Analysis of the Effect of Analog Switches on the Digital Signal Oscilloscope Circuit

Digital oscilloscopes sold in the market usually have limited functions. For other measurement purposes such as electrical properties, there is still a need to use additional equipment such as impedance analyzers and vector network analyzers. We designed a digital signal oscilloscope for special purposes, which can be used to measure, record, and display signals, as well as measure electrical properties such as inductance, capacitance, resistance, and impedance. Inside the digital signal oscilloscope, there is a switch circuit network that has the function of forwarding the input signal to the signal conditioning circuit. This network switch has stray capacitance and resistance that can affect signal measurements. This paper explains the effect of the network switch on signal measurement. The method used is to create an equivalent circuit model and create a mathematical model, then simulate them using MATLAB or Python. The simulation results show that the switch in the off state still produces a current of about 0.015A which indicates that there is still impedance even though the switch is off.