System for determining transistor operating characteristics

A system comprising:

• a current source configured to generate a source current;
• a current supply circuit configured to receive the source current and output a supply current in response to receiving the source current;
• a first test transistor configured to pass a first portion of the supply current in response to the current supply circuit outputting the supply current;
• a second test transistor configured to pass a second portion of the supply current in response to the current supply circuit outputting the supply current;
• a measurement circuit configured to measure a current at the current source and measure a voltage across the first test transistor and the second test transistor;
• and
• a ring oscillator circuit configured to output a first oscillating signal to a control terminal of the first test transistor and output a second oscillating signal to a control terminal of the second test transistor, wherein the second oscillating signal is inverted relative to the first oscillating signal.

A method comprising:

• receiving a source current;
• providing a supply current to a first test transistor and a second test transistor in response to receiving the source current;
• generating a first oscillating signal and providing the first oscillating signal to a control terminal of the first test transistor;
• inverting the first oscillating signal, thereby forming a second oscillating signal, and providing the second oscillating signal to a control terminal of the second test transistor;
• measuring a voltage across the first test transistor and the second test transistor;
• measuring the source current;
• and
• determining one or more operating characteristics of the first test transistor and the second test transistor based on the measured voltage across the first test transistor and the second test transistor and based on the measured source current.