Abstract: A biopsy driver includes a housing, a battery supply, a motor, a trigger, and a control circuit. The control circuit has a trigger switch circuit, a resistance network circuit, and a pulse width modulation circuit. The trigger switch circuit has an OFF state and an ON state. The resistance network circuit is coupled to an input of the pulse width modulation circuit. The pulse width modulation circuit is configured to generate a variable pulse width signal to control a rotational speed of the motor. When the trigger switch circuit is in the ON state, the trigger switch circuit is configured to: connect a negative terminal of the battery supply to the chassis ground, and select a resistance value from the resistance network circuit to select a desired duty cycle of the variable pulse width signal generated by the pulse width modulation circuit.