一种基于负电容的新型带宽扩展技术

A new bandwidth extension technology based on negative capacitance

由于传统的电感峰化带宽扩展技术使用电感导致芯片面积大大增加,加源极退化电阻和电容的技术导致电路的DC增益减小,因此,文中提出一种基于负电容的新型带宽扩展技术,以有效解决上述两个问题。该技术利用两个交叉耦合的MOSFET将正电容转换成负电容,产生的负电容可以抵消负载电容的影响从而扩展带宽。首先,给出负电容带宽扩展电路的电路原理图,并运用小信号电路分析方法和S域电路分析方法得到负电容带宽扩展电路的小信号等效电路;然后,利用该小信号等效电路计算出负电容带宽扩展电路的传输函数,根据此传输函数分析得到负电容带宽扩展电路的稳定性条件;再运用拉普拉斯逆变换的方法得到负电容带宽扩展电路的时域阶跃响应表达式;最后,在Cadence IC617仿真工具中,运用理想模型对该负电容带宽扩展电路进行详细仿真分析,得到2.27倍的带宽扩展效果。

As the traditional inductance peaking bandwidth extension technique uses inductance to greatly increase the chip area,and the technique of adding source degeneration resistors and capacitors causes the reduction of DC gain of the circuit,a new bandwidth expansion technology based on negative capacitance is proposed to effectively solve the above two problems. In this technology,two cross-coupled MOSFETs is used to convert the positive capacitance into negative capacitance,which can counteract the influence of the load capacitance to expand the bandwidth. The circuit schematic diagram of the negative capacitance bandwidth expansion circuit is given. The small signal circuit analysis method and S-domain circuit analysis method are used to obtain the small signal equivalent circuit of the negative capacitance bandwidth expansion circuit. The small signal equivalent circuit is used to calculate the transmission function of the negative capacitance bandwidth expansion circuit,and according to the analysis of the transmission function,the stability condition of the negative capacitance bandwidth expansion circuit is obtained. The Laplace inverse transform method is used to obtain the expression of time-domain step response of the negative capacitance bandwidth expansion circuit. In the Cadence IC617 simulation tool,the ideal model is used to perform a detailed simulation analysis for the negative capacitance bandwidth extension circuit,and the bandwidth expansion effect of 2.27times has been obtained.