Methods and apparatus for tuning a current source and selecting a reference voltage to maintain a transconductance and transition frequencies of transistors of an inverter

A method comprising:

• receiving a first reference voltage at a current source;
• generating, via the current source, an output current in response to the first reference voltage;
• supplying a portion of the output current from the current source to an inverter, wherein the inverter has a transconductance, and wherein the inverter comprises
• a first transistor having a source and a drain, wherein the source of the first transistor is connected to the current source, and wherein the source of the first transistor is configured to receive the portion of the output current, and
• a second transistor having a source, wherein the source of the second transistor is connected to the drain of the first transistor;
• and
• selecting the first reference voltage such that the output current of the current source varies with changes in a temperature of the current source to (i) maintain the transconductance of the inverter at a same value, and (ii) prevent changes in respective transition frequencies of both the first transistor and the second transistor.

A method comprising:

• selecting a first reference voltage;
• receiving the first reference voltage at a current source;
• based on the reference voltage, generating a output current via the current source;
• recording a level of current output from the current source while (i) the current source is at a predetermined temperature, and (ii) the current source is receiving the first reference voltage;
• subsequent to recording the level of current, selecting a second reference voltage, wherein the second reference voltage is different than the first reference voltage;
• supplying the second reference voltage instead of the first reference voltage to the current source;
• and
• tuning a variable resistance of the current source to match (i) the output current of the current source generated while the temperature of the current source is at the predetermined temperature and while the current source is receiving the first reference voltage to (ii) the level of current output from the current source while the temperature of the current source was at the predetermined temperature and while the current source is receiving the second reference voltage.