In this letter, a fully integrated receiver frontend which is composed of a low-noise amplifier and a down-conversion mixer is presented for multiband applications. Different from conventional concurrent or switched-type architectures, the proposed circuit uses varactors for the frequency tuning. In addition, broadband techniques are also employed to maximize the operating frequency range and to enhance the circuit performance. Using a standard 0.18 m CMOS technology, a 3-5 GHz receiver frontend is implemented for demonstration. With a LO power of 3 dBm and an IF frequency of 10 MHz, the circuit exhibits a conversion gain of 22 2 2 4 dB while the IIP3 and noise figure are better than 6 dBm and 17 dB, respectively, within the entire frequency range. Operated at a supply voltage of 2 V, the receiver consumes a dc power of 16 mW.Index Terms-Band selection, CMOS radio frequency (RF), down-conversion mixer, frequency tuning, low-noise amplifier (LNA), multistandard, receiver frontend.

In this paper, a novel circuit topology of low-noise amplifiers suitable for multi-band and multi-standard wireless applications is proposed. By employing a broadband input matching technique and vactors in the inter-stage and output matching networks, a compact LNA with continuous frequency tuning capability is realized. The proposed circuit is implemented in a standard 0.18-µm CMOS technology. Based on the measurement results, the LNA can operate from 2.9 to 3.5 GHz with a forward gain of 9±3 dB while consuming a dc power of 18 mW from a 1.8-V supply.Index Terms-CMOS RF, LNA, multi-band, multi-standard, tunable.