| 摘要 |
<P>PROBLEM TO BE SOLVED: To test data reception when a transmitter and a receiver have a frequency difference by using a loop back test of the same chips using PLL in common. <P>SOLUTION: A negative-feedback loop has a phase comparator 11, a serial-parallel converter 12, a digital filter 13, a control circuit 14, and a phase divider 15. A signal for shifting forcibly a phase to the negative-feedback loop is input from a signal output circuit 17, and counters 18a-18c measure each number of pulses, and a signal processing circuit 16 compares the numbers of pulses, to thereby determine existence of ability for absorbing the phase shift brought by the signal. <P>COPYRIGHT: (C)2005,JPO&NCIPI |
