An eighth order channel selection filter for low-IF and zero-IF DVB tuner applications

作者：Zou Liang; Liao Youchun; Tang Zhangwen^*

来源：Chinese Journal of Semiconductors, 2009, 30(11): 115002.

DOI：10.1088/1674-4926/30/11/115002

• Active RC filter
• Automatic frequency tuning
• Butterworth
• Channel selection filter
• CMOS processs
• Filter circuits
• Frequency attenuation
• Frequency-tuning
• Group delays
• In-band
• Input power
• Measurement results
• Power supply
• Resistor arrays
• Switched capacitor array
• Zero IF

An eighth order active-RC filter for low-IF and zero-IF DVB tuner applications is presented, which is implemented in Butterworth biquad structure. An automatic frequency tuning circuit is introduced to compensate the cut-off frequency variation using a 6-bit switched-capacitor array. Switched-resistor arrays are adopted to cover different cut-off frequencies in low-IF and zero-IF modes. Measurement results show that precise cut-off frequencies at 2.5, 3, 3.5 and 4 MHz in zero-IF mode, 5, 6, 7 and 8 MHz in low-IF mode can be achieved, 60 dB frequency attenuation can be obtained at 20 MHz, and the in-band group delay agrees well with the simulation. Two-tone testing shows the in-band IM 3 achieves-52 dB and the out-band IM3 achieves-55 dB with-11 dBm input power. This proposed filter circuit, fabricated in a SMIC 0.18 μm CMOS process, consumes 4 mA current with 1.8 V power supply.

• 出版日期2009
• 单位复旦大学