Delay time controlling circuit and method for controlling delay time

A delay time controlling circuit which controls a delay time the delay time controlling circuit comprising:

• a programmable variable delay circuit;
• a phase detector which compares a phase of a reference signal to a phase of an output signal in response to a first control signal and generates a code control signal (based on the results of the comparison);
• a controller which generates a first code signal which is an m-bit signal (where m is a natural number) in response to the code control signal;
• a fuse unit, having a plurality of fuses, which receives the first code signal, cuts fuses in itself in response to a second control signal if the measured delay time matches a target delay time, and generates a second code signal, which is an m-bit signal (where m is a natural number) and corresponds to the logic value of the fuses that are cut;
• a selection fuse which is cut in response to a third control signal;
• and
• a selector which selects one of the first and second code signals based on whether or not the selection fuse is cut and outputs the selected one as a delay control signal for controlling the delay time of the variable delay circuit.

A method for controlling the delay time of a delay time controlling circuit, the method comprising:

• (a) outputting a first code signal which is an m-bit signal (where m is a natural number) in response to a first control signal;
• (b) controlling and measuring the delay time of the variable delay circuit in response to the first code signal;
• (c) cutting fuses in a fuse unit in response to a second control signal if the measured delay time reaches a target delay time and generating a second code signal which is an m-bit signal (where m is a natural number) and corresponds to the logic value of the fuses that are cut;
• and
• (d) outputting the second code signal as a delay control signal and thus fixing the delay time of the variable delay circuit.

A method for controlling the delay time of a delay time controlling circuit which controls the delay time of a variable delay circuit, the method comprising:

• (a) comparing the phase of a reference signal which is an m-bit signal (where m is a natural number) and the phase of an output signal of the variable delay circuit in response to a first control signal and generating a code control signal based on the results of the comparison;
• (b) generating a first code signal which is an m-bit signal (where m is a natural number) in response to the code control signal;
• (c) controlling and measuring delay time of the variable delay circuit in response to the first code signal;
• (d) cutting fuses in a fuse unit in response to a second control signal if the measured delay time reaches a target delay time and generating a second code signal which is an m-bit signal (where m is a natural number) and corresponds to the logic value of the fuses that are cut;
• and
• (e) outputting the second code signal as a delay control signal and thus fixing the delay time of the variable delay circuit.