DEVELOPMENT AND INVESTIGATION OF INPUT AMPLIFIER FOR THE OSCILOSCOPE

Digital oscilloscope’s structure has analog signal acquisition circuit, which transforms signal’s amplitude to fit ADC dynamic range. This circuit is commonly called oscilloscope’s vertical or front-end amplifier. Difficulty in designing front-end amplifiers in GHz range largely affects higher frequency range oscilloscope’s price. This work is focused on designing a front-end amplifier using discrete and openly sold components. We propose a design for attenuator, buffer, variable gain circuits. Amplifier’s prototype is designed. Main characteristics of the amplifier were measured. Measured bandwidth is 3 GHz. Amplifier’s gain and attenuation can support vertical scale sensitivity range from 10 mV/div to 1 V/div. Step response distortion is under 10 %. SMD and PTH relay model attenuators were evaluated. In this paper we review oscilloscope’s front-end purpose and structure. We review amplifiers design and provide the results of experimental measurements.