大信号下X7R MLCC的电学性能分析

Electrical performance of X7R MLCC under large signals

为了在大功率下能更好地应用多层陶瓷电容器(MLCC),需要在大信号下评价MLCC的电学性能。利用伏安法,通过测量待测电容、采样电阻及两者串联后的有效交流电压,获得待测电容和采样电阻的相位差,计算出待测电容的电容及介电损耗,建立了大信号下MLCC数据图谱。结果表明,交流电压不变时,电容随着偏压的增加而增加,交流电压较小时,损耗几乎不随偏压变化而变化;在高直流偏压下,电容和介电损耗随着交流电压的增加而增加;在某些偏压下,电容可大范围内不随交流电压变化而变化;偏压改变时,如果同时改变交流电压,电容也可获得恒定值。一定程度上解决了材料或元器件现有的电学参数与实际应用需求之间的矛盾。

In order to better apply multilayer ceramic capacitors(MLCC)under high power,it is necessary to evaluate the electrical performance of MLCC under large signals.By measuring the capacitance,the sampling resistance and the effective AC voltage after series connection with the voltammetry method,the phase difference between the capacitor and the sampling resistor was obtained,the capacitance and dielectric loss of the capacitor were calculated,and the data map for large signal operation of MLCC was established.The results show that when the AC voltage is constant,the capacitance increases with the increase of the bias voltage.When the AC voltage is small,the loss almost does not change with the change of the bias voltage.Under high DC bias,the capacitance and dielectric loss increase with the increase of the AC voltage.Under certain bias voltages,the capacitance does not change with the change of the AC voltage within a wide range.The capacitance could keep constant when the bias voltage and the AC voltage are changed at the same time.As a result,the contradiction between the existing electrical parameters of the materials or components and practical application requirements can be partially solved.