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:
Apr. 15, 2003
Filed:
Jul. 27, 2000
Huy Le, San Jose, CA (US);
Thomas Edward Kopley, Menlo Park, CA (US);
Agilent Technologies, Inc., Palo Alto, CA (US);
Abstract
A control circuit for a ring oscillator uses an integrator and a comparator. The integrator receives a square wave signal as an input and provides a triangular wave signal as an output. The comparator generates a second square wave signal by comparing the triangular wave signal and a reference voltage. Duty cycle for the ring oscillator can be modulated by varying the reference voltage. For one embodiment of the control circuit, signal frequency of the ring oscillator can be modulated by varying biasing current for the comparator to set slew rate of the comparator. For one embodiment of the control circuit, a resistor and a capacitor form a simple RC circuit for the integrator. For an alternative embodiment of the control circuit, a resistor and an amplifier with a capacitor in a negative feedback loop form an active RC circuit for the integrator. For one embodiment of the control circuit, the comparator is an inverting comparator. A ring oscillator employing the control circuit can be formed using a plurality of inverters coupled in series with the control circuit. A test system can be formed by coupling an output buffer and the ring oscillator to a device-under-test and monitoring the ring oscillator frequency and device characteristics.