Experimental Determination of the 3dB Frequency of the Spatially Modulated Light CMOS Detector as a Function of Technology

The Spatially Modulated Light CMOS detector (SML CMOS detector) has taken away the conventional speed limit linked with photodetectors implemented in standard CMOS technology [1-3]. High-speed light detectors can be integrated with the CMOS receiver circuitry on the same silicon wafer without the usage of hybrid technology nor additional process steps. This indicates that the SML-detector will be the solution of choice for cheap, CMOS-compatible receivers in integrated opto-electronic systems. In this work, we measured for the first time a complete set of SML CMOS detectors with varying detector finger width. For each of these detectors, the responsitivity is determined as function of the frequency and the 3dB frequency is extracted from the experimental data. The 3dB frequency of the SML detectors is plotted as a function of detector finger Pitch. It shows a quadratic dependence. This work verifies the predicted maximum frequency of the detector and is therefore important for future SML CMOS detector system development. Keywords—CMOS analog integrated circuits; optical receivers; photodetectors; device modeling.