Complex Filters for Short Range Wireless Networks

Abstract

The design of low-voltage complex filters using current mirrors for wireless receivers is presented in this chapter. Complex signal processing is an attractive technique for removing the image signals that appear in transceiver architectures. The problem from the presence of image signal in low-IF architectures is caused by the down-conversion operation realized by complex mixing. The realization of complex filters is achieved by employing an appropriate transformation to the corresponding conventional real filters. Two systematic methods for designing high-order complex filters are presented i.e. the leapfrog and the topological emulation techniques, where the employed active elements are low-voltage current mirrors. Thus, like in previous chapter, the offered benefits are the capability of low-voltage operation, the electronic tuning of their frequency responses and the absence of resistors. A twelfth-order complex filter function has been realized by employing the aforementioned techniques, where the performance of the corresponding topologies, fabricated in AMS 0.35 μm CMOS process, has been experimentally verified. Also, a detailed test setup for the measurement of the fabricated chip, including the interface for V/I and I/V conversion, is also provided.