Method for Measuring Capacitances of Capacitors

A capacitor measurement circuit for measuring a capacitance of a test capacitor, the capacitor measurement circuit comprising:

• a power supply voltage node;
• a current-measuring device coupled to the power supply voltage node;
• a first PMOS transistor comprising a source coupled to the current-measuring device, and a drain coupled to a first capacitor plate of the test capacitor;
• a first NMOS transistor comprising a source coupled to a ground, and a drain coupled to the first capacitor plate of the test capacitor;
• a second PMOS transistor comprising a source coupled to the current-measuring device, and a drain coupled to a second capacitor plate of the test capacitor;
• and
• a second NMOS transistor comprising a source coupled to the ground, and a drain coupled to the second capacitor plate of the test capacitor.

A method of measuring a capacitance of a test capacitor, the method comprising:

• performing a first charging on the test capacitor, wherein a first parasitic capacitor coupled to the test capacitor is charged along with the test capacitor, and a second parasitic capacitor coupled to the test capacitor is not charged along with the test capacitor, and wherein the first and the second parasitic capacitors are coupled to opposite capacitor plates of the test capacitor;
• measuring a first average current for the first charging;
• performing a second charging on the test capacitor, wherein the second parasitic capacitor is charged along with the test capacitor, and the first parasitic capacitor is not charged along with the test capacitor;
• measuring a second average current for the second charging;
• performing a third charging on the first and the second parasitic capacitors, wherein the test capacitor is not charged along with the first and the second parasitic capacitors;
• measuring a third average current for the third charging;
• and
• calculating the capacitance of the test capacitor from the first, the second, and the third average currents.