Semiconductor device

A semiconductor device having a nonvolatile variable resistor, the device comprising:

• a resistance value conversion circuit unit that is configured to convert a resistance value of the nonvolatile variable resistor into a potential or a current and that outputs the converted potential or current;
• a comparison circuit unit configured to compare the output from the resistance value conversion circuit unit with a potential or a current at some nodes within the semiconductor device;
• a resistance value changing circuit unit that is configured to change the resistance value of the nonvolatile variable resistor based on the comparison results from the comparison circuit unit,
• wherein the semiconductor device is implemented as a phase-locked loop (PLL) device, and wherein the resistance value conversion circuit unit comprises:
• a current source circuit;
• a first transistor having a source directly connected to the current source circuit, a gate invertedly connected to a voltage input, and a drain directly connected to a first end of the nonvolatile variable resistor;
• and
• a second transistor having a source directly connected to a second end of the nonvolatile variable resistor, a gate non-invertedly connected to the voltage input, and a drain directly connected to ground.