommunication equipment having a receiver portion and a transmitter portion. An automatic gain control amplifier having a gain varied in accordance with an automatic gain control signal input thereto is located in the receiver portion of the equipment, and a transmission power control amplifier having a gain varied in accordance with an open loop control signal input thereto is located in the transmitter portion of said equipment. The automatic gain control and the transmission power control amplifiers have the same operating characteristics.