Raytheon Company

Sam H Moy

Jaime E Kardontchik

Jack P Guedj

A transceiver integrated circuit including a transmitter section having a phase-locked loop with an oscillator to provide an output at a predetermined transmission frequency, and a receiver section having a phase-locked loop with an oscillator used to provide a recovered clock from an incoming data signal. In a second mode when no incoming data is being received, the receiver oscillator is controlled in accordance with the transmitter oscillator to operate the receiver oscillator at the expected frequency of future data. Therefore, when data is received, the receiver oscillator is at the same approximate frequency as the incoming data thereby enabling fast acquisition by merely adjusting the phase of the receiver oscillator to the incoming data. In particular, the receiver and transmitter oscillators are identical current controlled oscillators that are operated in the second mode at the same approximate frequency by feeding the receiver oscillator with a current that is substantially equal to the loop current controlling the transmitter oscillator. Further, to provide higher slaving accuracy, a frequency detector is used to compare the outputs of the receiver and transmitter oscillators in the second mode, and to control the receiver oscillator into frequency synchronism with the transmitter oscillator.

Fast acquisition clock recovery system

A high speed clock recovery system that provides a precise 90.degree. phase shift at the incoming NRZ data rate by using a series of differential inverters and controlling their delays in accordance with the corresponding delays of differential inverters of a ring oscillator that is part of a phase-locked loop. More particularly, the incoming NRZ data and the phase shifted data are fed to an exclusive OR that provides an output signal including a frequency component of the originating clock of the NRZ data. The phase-locked loop further includes a phase detector which is responsive to the output of the exclusive OR and the ring oscillator. Thus, once the loop locks, the ring oscillator is synchronized to the frequency of the originating clock for the NRZ data. By slaving the differential inverters of the phase shifter and the ring oscillator to the same delays, the phase shifter provides a dynamically adjusted delay of precisely 90.degree. at the originating clock frequency of the incoming NRZ data.

Growing community of inventors

San Bruno, CA, United States of America

Sam H Moy