Abstract: A circuit comprising a semiconductor photodiode with a first and a second terminal and an internal series resistor, including an amplifier with a first input, a second input and an output, the first photodiode terminal being connected to the first amplifier input, the second photodiode terminal being connected to the second amplifier input and a negative feedback being inserted between the output of the amplifier and its first input, characterized in that a coupling is introduced between the output and the second input of the amplifier, by means of which a voltage is generated between the second input of the amplifier and the second terminal of the photodiode, this voltage being oppositely equal to the product of the internal series resistance and the signal current flowing through the resistor.

Abstract: In a Darlington circuit with integrated speed-up diode the parasitic four-layer effect (p-n-p-n), which is detrimental to the circuit, is removed by giving the diode a divided configuration. The width of the sub-regions is chosen to be so small that the short-circuited p-n junction between the cathode of the diode and the base of the control transistor cannot or substantially can not be biased in the forward direction in the inner part of the semiconductor device.