The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Aug. 17, 1993
Filed:
Oct. 08, 1991
Urs T Durig, Ruschlikon, CH;
Bruno Michel, Gattikon, CH;
International Business Machines Corporation, Armonk, NY (US);
Abstract
The design of a current-to-voltage converter with a uniform transfer function in its feedback loop (12) is proposed. It employs a very large, double-shielded measuring resistance (13) and a two-stage setup to perform a fully linear I/V conversion with a conversion factor of 10.sup.10 V/A and a bandwidth of 1 MHz. With the low noise level attained, and with the bandwidth and conversion factor mentioned, it will be possible to monitor events involving as few as 300 electrons. The current-to-voltage converter comprises a differential input amplifier (8), a current source (11) for supplying said differential amplifier (8), at least one operational amplifier (10, 14), and a high-valued measuring resistance (13) the voltage drop across which is being taken as a measure of the current to be detected. The measuring resistance (13) is arranged in a feedback loop (12) associated with said differential amplifier (8). The measuring resistance (13) is double-shielded from the remainder of the current/voltage converter circuitry through its arrangement inside a cylindrical capacitor C which acts as a first shield, and which is in turn connected to a casing (15, 25) surrounding the differential amplifier (8) and the feedback loop (12) and which constitutes a second shield.