A Fully Integrated CMOS Complex Filter for IEEE802.15.4 Standard
Zhong Lun-gui①② Yang Hai-gang① Liu Fei① Gao Tong-qiang① Zhang Hui①②
①(Institute of Electronics, Chinese Academy of Sciences, Beijing 100190, China) ②(Graduate University of Chinese Academy of Sciences, Beijing 100049, China)
Abstract：Complex filter is one of the major parts in low-if receiver to reject imagine signal. Considering the low-power requirement of IEEE802.15.4 standard, this paper presents a pseudo OTA with flexible configuration of common mode feedback block, which is suitable to use in cascade systems for its inner common mode feed-forward and common mode detection. A third-order Butterworth Gm-C complex filter is designed based on this OTA, its center frequency locate at 1 MHz, with a 1.3 MHz bandwidth, the in-band group delay ripple is less than 0.16 μs, its IRR(Imagine Rejection Ratio) can satisfy IEEE802.15.4 standard’s requirements. A frequency tuning method is also presented in this paper, it is simple and power efficiency comparing to traditional PLL tuning method.
2010, Vol. 32 
