Accurate bias tracking for process variation and supply modulation

A current mirror comprising:

• a bias branch including:
• first and second transistors configured in series between a voltage source and a ground;
• a voltage divider coupled between the voltage source and the ground;
• and
• an op-amp configured to receive as input a divided voltage of the voltage divider and a voltage of a node between the first and second transistors, and drive a gate of the second transistor to pull the node to the divided voltage;
• a power amplifier core coupled to the bias branch including third and fourth transistors configured in series between the voltage source and the ground, wherein:
• the first and third transistors are complementary to the second and fourth transistors;
• a gate of the first transistor and a gate of the third transistor are coupled, and
• the gate of the second transistor and a gate of the fourth transistor are coupled.

A current mirror comprising:

• a bias branch including:
• first and second transistors configured in series between a voltage source and a ground;
• and
• a voltage divider coupled between the voltage source and the ground;
• and
• an op-amp configured to receive as input a divided voltage of the voltage divider and a voltage of a node between the first and second transistors, and drive a gate of the second transistor to pull the node to the divided voltage;
• a power amplifier core coupled to the bias branch including:
• third and fourth transistors configured in series between the voltage source and the ground, wherein:
• a gate of the first transistor and a gate of the third transistor are coupled, and
• the gate of the second transistor and a gate of the fourth transistor are coupled;
• and
• a first inductor that is coupled between the third transistor and the voltage source.