A circuit and device including a transistor and diode

A method of operating a circuit;

• the circuit comprising a bipolar transistor, a diode having a first terminal connected to a base terminal of the bipolar transistor;
• and a second terminal of the diode connected to a reference voltage;
• a voltage being applied across and emitter terminal of the bipolar transistor and the second terminal of the diode;
• the method comprising switchably connecting the base terminal of the bipolar transistor and the first terminal of the diode to a signal source having an impedance lower than an impendence across an emitter terminal and a base terminal of the bipolar transistor such that:
• when not connected, so as to cause a current flow through the base terminal of the bipolar transistor and through the diode to, turn the bipolar transistor ON;
• and
• when connected current flow through a control terminal of the bipolar transistor reduces to switch the bipolar transistor OFF.

A semiconductor device comprising:

• a bipolar transistor comprises:
• first and second regions of a first type of semiconductor material that provide collector and emitter regions of the bipolar transistor, and a first region of a second type of semiconductor material that provides a base region of the bipolar transistor, interposed between and in contact with each of the first and second regions of the first type of semiconductor material;
• and
• a diode comprises:
• the first region of the second type of semiconductor material;
• and
• a further region of the first type of semiconductor material in contact with a highly doped portion of the first region of the second type of semiconductor material to form a diode junction.