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:
Jul. 09, 1991
Filed:
Nov. 17, 1989
Masashi Arai, Oizumi, JP;
Sanyo Electric Co., Ltd., Osaka, JP;
Abstract
A variable gain amplifier includes a first stage amplifying portion and a subsequent stage amplifying portion for amplifying an output from the first stage amplifying portion and outputting an amplified signal to an output terminal. The first stage amplifying portion includes first and second transistors having emitters connected to each other through a resistor based upon which an input dynamic range is determined, and first and second diodes which are connected to collectors of the transistors as loads thereof. A reference current is generated by a reference current generating portion. A control current generating portion generates a control current which is N times the reference current and supplied to the collectors of the first and second transistors. Currents flowing through the first and second diodes is sunk by a current sinking portion. Values of the above reference current and a sunk current by the current sinking portion is controlled by a control portion in accordance with a level of a control signal, whereby a total gain of the variable amplifier can be varied.