Research of relation of samplers frequency characteristics
Abstract
The approach to reduce the amplitude noise of a vertical channel of the sampling oscilloscope is presented in this paper. In general, the vertical channel of the sampling oscilloscope consists of a high-frequency sampling circuit and a relatively low-frequency sample transmission path along with a high bit resolution analogto-digital converter. The paper presents a method to improve the sensitivity of the vertical channel of a stroboscopic oscilloscope by extending the conventional channel architecture. The main vertical channel unit of the oscilloscope is a sampling device (sampler), which made of discrete elements and usually implemented using high frequency diodes. The sampler performs a transformation of the sample of the high-frequency signal under test into a low-frequency equivalent signal (otherwise called a balance impulse). In a conventional sampling device, this pulse is quantized once the amplitude is at its highest, thus achieving the best signal-to-noise ratio. The paper analyzes the operating parameters of the sampling device circuit and their influence on the output signal of the sampler. In this approach uses the fastest (15 MHz) high-resolution (18-bit) analog-to-digital converters currently on the market to reduce the amplitude noise of vertical channel based on conventional architecture. Our research has shown that it is possible to obtain an increase in the signal-tonoise ratio of almost 1.3 times.
Article in Lithuanian.
Stroboskopinio osciloskopo vertikaliojo kanalo triukšmo mažinimo metodas
Santrauka
Straipsnyje yra pateikiamas metodas, leidžiantis pagerinti stroboskopinio osciloskopo vertikaliojo kanalo jautrumą praplečiant įprastą kanalo architektūrą. Pagrindinis osciloskopo vertikaliojo kanalo mazgas yra strobavimo įtaisas (signalų maišytuvas), kuris sistemose, gaminamose iš diskrečiųjų elementų, dažniausiai įgyvendinamas taikant aukštadažnius diodus. Strobavimo įtaise vykdoma tiriamojo aušktadažnio signalo imties transformacija į žemadažnį ekvivalentinį signalą (kitaip vadinamas balanso impulsu). Įprastos architektūros strobavimo įtaise šis impulsas yra kvantuojamas vieną kartą, kai amplitudė esti didžiausia, taip pasiekiamas geriausias signalo ir triukšmo santykis. Straipsnyje yra analizuojami strobavimo įtaiso grandinės darbo parametrai ir jų įtaka įtaiso išėjimo signalui, taikant šiuo metu rinkoje sparčiausius (15 MHz) didelio skiltiškumo (18-bit) analoginius skaitmeninius keitiklius siekiama sumažinti įprastos architektūros vertikaliojo kanalo amplitudės triukšmą.
Reikšminiai žodžiai: stroboskopinis osciloskopas, strobavimo įtaisas, vertikalusis kanalas, analoginis skaitmeninis keitiklis, ekvivalentinio laiko strobavimo metodas.
Keyword : sampling oscilloscope, sampler, vertical channel, analog-to-digital converters, equivalent time sampling, noise reduction method
This work is licensed under a Creative Commons Attribution 4.0 International License.
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