Oscilloscope with front end analog circuit

Abstract

The invention relates to a digital oscilloscope with a front end analog circuit. The digital oscilloscope comprises a signal input module, an input attenuation module, a programmable amplifier, a bandwidth limit module, an ADC driver module, an A / D conversion module, a control and processing module and a D / A conversion module which are orderly connected in series, wherein the input attenuation module comprises a resistance-capacitance network having multiple paths, a switching unit and an operational amplifier unit which are orderly connected in series. The switching unit is controlled by thecontrol and processing module to enable one branch in the resistance-capacitance network to be connected with the input end of the operational amplifier unit and the other branches to be grounded. The resistance-capacitance network cooperates with the operational amplifier unit to attenuate the input signals of the oscilloscope. By adopting the resistance-capacitance network having multiple paths, the invention satisfies the high input impedance of the oscilloscope, and realizes the attenuation of the input signals at different ratios, thereby enlarging the dynamic range of the input signals.

Description

technical field [0001] The invention relates to the field of measuring devices for displaying electrical variables in a wave form, in particular to the field of digital oscilloscopes. Background technique [0002] Commonly used digital oscilloscopes generally include analog front-end circuits, ADC sampling circuits, trigger circuits, digital processing circuits and display circuits. Among them, the analog front-end circuit completes a series of functions such as input high impedance, buffering, attenuation and ADC driving of the input signal to be measured. How to achieve multi-proportional attenuation of the input signal while achieving high input impedance has always been a problem that plagues technicians. [0003] In the prior art, refer to figure 1 , the digital oscilloscope 1 includes a signal input module 10, an input resistor 11, an input attenuation module 12, a programmable amplifier 13, a bandwidth limiting module 14, an ADC driver module 15, an A / D conversion m...

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Problems solved by technology

[0008] 1. Since the dynamic range of the input signal is completely determined by the gate of the junction field effect transistor, and because the input high impedance is realized through the grounding of the 1MΩ resistor 11, only one path is connected to the field effect transistor, and multi-ratio attenuation cannot be realized. The above-mentioned Both lead to a small dynamic range of signal input;

[0009] 2. Due to the poor frequency response flatness of the junction field effect tube, and there is no other circuit structure for adjusting the frequency response, the frequency response flatness of the signal is poor

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