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.

Date of Patent:
Apr. 04, 2017

Filed:

Nov. 24, 2015
Applicant:

Analog Devices, Inc., Norwood, MA (US);

Inventor:

John Cowles, Beaverton, OR (US);

Assignee:

ANALOG DEVICES, INC., Norwood, MA (US);

Attorney:
Primary Examiner:
Int. Cl.
CPC ...
H03B 1/00 (2006.01); H03K 5/00 (2006.01); H04B 1/10 (2006.01); H03H 11/12 (2006.01);
U.S. Cl.
CPC ...
H03H 11/1213 (2013.01); H03H 11/1204 (2013.01); H03H 11/1291 (2013.01);
Abstract

Filter circuits with emitter follower transistors and servo loops, and associated methods and apparatuses, are disclosed herein. In some embodiments, a filter circuit may include: a resistor-capacitor network having an input to receive an input signal; an emitter follower transistor, coupled to the resistor-capacitor network, wherein the filter circuit has an output to provide an output signal from the emitter of the emitter follower transistor; a current source to provide a constant reference current; and a current-buffering servo loop circuit, coupled to the emitter follower transistor and the current source, including a current buffer and a controlled current sink to maintain the collector current and the emitter current of the emitter follower transistor equal to the constant reference current.


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