Fast acquisition circuit for a phase locked loop
Phase-locked loop with switchable loop filter
Phase detector output stage for phase locked loop
Digital signal receiver having a dual bandwidth tracking loop
Synchronized frequency synthesizer with high speed lock
Frequency synthesizer with improved priority channel switching
Radio transceiver having an adaptive reference oscillator
Reuse groups for scan monitoring in digital cellular systems Patent #: 4866710
ApplicationNo. 710637 filed on 06/05/1991
US Classes:370/345, Combining or distributing information via time channels375/327, Phase locked loop375/328, Including switching or gating (digital circuits)455/76, Synthesizer455/260Phase lock loop or frequency synthesizer
ExaminersPrimary: Olms, Douglas W.
Assistant: Jung, Min
Attorney, Agent or Firm
International ClassesH04B 001/40
AbstractA communication device (508) for use in a Time Division Multiplex (TDM) communication system (500) includes a transmitter, a receiver, and a frequency scanner for quickly scanning the radio frequency communication channels to determine an available channel. The communication device (508) also includes a phase locked loop (100) for providing a reference signal for the communication device (508) and locking to the available channel. This phase locked loop (100) includes a Voltage Control Oscillator (VCO) (104) having a control signal input (103). The phase locked loop (100) also includes a first filter (110) and a second filter (108). The first filter (110) has a wide frequency response. The second filter (108) includes a storage element (222) and has a narrow frequency response. The phase locked loop (100) also includes a switching circuit (106) which determines which one of the two filters (110, 108) gets coupled to the voltage control oscillator (104).