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:
Mar. 18, 2008
Filed:
Mar. 04, 2003
John H. Cafarella, Swampscott, MA (US);
John H. Cafarella, Swampscott, MA (US);
Other;
Abstract
Transceivers using direct conversion between baseband and RF have become popular for low-cost designs. Bandwidth-efficient modulations employ information on both phases of the carrier, and for high-order signaling alphabets, it becomes problematic to realize Direct-Conversion transceivers for which adequate gain balance between I and Q channels throughout the transmit and receive chains. For heterodyne transceivers I-Q balance is often less of an issue, by contrast, because most of the required gain operates at an Intermediate Frequency. In both cases, the trend toward lower supply voltages further exacerbates this problem because of the poorer control of analog parameters at low voltage. The present invention addresses this difficulty via a calibration method and system in which a calibration signal is generated in the transmit stage and injected into the receive stage so that any mismatches in gain can be observed and corrected.