高频高线性度跨导电容滤波器

High Frequency and High Linearity Transconductance Capacitor Filter

为了提高滤波器的工作频率和线性度,提出一种新型跨导放大器。该跨导器采用差分和交叉耦合来改善跨导输入级直流传输特性的线性度,以及扩大输入电压允许范围;同时,为了稳定输出共模电平和增大动态范围,提出共模反馈电路和各支路增益调整方法。对该滤波器进行理论分析和验证,结果表明,Gm-C滤波器的截止频率为159.6MHz,过渡带宽大于45dB,动态范围为64dB,具有较好的高频和高线性度特性。

To improve the frequency and linearity of filter,a new transconductance operational amplifier was presented,in which cross-coupled differential structure was used to improve DC transmission characteristics of the transconductance input stage and extend the linear input voltage range.To stabilize output common-mode level and increase dynamic range of the filter,a CMFB circuit was proposed,along with gain adjustment method for each branch.Theoretical analysis was made,which was verified with simulation.Results showed that the Gm-C filter had a cutoff frequency of 159.6 MHz,a transition bandwidth greater than 45 dB and a dynamic range of 64 dB.