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:
Oct. 13, 1998
Filed:
Apr. 18, 1997
Gregory Weng Yuen, Harlow, GB;
Northern Telecom Limited, Montreal, CA;
Abstract
A transformer-coupled mixer circuit including dc voltage supply; and four transistors, arranged as a first transistor pair and a second transistor pair. Each transistor pair has a first transistor and a second transistor and each transistor has a base, a collector and an emitter. The emitter of the first transistor in each transistor pair is connected to the collector of the second transistor in that transistor pair, and the emitter of the second transistor in each transistor pair is connected to a current sink. The circuit also comprises a transformer, having a set of primary windings and first and second sets of secondary windings, the first set of secondary windings being connected in series with the emitter of the first transistor in the first transistor pair and the second set of secondary windings being connected in series with the emitter of the first transistor in the second transistor pair. The windings are arranged such that outputs taken from the first and second sets of secondary windings are 180 degrees out of phase, and the primary windings of the transformer are arranged to receive an input signal. The bases of all of the transistors are arranged to receive local oscillator signals, the dc voltage applied to the second transistor in each transistor pair being less than the dc voltage applied to the first transistor in each transistor pair. Finally, the signals applied to the first transistor pair are the inverse of the signals applied to the second transistor pair, such that the local oscillator signals activate only one transistor pair at a time.