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:
Sep. 12, 2000
Filed:
Oct. 06, 1997
Uttam S Ghoshal, Austin, TX (US);
Snigdha Ghoshal, Austin, TX (US);
Other;
Abstract
A system for measuring magnetic fields produced by an integrated circuit device-under-test includes a clock generator configured to generate a clock signal, a delay circuit configured to generate a delayed clock signal having a known delay relative to the clock signal, a pulse generator configured to generate a series of pulses having a frequency corresponding to a frequency of the clock signal, the pulses of the series of pulses being offset from the clock signal by the known delay, and a sensor having a property that varies in response to a magnetic field at the sensor. A sampling circuit connected to the sensor and to the pulse generator is configured to measure the property of the sensor at times corresponding to pulses of the series of pulses, and to produce a sampling signal having, for each pulse, a first value (e.g., a logical one) when the property of the sensor indicates that the magnetic field at the sensor exceeds a threshold amount and a second value (e.g., a logical zero) when the property of the sensor indicates that the magnetic field at the sensor does not exceed the threshold amount. A digital filter is connected to the sampling circuit and configured to produce a first indicator when a number of first values in the sampling signal exceeds a predetermined amount and to produce a second indicator when a number of first values in the sampling signal does not exceed a predetermined amount. A counter connected to the digital filter is configured to increment an output signal in response to one of the first and second indicators and to decrement the output signal in response the other of the first and second indicators. A feedback loop including a digital-to-analog converter is connected to the counter and configured to produce an electrical signal proportional to the output signal, the electrical signal causing the feedback loop to produce a feedback magnetic field in proportion to the output signal, the feedback magnetic field being a component of the magnetic field at the sensor. The output signal of the counter corresponds to a magnetic field produced by the device-under-test.