片上自动调谐的可编程有源RC滤波器

研制了一款可编程6阶巴特沃斯有源RC滤波器.为提高滤波器中运算放大器的增益带宽积,设计了一种新型的前馈补偿运算放大器.为消除工艺偏差和环境变化对截止频率的影响,设计了一种片上数字控制频率调谐电路,并采用TSMC 0.18 μm CMOS工艺进行了流片.滤波器采用低通滤波结构,测试结果表明,3 dB截止频率为1～32 MHz,步进1 MHz,带内增益0 dB,带内纹波0.8 dB,2倍带宽处带外抑制不小于24 dBc,5倍带宽处带外抑制不小于68 dBc,滤波器等效输入噪声为340 nV/√Hz@1MHz,调谐误差为±3％.滤波器裸芯片面积0.87 mm×1.05 mm.采用1.8V电源电压,滤波器整体功耗小于20 mW.

Programmable Active RC Filter with on-Chip Automatic Tuning

A programmable 6 order Butterworth active RC filter was researched and fabricated.In order to improve the gain bandwidth product of the amplifier,a novel feed forward compensation amplifier was designed.In order to eliminate the effects of the process deviations and the environmental changes on the cutoff frequency,an on-chip digital controlled frequency tuning circuit was designed,and the circuit was implemented in TSMC 0.18 μm CMOS process.The filter adopted the low pass filter architecture.Test results show that the 3 dB cutoff frequency is from 1 MHz to 32 MHz,the step is 1 MHz,the band gain is 0 dB,the band ripple is 0.8 dB,the inhibition of 2 times of the bandwidth is more than or equal to 24 dBc,and more than or equal to 68 dBc at 5 times of the bandwidth.The equivalent input noise of the filter is 340 nV/√/Hz@1 MHz,and the tuning accuracy is ±3％.The bare chip area of the filter is 0.87 mm×1.05 mm.With the 1.8 V power supply voltage,the power consumption of the filter is less than 20 mW.