| 摘要 |
In a frequency synthesizer of a TDMA cellular communication mobile unit, a reference pulse is supplied from a reference pulse source to a phase comparator whose output is coupled through an open/close loop mode switch to a loop filter which is connected to a VCO. A frequency divider produces a submultiple of the VCO frequency and supplies its output to the phase comparator. For power savings purposes, a controller first activates the reference pulse source and the frequency divider and operates the switch to establish a connection between the phase comparator and the loop filter. The controller then operates the frequency divider so that a channel is established between the mobile unit and a first cell site station, and then operates the switch to clear the connection and deactivates the reference pulse source and the frequency divider to allow signals to be exchanged between the mobile unit and the first cell site station during a transmit/receive slot of the channel in a power saving mode. The controller then activates the reference pulse source and the frequency divider, operates the switch to reestablish the connection, and operates the frequency divider during an idle slot of the channel to receive a signal from a second cell site station, and operates the frequency divider so that signals can be exchanged between the mobile unit and the first cell site station during a subsequent transmit/receive slot of the channel. |
