摘要
半导体PN结具有电容的性质.在正向直流偏压下,理论计算表明,PN结扩散电容的对数与正向偏压成正比.实验发现,当正向偏压小于30mV时,这种线性关系是成立的;当正向偏压大于30mV时,会偏离这种线性关系.由于PN结还具有电阻特性,对交流信号的相位有影响.随着正向偏压增大,交流信号的相位变化出现一极值.如果将PN结等效为一个电容和一个电阻并联,就可以定性解释这种变化关系.
A capacitance is associated with a PN junction. Under a forward bias voltage, logarithm of the diffusion capacitance is proportional to the forward bias voltage theoretically. It has been found experimentally that the linear relationship is valid when the forward bias voltage is less than 30mV. A resistance is also associated with the PN junction, resulting in the phase change of an AC signal. With the increase of the forward bias voltage, a maximum value of the phase change is observed and the result is explained qualitatively by considering the PN junction as a capacitance and resistance in parallel.
出处
《物理与工程》
2009年第1期13-16,共4页
Physics and Engineering
关键词
PN结电容
正向直流偏压
扩散电容
势垒电容
交流信号相位
capacitance of PN junction
forward bias voltage
diffusion capacitance
barrier capacitance
phase of AC signal
