In order to meet increasing functional and operational requirements, the current consumption of circuitry in multi-standard and multifunctional handhelds must be reduced. This goal can be achieved by using adaptive circuits, which trade RF performance for power consumption on the fly. The design of an adaptive multimode image-reject downconverter (an oscillator and two mixers) was completed by Aleksandar Tasić, Su-Tarn Lim, Wouter A. Serdijn, and John R. Long from the Delft University of Technology, Delft, The Netherlands.
In the highest performance mode, the image-reject downconverter (quadrature mixers) has an input third-order intercept point of +5.5 dBm and conversion gain of 1.4 dB—all while drawing 10 mA from a 3-V supply. The adaptive oscillator achieves –123 dBc/Hz phase noise at 1 MHz offset from a 2.1-GHz carrier with 6 mA current. The downconverter satisfies the 2G/3G requirements at 1.8 to 2.4 GHz of roughly 20 mA. See "Design of Adaptive Multimode RF Front-End Circuits," IEEE Journal of SolidState Circuits, February 2007, p. 313.
