EP0304560A2
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Photodetector having cascaded photoelements
Assignee: International Business Machines Corp
•
Filing: 1988-05-31
•
Granted: —
•
Expires: 2008-05-31
Abstract
Abstract A photodetection system includes first and second photodetectors (10, 12), each having an anode and a cathode. The anode (10A) of one (10) of the photodetectors is ohmically connected to the cathode (12A) of the other (12) photodetectors. The photodetectors are suitably electrically biased and disposed for receiving one or two light beams. Output circuit means (22) are electrically connected to the anode and cathode junction between the two photodiodes for providing an output electrical signal having low or no common mode noise. A preferred embodiment of the invention using a single semiconductor chip for the entire circuit arrangement is also illustrated.
Inventors
- 👤 Benny Archie Madrid
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-08 15:56
CPC Classifications
G; G11; G11B; G11B11/00; G11B11/10; G11B11/105; G11B7/00; G11B7/12; G11B7/13; H; H03; H03F; H03F3/00; H03F3/04; H03F3/08; H03F3/087
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
125 words
Electrical apparatus for detecting light beams to be intercepted by first and second photodetectors (10,12), each said photodetector having an anode and a cathode; the improvement including, in combination: the anode (lOA) of the first photodetector (10) being electrically ohmically connected to the cathode (12A) of the second photodetector (12); first and second electrical bias means (14, +V₂; 15,-V₁, 26), said electrical bias means respectively supplying relatively positive and negative electrical bias; the cathode of the first photodetector being electrically-ohmically connected to said first electrical bias means; the anode of the first photodetector being electrically-ohmically connected to the said second electrical bias means; and output circuit means having an input electrically connected to anode of the first photodetector and the cathode of the second photodetector.
Claim 2
Dependent Claim
125 words
Electrical apparatus for detecting light beams to be intercepted by first and second photodetectors (10,12), each said photodetector having an anode and a cathode; the improvement including, in combination: the anode (lOA) of the first photodetector (10) being electrically ohmically connected to the cathode (12A) of the second photodetector (12); first and second electrical bias means (14, +V₂; 15,-V₁, 26), said electrical bias means respectively supplying relatively positive and negative electrical bias; the cathode of the first photodetector being electrically-ohmically connected to said first electrical bias means; the anode of the first photodetector being electrically-ohmically connected to the said second electrical bias means; and output circuit means having an input electrically connected to anode of the first photodetector and the cathode of the second photodetector.
Claim 3
Dependent Claim
30 words
The electrical apparatus set forth in claim 1, wherein said output circuit means is a transimpedance amplifier (22) having an input which is the input of the output circuit means.
Claim 4
Dependent Claim
72 words
The electrical apparatus set forth in claim 1, wherein said first and second electrical bias means are individual operational amplifiers, each having an input and an output connection, said input connections of the operational amplifiers being respectively electrically-ohmically connected to the cathode of the first photodetector and the anode of the second photodetector; and both said operational amplifiers supplying output signals respectively representative of light impinging on said first and second photodetectors.
Claim 5
Dependent Claim
33 words
The electrical apparatus set forth in claim 1, further including, a semiconductor chip (30), first and second isolated regions (31, 32) in the chip, said photodetectors being in said second isolated region (32).
Claim 6
Dependent Claim
29 words
The electrical apparatus set forth in claim 1, wherein said first and second isolated regions have a physical separation on the chip of about five thousandths of one inch.
Claim 7
Dependent Claim
65 words
The electrical apparatus set forth in claim 1, wherein said photodetectors both are closely juxtaposed; means for intercepting a small cross-section light meam having intensity modulations carrying information and means for splitting the light beam into two beams and for directing the two light beams to the photodetectors, respectivley; and data detection means electrically coupled to said output circuit means for detecting the carried information.
Claim 8
Dependent Claim
53 words
The electrical apparatus set forth in claim 6, further including, in combination: first and second output amplifiers (25, 26), each having input signal means respectively connected to said cathode of the first photodetector and the anode of the second phhotdetector for supplying output signals indicative of the light impinging on the respective photodetectors.
Claim 9
Dependent Claim
71 words
In a photodetection circuit having low common mode signal, the combination of: first and second identical photodetectors each having an anode means and a cathode means with the anode means of the first photodetector being ohmically coupled to the cathode means of the second photodetector; and output circuit means electrically coupled to said anode means of the first photodetector and an output means carrying a signal with no common mode noise.
Claim 10
Dependent Claim
71 words
In a photodetection circuit having low common mode signal, the combination of: first and second identical photodetectors each having an anode means and a cathode means with the anode means of the first photodetector being ohmically coupled to the cathode means of the second photodetector; and output circuit means electrically coupled to said anode means of the first photodetector and an output means carrying a signal with no common mode noise.
Claim 11
Dependent Claim
50 words
In the photodetection circuit set forth 8, further including, in combination: first and second individual output means respectively-electrically coupled to the cathode means of the first photodetector and the anode means of the second photodetector with the first and second individual output means not having said inherent common mode rejection.
Claim 12
Dependent Claim
50 words
In the photodetection circuit set forth 8, further including, in combination: first and second individual output means respectively-electrically coupled to the cathode means of the first photodetector and the anode means of the second photodetector with the first and second individual output means not having said inherent common mode rejection.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
Maintenance schedule is calculated for granted US utility patents.