Current Sense Circuitry

A power electronics device, comprising:

• a GaN (gallium nitride) die comprising a first current sense terminal, a second current sense terminal, a main GaN power transistor, a GaN current sense transistor having a source electrically connected to a source of the main GaN power transistor, a diode device electrically connected in series between a drain of the main GaN power transistor and a drain of the GaN current sense transistor, a first voltage protection device electrically connecting the drain of the main GaN power transistor to the first sense terminal, and a second voltage protection device electrically connecting the drain of the GaN current sense transistor to the second sense terminal;
• and
• current sense circuitry comprising a current mirror circuit having an input terminal to sense a current at the second current sense terminal of the GaN die and an output terminal to provide a scaled-down version of the sensed current, a capacitor directly connected to the current mirror circuit at a first node, a comparator circuit having a first input electrically connected to the input terminal of the current mirror circuit, a second input electrically connected to the first current sense terminal of the GaN die, and an output that is in a first state when a voltage at the first input is higher than a voltage at the second input and in a second state when the voltage at the first input is lower than the voltage at the second input, a first switched current source configured to source current to the first node if the main GaN power transistor is on and the comparator output is in the second state, and a second switched current source configured to sink current from the first node if the main GaN power transistor is on and the comparator output is in the first state.