A double quench circuit (100, 100a, 100') for an avalanche current device, the circuit comprising: an avalanche current device (12c, 12d, 12e) having a first terminal responsive to a bias voltage to reverse bias the avalanche current device above its avalanche breakdown voltage; a first quench circuit (104, 104d, 104e) responsive to the bias voltage and coupled to the first terminal of the avalanche current device for reducing the amount of the avalanche current passing through the avalanche current device; and a second quench circuit (106, 106d, 106e) coupled to a second terminal of the avalanche current device for providing a quenching voltage to the second terminal to counteract and reduce the amount of the avalanche current passing through the avalanche current device; the double quench circuit being characterised by: a detection circuit (114, 114e) responsive to avalanche current of the avalanche current device for detecting the avalanche current and generating an output signal in response thereto; the second quench circuit including an active quench circuit responsive to the output signal of the detection circuit for raising the voltage of the second terminal of the avalanche current device to reduce the avalanche current of the avalanche current device; and a first active reset circuit (110, 110e) responsive to the output signal of the detection circuit, said active reset circuit configured to connect the first terminal to the bias voltage to recharge the avalanche current device above its avalanche breakdown voltage to reset the avalanche current device. an avalanche current device (12c, 12d, 12e) having a first terminal responsive to a bias voltage to reverse bias the avalanche current device above its avalanche breakdown voltage; a first quench circuit (104, 104d, 104e) responsive to the bias voltage and coupled to the first terminal of the avalanche current device for reducing the amount of the avalanche current passing through the avalanche current device; and a second quench circuit (106, 106d, 106e) coupled to a second terminal of the avalanche current device for providing a quenching voltage to the second terminal to counteract and reduce the amount of the avalanche current passing through the avalanche current device; the double quench circuit being characterised by: a detection circuit (114, 114e) responsive to avalanche current of the avalanche current device for detecting the avalanche current and generating an output signal in response thereto; the second quench circuit including an active quench circuit responsive to the output signal of the detection circuit for raising the voltage of the second terminal of the avalanche current device to reduce the avalanche current of the avalanche current device; and a first active reset circuit (110, 110e) responsive to the output signal of the detection circuit, said active reset circuit configured to connect the first terminal to the bias voltage to recharge the avalanche current device above its avalanche breakdown voltage to reset the avalanche current device. a detection circuit (114, 114e) responsive to avalanche current of the avalanche current device for detecting the avalanche current and generating an output signal in response thereto; the second quench circuit including an active quench circuit responsive to the output signal of the detection circuit for raising the voltage of the second terminal of the avalanche current device to reduce the avalanche current of the avalanche current device; and a first active reset circuit (110, 110e) responsive to the output signal of the detection circuit, said active reset circuit configured to connect the first terminal to the bias voltage to recharge the avalanche current device above its avalanche breakdown voltage to reset the avalanche current device.