Surgical generator for ultrasonic and electrosurgical devices

A control circuit to receive a control signal from a surgical generator, the control signal defining a first phase and a second phase, the control circuit comprising:

• a resistor network comprising resistors arranged in parallel to each other;
• a capacitor coupled in series with the resistor network;
• and
• a plurality of switches, each of the switches configured to transition between an open state and a closed state;
• wherein the control circuit is to transition between a plurality of states corresponding to a plurality of operational modes of a surgical instrument;
• wherein, in the first phase of the control signal, the control circuit is to communicate surgical instrument information to the surgical generator;
• wherein, in the second phase of the control signal, the control circuit is to provide an output corresponding to one of the plurality of states of the control circuit;
• wherein the plurality of switches are configured to transition the control circuit between the plurality of states;
• and
• wherein a state of the plurality of switches is determinable based on a slope of a voltage of the capacitor.