Novel attenuation network

Abstract

The invention discloses a novel attenuation network comprising a first resistor, a second resistor, a first capacitor, a second capacitor and a first module. The A port is connected with the signal input end through the first resistor. The B port is connected with the power ground through the second resistor. The W port is connected with the signal input end. The two ends of the first capacitor are connected with the signal input end and the signal output end. The two ends of the second capacitor are connected with the signal output end and the power ground. A digital potentiometer is embeddedbetween the first resistor and the second resistor, and the constant voltage is provided to the digital potentiometer through a bootstrap boost unit. A two-way isolation isolator is also introduced to act as a driving chip for normally driving the digital potentiometer, and the external control side can conveniently control the digital potentiometer through the isolator so as to adjust the position of the sliding end of the internal adjustable resistor and acquire the better effect than that the prior art. The novel attenuation network also has the advantages of simple structure, low cost andconvenient adjustment.

Description

technical field [0001] The invention relates to the field of oscilloscopes, in particular to a novel attenuation network used in the oscilloscope to attenuate the amplitude of the signal to be measured. Background technique [0002] The internal circuit board of the existing oscilloscope generally uses a passive attenuation network to attenuate the amplitude of the signal to be measured, and its basic principle is the resistance voltage divider method. like figure 1 As shown, since the oscilloscope has a requirement of 1M input impedance, the resistance value of the voltage divider resistors is relatively large. Since the amplifier and PCB will have unavoidable parasitic capacitance, which will seriously affect the bandwidth of the oscilloscope, it is necessary to add a capacitor to compensate its bandwidth. According to its transfer function, it can be obtained that when C1 / (C2+Cadj)=R2 / R1, the poles and zeros cancel each other out, so that the bandwidth is flat. Among th...

AI Technical Summary

Problems solved by technology

At present, the existing adjustable capacitors are all mechanically adjustable, and cannot be adjusted through a program. They must be adjusted manually. If they are manually adjusted, they must be adjusted before installing the shielding shell. However, the shielding shell itself will generate a certain amount of parasitic capacitance, so Even if the adjustment is done before installing the shielding case, after the shielding case is installed, the previous adjustment effect will change due to the addition of parasitic capacitance, which will eventually affect the measurement of the signal by the oscilloscope and reduce its measurement accuracy.

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