CLOCK RECOVERY UNIT

摘要

The clock restoration device in an ATM (Asynchronous Transfer Mode) network includes: a buffering means 1 for asynchronously writing by a write clock WCLK and receiving a read clock RCLK as the result to read out user's information in succession; a buffer controlling means 24 for continuously monitoring a state of the buffering means 1 and adjusting a count value such that a received service clock be kept between the upper and lower thresholds; a clock generating means 21; a first counting and comparing means 22 for inputting the output of the clock generating means 21 to generate a predetermined value; a second counting and comparing means 25 for inputting the output of the buffer controlling means 24 to generate a variable virtual time stamp TS at the transmitter; a triggering means 23 for triggering the clock output of the clock generating means 21 and outputting a service reference clock; and a DPLL means 3 for fixing the phase of the service reference clock output from the triggering means 23 and feeding it back to use it as a read clock of the buffering means 1.