Ultra-Wideband Low-Noise Amplifier

Ultra-Wideband (UWB) Low-Noise Amplifier (LNA) is an essential part of the digital TV and UWB signal processor, but what makes it hard to design is the comprehensive consideration of bandwidth, noise and gain control performance. A new solution of high performance amplifier with low-noise, UWB and direct current (DC) is presented (Fig. 1), which is composed of a precision pre-amplifier with AD797, a stepped gain controller with VCA810 and a digital potentiometer, an eight-order Bessel low-pass filter with LC network, a zero-drift corrector with the digital compensation method. The test results (Tab 1-3 & Fig. 6) show that the gain of amplifier can be adjusted from 0 to 80dB by step, the fluctuation of the pass band from DC to 10MHz is less than 0.87dB, stop-band attenuation reaches -42dB/2f(c), the equivalent input noise voltage is less than 7.2 mu V-rms. This design successfully solves some high challenging contradictions, such as ultra-wideband and low-noise, stop-band attenuation and pass-band fluctuation, precise gain control and DC zero-drift correction. (C) 2012 Published by Elsevier B.V. Selection and/or peer-review under responsibility of Garry Lee