A variable gain amplifier using a very-high speed OTA

✍ Scribed by You Zheng; Carlos E. Saavedra

• Publisher: John Wiley and Sons
• Year: 2010
• Tongue: English
• Weight: 370 KB
• Volume: 52
• Category: Article
• ISSN: 0895-2477
• DOI: 10.1002/mop.25114

✦ Synopsis

Abstract

A variable gain amplifier is demonstrated using only one fully‐differential operational transconductance amplifier (OTA) as the core circuit element.Gain control is achieved by varying the transconductance of the OTA and by using an output buffer circuit to sum the output signals of the OTA in the correct phase relationship. The circuit was designed and fabricated using 0.18 μm CMOS technology. Measured results show a gain control range of 15 dB between 1 GHz and 3 GHz and the input and output reflection coefficients are below −10 dB and −20 dB, respectively. The output power of the amplifier is +2.3 dBm at its 1‐dB compression point. The chip has a maximum DC power consumption 12.6 mW and it measures 0.25 mm^2^ including bonding pads. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 1112–1116, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.25114