Active differential probe with low input capacitance

Abstract

The invention provides an active differential probe with low input capacitance, which comprises two probe input terminals and a differential probe amplification module with double input ends, wherein a damping resistor and an RC (resistor-capacitor) parallel circuit are connected between each probe input terminal and one input end of the differential probe amplification module in series; each RC parallel circuit is formed by connecting an input resistor to an input capacitor in parallel; the input resistors and the input capacitors are arranged on insulation substrates; each input capacitor is arranged at a top layer of each insulation substrate and comprises a first input capacitor and a second input capacitor that are mounted between a first via hole and a second via hole and connected in series; the input resistors are connected between the first via hole and the second via hole and mounted at positions, opposite to the two input capacitors, on the bottom layers of the insulation substrates. According to the probe, each input capacitor is formed by series connection of the two capacitors, so that the lower input capacitance is realized, and the consistency of the two input capacitors of the probe is ensured.

Description

Technical field [0001] The present invention relates to the technical field of measurement and testing, in particular to an active differential probe, and more particularly to an active differential probe with small input capacitance. Background technique [0002] In the field of test and measurement, the probe is a device used to connect the circuit under test and the measuring instrument, collect the signal under test and transmit it to the measuring instrument. The probe needs an undistorted detection signal in its frequency band, and does not adversely affect the circuit or signal under test. This requires the probe to have a larger input resistance and a smaller input capacitance. The high input resistance and small input capacitance can draw a small current from the circuit under test and reduce the impact on the circuit under test. The input resistance needs to be more The resistance of the test circuit itself is much larger, and the smaller the input capacitance, the sma...

AI Technical Summary

Problems solved by technology

Since the capacitors C1P and C1N are very small, generally less than 1pF, they are implemented with chip capacitors. Even if the existing high-precision and high-Q capacitors on the market are used, the highest precision A range can only achieve ±0.05pF due to the limitation of the device itself. It is difficult to achieve the consistency of the two input capacitances when the parasitic capacitance is always present

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