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Analog blocks intended for software defined radio have to be targeted to multi-standard operation trying to guarantee at any time a near optimal power-performance trade-off. A novel approach to design a digitally programmable low pass filter (LPF) and variable gain amplifier (VGA) is here defined. These baseband blocks are driven by a Network-on-Chip that is able to set performances like cut-off frequency, selectivity, noise, and gain conveniently adapting the power consumption. The LPF provides a wide frequency tuning range between 0.35MHz and 23.5MHz with an adaptive integrated noise level between 85µVrms and 163µVrms and a current consumption that moves from 1.5mA to 18mA. The VGA is made up of 2 cascaded gain stages and provides a gain range from 0dB to 39dB. The prototype was realized in 0.13µm CMOS technology. Measurements results validate the adopted approach.

The 4th generation of wireless systems needs lowmethodologies were proposed to achieve frequency power integrated transceivers that can be reconfigured in flexibility in continuous time filters [1][2] [3]. These design order to satisfy different standard requirements. Standard examples basically exploit the Gm-C topology, a good analog blocks are often not suitable for this step towards the option to implement low-power filters and obtain frequencyfuture because of their lack of flexibility. We defined a novel power flexibility conveniently playing with the approach to make Active-Gm-RC biquadratic cells completely transconductances and/or capacitors. But this structure, due reconfigurable. The biquad provides digitally programmable to its open loop operation, has limited dynamic range, poor bandwidth and hence power consumption with a fully linearity, and it is parasitic sensitive. The Active-Gm-RC bicustomizable cut-off frequencies range. Besides, the noise level quad cell has been selected as reference structure for this can be conveniently modified leading to a further power work because it is an energy efficient solution that saving. We exemplified the use of this basic building block in guarantees good linear performance at the same time. the design of a flexible low-pass filter for a zero-IF transceiver.A 2nd/4th/6th order Butterworth filter was implemented with aIn this paper, we present a simple but effective approach continuous cut-off frequency tuning between 330 KHz and 24.6 to make Active-Gm-RC bi-quadratic cells fully MHz and with a current consumption range between 0.6mA to reconfigurable and so able to be implemented in a SDR front 26mA.end. The defined approach exploits digitally programmable I. INTRODUCTION components arrays and allows the biquadratic cell providing software defined cut-off frequency, noise level and Software Defined Radio (SDR) is becoming a key part of selectivity. In the first section, the Active-Gm-RC cell is all next generation radio development. It provides an briefly described and the main parameters are identified in efficient and comparatively inexpensive solution to the order to provide all the flexibility features needed in a SDR problem of building multimode, multi-band, multifunctional front-end. The second section introduces the concept of wireless devices that can be adapted, updated, or enhanced components arrays as milestone of the entire reconfigurable by using software upgrades. A SDR is basically a transceiver structure. We will describe the active and the passive in which, ideally, all aspects of its operation are determined digitally controlled networks that enable different levels of using reconfigurable elements. Therefore, to accommodate flexibility. Finally, the last section describes a flexible filter the ever-changing standards specifications, it is necessary to design example that has the reconfigurable Active-Gm-RC introduce flexible architectures which can be used with biquadratic cell as basic structure. Simulations results are multiple standard...

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