Active Control of RF Splitter Isolation by Superimposing Bias Current

Takanobu AOYAMA  Yoshiki SHIBATA  Tomohiko KANIE  Takashi TAKEO  

IEICE TRANSACTIONS on Electronics   Vol.E95-C   No.7   pp.1297-1299
Publication Date: 2012/07/01
Online ISSN: 1745-1353
DOI: 10.1587/transele.E95.C.1297
Print ISSN: 0916-8516
Type of Manuscript: BRIEF PAPER
Category: Electronic Circuits
active control,  RF splitter,  isolation,  bias current,  

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The authors propose a new method of controlling the isolation of an RF splitter. In the proposed method, a bias current is superimposed on an RF signal to change the permeability of the ferrite core used in the splitter's transformer. By doing this, the splitter isolation can be controlled. Experimental results have shown that superimposing a bias current of 500 mA improves device isolation by about 5 dB without affecting the loss characteristics.