J. Daniel Smisko
Electrician in Newark, DE
License number
Delaware TH-0001175
Issued Date
Oct 25, 2004
Expiration Date
Oct 25, 2005
Category
Electrical Examiners
Type
Homeowner's Permit
Address
Address
2
Newark, DE 19711
Professional information
Noise Reduction For Photodiode Arrays
US Patent:
4902886, Feb 20, 1990
Filed:
Jan 23, 1989
Appl. No.:
7/299382
Inventors:
J. Daniel Smisko - Newark DE
Assignee:
Hewlett-Packard Company - Palo Alto CA
International Classification:
H01J 4014
US Classification:
250214R
Abstract:
A method and apparatus for reducing noise in a light sensing circuit having a photodiode array coupled to a charge amplifier through a field effect transistor transfer switch. Thermal noise generated by the transfer switch is combined with image signals inputted to the charge amplifier resulting in an outputted noisy image signal. The invention eliminates this noise by taking two consecutive readings of the charge amplifier output, one before and one after closing the transfer switch and after opening it. The thermal noise generated by the transfer switch, and added to the next reading of the charge amplifier output, is equal to the difference between these two readings. Once stored, this difference can be subtracted from the previously mentioned "next reading", resulting in the elimination of this noise term.