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一、接地在研制和使用小信号采集系统时正确接地是至关重要的,接地不当将会引起严重的测量误差.最差的走线如图1a所示,是电源地接低电平的前置放大的地,再接功率级的地.功率级从电源中得到的大电流都流过前置放大级的地电阻,所产生的地电流干扰被放大,从而造成很大的接地误差.在逻辑线路中脉冲干扰还将使采集系统的模拟-数字转换输出的码子乱跳.因此,设计印制板时如果共地接法不便的话,可以将电源地接功率级的地,再接低电平放大的地,接地线从电源地引到插脚.这样,低电平放大的地线中流过的电流就比较小.
First, the ground In the development and use of small signal acquisition system is properly grounded correctly, improper grounding will cause serious measurement errors. The worst route shown in Figure 1a, is the power to the low before Put ground amplification, then the power level ground.Power level from the power supply to the large current flows through the preamplifier stage of the ground resistance, the resulting ground current interference is amplified, resulting in a large ground error. Pulse interference in the logic circuit will also make the acquisition system analog-digital conversion output code jitter. Therefore, the design of printed circuit board if the total ground inconvenience, then the power ground can be connected to the power level, then low When the ground is flat, ground leads from the power supply to the pins, so that the current flowing through the ground at low level is small.