High gain current mode photo-sensor

Abstract

A high gain photodetector requiring a substantially silicon area than prior art photodetectors having the same gain. The photodetector includes a light converter for converting a light signal to a current; and a first vertical transistor. The first vertical transistor includes a first well in a semiconductor substrate, the first well including a diffusion region, the semiconductor substrate and the diffusion having a first type of doping and the first well having a second type of doping. The first type of doping is either P-type or N-type, and the second type of doping is the other of the P-type or N-type doping. The light converter is connected to the first well so as to forward bias the vertical transistor thereby causing a current to flow between the diffusion region in the first well and the substrate. Additional amplification of the photocurrent from the light converter can be provided by including a second vertical transistor. The second vertical transistor includes a second well in the semiconductor substrate, the second well including a second diffusion region. The semiconductor substrate and the second diffusion having the first type of doping and the second well having the second type of doping. The first vertical transistor and the second vertical transistor are connected as a Darlington pair. The amplified current from the vertical transistor(s) is converted to a voltage by a current to voltage converter.

Dependencies are inferred from the claim text.