Fully reconfigurable active-Gm-RC biquadratic cells for software defined radio applications

The 4th generation of wireless systems needs low-power integrated transceivers that can be reconfigured in order to satisfy different standard requirements. Standard analog blocks are often not suitable for this step towards the future because of their lack of flexibility. We defined a novel approach to make active-Gm-RC biquadratic cells completely reconfigurable. The biquad provides digitally programmable bandwidth and hence power consumption with a fully customizable cut-off frequencies range. Besides, the noise level can be conveniently modified leading to a further power saving. We exemplified the use of this basic building block in the design of a flexible low-pass filter for a zero-IF transceiver. A 2nd/4th/6th order Butterworth filter was implemented with a continuous cut-off frequency tuning between 330 KHz and 24.6 MHz and with a current consumption range between 0.6mA to 26mA