用对数域电流模式积分器实现的高频集成滤波器

High Frequency Integrated Filters Using Log-Domain Current Mode Integrators

文本提出了全差动对数域电流模式积分器，该积分器的时间常数受参考偏流控制，其直流增益可达６０ｄＢ，在高频它具有比较平坦的相频特性。用该积分器设计的二阶滤波器和１ｄＢ波纹五阶Ｃｈｅｂｙｓｈｅｖ低通滤波器，计算机仿真显示，“实际”频响特性几乎是理想的，且频率可在很宽的范围内调控，这种滤波器具有很低的ＴＨＤ。

A log-domain current mode integrator with fully differential structure is proposed. The integrator time-constant is tUnable by varying a reference bias current, and the DC gain can reach 60dB .Also, it has natter Phase characteristics at high frequencies. By use of the integrator, a second order filter and a fifth order Chebyshev lowpass filter wb 1dB ripples are designed .The simulation demonstrates that the 'real' freqUency responses are nearly ideal,the cutoff frequency can be adjusted over a wide range and the filters have low THD.