Oscilloscope simulation front end impedance conversion circuit having program control correction function

Abstract

The invention discloses an oscilloscope simulation front end impedance conversion circuit having a program control correction function. A program control current source to a negative power supply at a high frequency crystal triode emitter electrode; under the condition that DC gain is unchanged, the current of the current source is regulated through the program control so as to regulate emitter current of a high frequency crystal triode of the output stage in a impedance conversion circuit, so that the AC gain of the impedance conversion circuit is consistent with the DC gain. Before the product leaves the factory, the current of the program control current source is regulated, which enables the AC gain of the impedance conversion circuit is identical to the DC gain. Artificial manual regulation of a biasing resistor is not needed, and dismantling the machine is not necessary, which is easy to debug. Besides, when an input static resistor of the back stage program control grain variable circuit is changed, dynamic adjustment can be performed, which overcomes the problem that the prior art is not suitable for the occasion of the dynamic change of the backward stage load RL.

Description

technical field [0001] The invention belongs to the technical field of analog signal conditioning in high-speed data acquisition, and more specifically relates to an oscilloscope analog front-end impedance conversion circuit with a program-controlled calibration function, which can calibrate the low-frequency square wave distortion of the circuit through a software program, thereby realizing DC Consistency correction for gain and AC gain. Background technique [0002] The analog signal conditioning front-end circuit is an indispensable and important part of many data acquisition systems. It is used to realize functions such as signal amplification or attenuation, impedance transformation, and bias adjustment, so as to realize accurate quantitative measurement of the measured signal. In a digital oscilloscope, a general-purpose electronic test instrument, it is necessary to test various complex broadband signals, so its frequency response covers DC signals and high-frequency ...

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Problems solved by technology

[0025] 1. It is necessary to manually adjust the adjustable resistance R 5 , once it is found that it is not corrected, it is necessary to disassemble the machine and recalibrate the hardware, which will bring inconvenience to production debugging;

[0026] 2. The circuit requires the post-stage load R L stable, if the post-stage load R L Unstable, it will affect the quiescent collector current of the transistor in the impedance transformation circuit, thereby affecting the AC gain, which destroys the consistency of the DC gain and the AC gain, and the adjustable resistor R has to be readjusted 5 , so, the traditional adjustment adjustable resistor R 5 approach, not suitable for post-stage load R L occasions of dynamic change

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