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. 26, 1998
Filed:
Dec. 23, 1996
Franklin M Murden, Greensboro, NC (US);
Carl W Moreland, Greensboro, NC (US);
Analog Devices, Inc., Norwood, MA (US);
Abstract
A digitally controlled programmable attenuator maintains tight phase matching between attenuated signals over wide ranges of frequencies and power levels regardless of the selected attenuation level. This is achieved with a multi-tap ladder network that sets a desired tap-to-tap dB step-size, a plurality of unity gain digitally switched voltage-to-voltage buffers that are connected between the respective taps and a common output, and a fixed gain stage that sets the attenuator's overall gain/attenuation. The buffers maintain a high and substantially constant impedance whether turned on or turned off. Phase matching within 0.2.degree. at frequencies up to 300 MHz for 30 dB of gain variation has been realized. The buffers can be implemented with complementary bipolar or BiCMOS processes