Multi-channel uv detection for improved solar spectrum and uv index estimation

Patent metadata

Field	Value
Publication number	US-2016131525-A1
Application number	US-201514671063-A
Country	US
Kind code	A1
Filing date	Mar 27, 2015
Priority date	Nov 6, 2014
Publication date	May 12, 2016
Grant date	—

Abstract

The present disclosure describes an ultraviolet (UV) sensor configured to detect a target UV spectrum (e.g., UVB spectrum). The UV sensor includes a first photodiode with a first UV spectral response and a second photodiode with a second UV spectral response. A filter layer having a graded spectral response is formed over the second photodiode, and the second UV spectral response is affected by a controlled parameter (e.g., thickness) of the filter layer. The UV sensor further includes a subtraction circuit coupled with the first photodiode and the second photodiode. The subtraction circuit is configured to provide a differential response based on a difference between the first UV spectral response and the second UV spectral response. The controlled parameter of the filter layer can be selected such that the differential response provides a detected spectral response of the target spectrum.

First claim

What is claimed is:

1 . An ultraviolet (UV) sensor, comprising:
a first photodiode with a first UV spectral response; a second photodiode with a second UV spectral response; a filter layer having a graded spectral response, the filter layer being formed over the second photodiode, wherein the second UV spectral response is affected by a controlled parameter of the filter layer; and a subtraction circuit coupled with the first photodiode and the second photodiode, the subtraction circuit being configured to provide a differential response based on a difference between the first UV spectral response and the second UV spectral response.

2 . The UV sensor of claim 1 , wherein the differential response is associated with a target spectrum, and the controlled parameter is selected to achieve the target spectrum.

3 . The UV sensor of claim 2 , wherein target spectrum comprises a UVB spectrum.

4 . The UV sensor of claim 1 , further comprising a UVA filter formed over the first and second photodiodes.

5 . The UV sensor of claim 1 , wherein the subtraction circuit comprises one or more analog-to-digital converters coupled to the first and second photodiodes followed by a binary subtractor, or a differential amplifier coupled to the first and second photodiodes.

6 . The UV sensor of claim 1 , wherein the filter layer comprises a layer with spectrally graded material absorption.

7 . The UV sensor of claim 6 , wherein the second UV spectral response is affected by a thickness of the layer.

8 . The UV sensor of claim 6 , wherein the filter layer comprises a passivation layer.

9 . The UV sensor of claim 7 , wherein the passivation layer comprises silicon nitride.

10 . A multi-channel ultraviolet (UV) sensor, comprising:
a first photodiode with a first UV spectral response; a second photodiode with a second UV spectral response; a filter layer having a graded spectral response, the filter layer being formed over the second photodiode, wherein the second UV spectral response is affected by a controlled parameter of the filter layer; a first subtraction circuit coupled with the first photodiode and the second photodiode, the first subtraction circuit being configured to provide a first differential response based on a difference between the first UV spectral response and the second UV spectral response; a third photodiode with a third UV spectral response; a metal layer formed over the third photodiode for leakage current cancellation; and a second subtraction circuit coupled with the first photodiode and the third photodiode, the second subtraction circuit being configured to provide a second differential response based on a difference between the first UV spectral response and the third UV spectral response.

11 . The multi-channel UV sensor of claim 10 , wherein the first differential response is associated with a target spectrum, and the controlled parameter is selected to achieve the target spectrum.

12 . The multi-channel UV sensor of claim 10 , further comprising a UVA filter formed over the first and second photodiodes.

13 . The multi-channel UV sensor of claim 10 , wherein the filter layer comprises a layer with spectrally graded material absorption.

14 . The multi-channel UV sensor of claim 13 , wherein the filter layer comprises a passivation layer.

15 . A multi-channel ultraviolet (UV) sensor, comprising:
a first photodiode with a first UV spectral response; a second photodiode with a second UV spectral response; a filter layer having a graded spectral response, the filter layer being formed over the second photodiode, wherein the second UV spectral response is affected by a controlled parameter of the filter layer; a first subtraction circuit coupled with the first photodiode and the second photodiode, the first subtraction circuit being configured to provide a first differential response based on a difference between the first UV spectral response and the second UV spectral response; a third photodiode with a third UV spectral response; a fourth photodiode with a fourth UV spectral response; a metal layer formed over the fourth photodiode for leakage current cancellation; and a second subtraction circuit coupled with the third photodiode and the fourth photodiode, the second subtraction circuit being configured to provide a second differential response based on a difference between the third UV spectral response and the fourth UV spectral response.

16 . The multi-channel UV sensor of claim 15 , wherein the first differential response is associated with a first target spectrum, and the controlled parameter is selected to achieve the target spectrum.

17 . The multi-channel UV sensor of claim 15 , further comprising:
a UVB filter formed over the first and second photodiodes; and a UVA filter formed over the third and fourth photodiodes.

18 . The multi-channel UV sensor of claim 15 , wherein the filter layer comprises a layer with spectrally graded material absorption.

19 . The multi-channel UV sensor of claim 18 , wherein the second UV spectral response is affected by a thickness of the layer.

20 . The multi-channel UV sensor of claim 18 , wherein the filter layer comprises a passivation layer.

Assignees

• Maxim Integrated Products

Inventors

• Edwards Christopher F
• Allen Dan G
• Pei Cheng-Wei
• Mcguire Timothy K
• Jones Joy T
• Kerness Nicole D

Classifications

• G01J1/4228

  arrangements with two or more detectors, e.g. for sensitivity compensation · CPC title

• G01J1/429

  applied to measurement of ultraviolet light (using counting tubes G01T) · CPC title

• G01J1/0488

  with spectral filtering · CPC title

• G01J2001/4266

  for measuring solar light · CPC title

• G01J3/36

  Investigating two or more bands of a spectrum by separate detectors · CPC title