Abstract: The present invention provides a multi-cavity Fabry-Perot ambient light filter apparatus. The multi-cavity Fabry-Perot ambient light filter apparatus comprises a plurality of Fabry-Perot cavities, each of the plurality of Fabry-Perot cavities covering one of a plurality of photodiodes; wherein each of the plurality of Fabry-Perot cavities has two partially reflective layers and one interferometric layer sandwiching between the two partially reflective layers, and shares one of the two partially reflective layers with a neighboring Fabry-Perot cavity and thereby stair stacking with the neighboring Fabry-Perot cavity. The plurality of Fabry-Perot cavities are capable of blocking the ambient light except for a wavelength spectrum that is recognizable for human eyes, thereby effectively accomplishes excellent IR blocking from non-visible light spectra.

Abstract: An anti-reflective coating having a composite layer of silicon nitride and silicon dioxide may be formed over the entire photosensitive region of the photodetector to minimize the amount of reflection. The composite layer comprises a silicon nitride layer and a dielectric layer contiguous to the silicon nitride layer. The anti-reflective coating may be formed in a CMOS process for fabricating the PN junction in the photodiode and CMOS devices for amplifying the photodetector signal, where the polysilicon gate layer is used as a etch stop. The P+ or N+ material in the PN junction of the photodiode has a distributed design where two portions of the region are separated by a distance in the range of Xd to 2Xd, where Xd is the one-sided junction depletion width, to enhance the electric field and to reduce the distance traveled by the carriers for enhancing bandwidth. A heavily doped region of the opposite type may be added between the two portions to further enhance the electric field.

Abstract: A first device comprising a first current mirror is used to amplify the output of a first photodetector. A second device comprising a current mirror arrangement is employed to amplify the output of a second photodetector. The outputs of the two devices are then compared to provide a signal useful for many applications, including that for determining the position of a rotating member or of a member in relative motion to another member. Preferably, no feedback action is used for the amplification of the output of at least one of the photodetectors.

Abstract: An anti-reflective coating having a composite layer of silicon nitride and silicon dioxide may be formed over the entire photosensitive region of the photodetector to minimize the amount of reflection. The composite layer comprises a silicon nitride layer and a dielectric layer contiguous to the silicon nitride layer. The anti-reflective coating may be formed in a CMOS process for fabricating the PN junction in the photodiode and CMOS devices for amplifying the photodetector signal, where the polysilicon gate layer is used as a etch stop. The P+ or N+ material in the PN junction of the photodiode has a distributed design where two portions of the region are separated by a distance in the range of Xd to 2Xd, where Xd is the one-sided junction depletion width, to enhance the electric field and to reduce the distance traveled by the carriers for enhancing bandwidth. A heavily doped region of the opposite type may be added between the two portions to further enhance the electric field.

Abstract: A first device comprising a first current mirror is used to amplify the output of a first photodetector. A second device comprising a current mirror arrangement is employed to amplify the output of a second photodetector. The outputs of the two devices are then compared to provide a signal useful for many applications, including that for determining the position of a rotating member or of a member in relative motion to another member. Preferably, no feedback action is used for the amplification of the output of at least one of the photodetectors.

Abstract: A dual function circuit for providing an output voltage to a transimpedance amplifier is disclosed. The dual function circuit can be selected between functioning as a current to voltage conversion circuit connected to a photodiode and as a testing circuit for testing the transimpedance amplifier without exposing light to the photodiode. The dual function circuit comprises two current mirror pairs to ensure that a substantially similar dc bias current is applied to the two driving transistors. In addition, by applying an input testing voltage to the two driving transistors in a common gate/base design, the output of the testing circuit has wide band frequency response. No switching is required to select between the test mode and the normal mode.

Abstract: An anti-reflective coating having a composite layer of silicon nitride and silicon dioxide may be formed over the entire photosensitive region of the photodetector to minimize the amount of reflection. The composite layer comprises a silicon nitride layer and a dielectric layer contiguous to the silicon nitride layer. The anti-reflective coating may be formed in a CMOS process for fabricating the PN junction in the photodiode and CMOS devices for amplifying the photodetector signal, where the polysilicon gate layer is used as a etch stop. The P+ or N+ material in the PN junction of the photodiode has a distributed design where two portions of the region are separated by a distance in the range of Xd to 2Xd, where Xd is the one-sided junction depletion width, to enhance the electric field and to reduce the distance traveled by the carriers for enhancing bandwidth. A heavily doped region of the opposite type may be added between the two portions to further enhance the electric field.

Abstract: An anti-reflective coating having a composite layer of silicon nitride and silicon dioxide may be formed over the entire photosensitive region of the photodetector to minimize the amount of reflection. The composite layer comprises a silicon nitride layer and a dielectric layer contiguous to the silicon nitride layer. The anti-reflective coating may be formed in a CMOS process for fabricating the PN junction in the photodiode and CMOS devices for amplifying the photodetector signal, where the polysilicon gate layer is used as a etch stop. The P+ or N+ material in the PN junction of the photodiode has a distributed design where two portions of the region are separated by a distance in the range of Xd to 2Xd, where Xd is the one-sided junction depletion width, to enhance the electric field and to reduce the distance traveled by the carriers for enhancing bandwidth. A heavily doped region of the opposite type may be added between the two portions to further enhance the electric field.

Abstract: An anti-reflective coating having a composite layer of silicon nitride and silicon dioxide may be formed over the entire photosensitive region of the photodetector to minimize the amount of reflection. The composite layer comprises a silicon nitride layer and a dielectric layer contiguous to the silicon nitride layer. The anti-reflective coating may be formed in a CMOS process for fabricating the PN junction in the photodiode and CMOS devices for amplifying the photodetector signal, where the polysilicon gate layer is used as a etch stop. The P+ or N+ material in the PN junction of the photodiode has a distributed design where two portions of the region are separated by a distance in the range of Xd to 2Xd, where Xd is the one-sided junction depletion width, to enhance the electric field and to reduce the distance traveled by the carriers for enhancing bandwidth. A heavily doped region of the opposite type may be added between the two portions to further enhance the electric field.

Abstract: The DC level of the output of an amplifier may be dynamically adjusted depending on the operating conditions of the amplifier by comparing the output of the amplifier to a set reference value using a comparator. The output of the comparator is then fed to a state machine which adjusts the DC level of the amplifier output in an autocalibration process until the DC level of the output of the amplifier is substantially equal to the reference value. An undervoltage lockout circuit detects a power supply to the amplifier and causes the calibration to be initiated only when the power supply meets certain requirements. A change in the gain setting in the amplifier is also detected for automatically initiating the calibration process.