Patent ID: 8089308

Claim:
A phase controlling apparatus comprising: a first delay line with delay units adding a delay amount to a phase of a signal, the first delay line over which, when an input of an input signal is accepted, a delay amount is added by each of the delay units to a phase of the input signal and a delay signal for each input signal of the delay units is output; and a DLL circuit including a second delay line with delay units, the second delay line over which, when an input of an external signal that can be externally switched to a signal different in frequency, a delay amount is added by each of the delay units to a phase of the external signal the external signal being a different signal from the input signal; a phase comparator that compares a phase of a delay signal delayed by all of the delay units of the second delay line and a phase of the external signal to which no delay amount is added on the second delay line to output a phase difference; and a delay-unit controlling circuit that inputs, to each of the delay units of the first delay line and the delay units of the second delay line, a control voltage value that is a value for synchronizing the delay signal to be compared by the phase comparator with the external signal and is generated from the phase difference output from the phase comparator.