Low dark current logarithmic pixels

The sensitivity of logarithmic pixels at low light levels is limited by the dark current that flows through the load transistor in the pixel in parallel with the photocurrent. A new layout for a logarithmic pixel is reported that significantly reduces the dark current in the pixel. In addition a simple change to the bias voltages applied to the pixel means that the new layout can simultaneously exhibit a linear response to low-light levels and a logarithmic response at higher light levels.