Low-voltage Bluetooth/ZigBee complex filter using current mirrors

Complex signal processing is an attractive technique for removing the image signals that appear in transceiver architectures. The realization of complex filters is achieved by employing an appropriate transformation to the corresponding conventional real filters. A novel complex filter topology realized by employing current mirrors as active elements is introduced in this paper. Attractive characteristics are the capability of low-voltage operation, the electronic tuning of its frequency response and the absence of passive resistors. A 12^th-order complex filter has been designed in order to meet the Bluetooth and ZigBee standard requirements. The performance of the filter has been evaluated through simulation results by employing AMS 0.35μm CMOS process, where the most important performance factors have been considered.