Kenneth J Kantor

US Patent:

61694088, Jan 2, 2001

Filed:

Sep 30, 1996

Appl. No.:

8/723033

Inventors:

Kenneth J. Kantor - Cedar Park TX
Kent B. Erington - Austin TX
John E. Asquith - Austin TX

Assignee:

Motorola, Inc. - Schaumburg IL

International Classification:

G01R 1900

US Classification:

324752

Abstract:

Amplitude modulated optical beam induced current (AMOBIC) created by irradiating an internal PN junction of an integrated circuit (IC) (20) is used to determine a voltage level of the internal PN junction. In one embodiment, an IC (20) requiring high current and operating above the kilo-Hertz frequency range is monitored using a pulsed infrared laser beam (42). An AMOBIC signal is created when an internal PN junction is irradiated with the pulsed infrared laser beam (42). By using a pulsed infrared laser beam (42) an OBIC signal is amplitude modulated (AM) to a carrier frequency. This carrier frequency is selected so that the AMOBIC signal is large when compared to the various noise sources present at or near the carrier frequency. The noise rejection resulting from frequency shifting of the OBIC perturbation is further increased by selectively attenuating transient current spikes occurring at IC clock edges, whereby IC testing is further improved.