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:
May. 15, 2001
Filed:
Feb. 09, 2000
Zhiliang Zheng, San Jose, CA (US);
Marvell International Ltd., , BM;
Abstract
In this invention an integrated operational amplifier is calibrated to optimize phase margin. The calibration is done to correct changes caused by operating temp and supply voltages as well as process variations and aging that can affect the stability of the amplifier. A calibration circuit measures the response of the operational amplifier to a pulse input and controls a feedback impedance to produce an optimized phase margin. The output response to the pulse input is measured at two different times, at a first time close to the transition capturing the peak overshoot from an under damped amplifier and at second time later than the first measurement when the distortions from the under damped ringing have diminished. A quantizer circuit compares the two measure voltages and provides an input to control logic which selects the amount of reactance in the feedback of the operational amplifier. The calibration terminates when the dampening of the amplifier has reached the least significant bit of adjustment available to the calibration process.