A 2-GHz Gain Equalizer for Analog Signal Transmission Using Feedforward Compensation by a Low-Pass Filter

Masayoshi TAKAHASHI  Keiichi YAMAMOTO  Norio CHUJO  Ritsurou ORIHASHI  

IEICE TRANSACTIONS on Fundamentals of Electronics, Communications and Computer Sciences   Vol.E94-A   No.2   pp.611-616
Publication Date: 2011/02/01
Online ISSN: 1745-1337
DOI: 10.1587/transfun.E94.A.611
Print ISSN: 0916-8508
Type of Manuscript: Special Section PAPER (Special Section on Analog Circuit Techniques and Related Topics)
equalizer,  analog signal transmission,  low-pass filter,  

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A 2 GHz gain equalizer for analog signal transmission using a novel gain compensation method is described in this paper. This method is based on feedforward compensation by a low-pass filter, which improves the gain-equalizing performance by subtracting low-pass filtered signals from the directly passed signal at the end of a transmission line. The advantage of the proposed method over the conventional one is that the gain is equalized with a smaller THD at higher frequencies by using a low-pass instead of a high-pass filter. In this circuit, the peak gain is adjustable from 0 to 2.4 dB and the frequency of the peak gain can be controlled up to 2 GHz by varying the value of an external capacitor. Also this circuit achieves THD with 5 dB better than the conventional circuits.