A Tunable Wideband Frequency Synthesizer Using LC-VCO and Mixer for Reconfigurable Radio Transceivers

Abstract

This paper proposes a novel wideband LC-based voltage-controlled oscillator (VCO) for multistandard transceivers. The proposed VCO has a core LC-VCO and a tuning-range extension circuit, which consists of switches, a mixer, dividers, and variable gain combiners with a spurious rejection technique. The experimental results exhibit 0.98 to 6.6 GHz continuous frequency tuning with −206 dBc/Hz of FoM T , which is fabricated by using a 0.18 µm CMOS process. The frequency tuning range (FTR) is 149%, and the chip area is 800 µm × 540 µm.

A Wide Tuning-Range CMOS VCO with a Tunable Active Inductor

“…The varactors limited the tuning range within 30% due to the maximum to the minimum capacitance ratio of the varactor and the parasitic effect [1][2][3]. Therefore, various techniques have been proposed to enhance the tuning range of VCOs, such as switched capacitor arrays [4][5][6][7][8], switched inductors [9][10][11], and tunable active inductors (TAIs) [12][13][14][15][16]. TAI is one of the good candidates due to its small size, high , widely tunable inductance, and large inductance compared to those of the spiral inductor [17,18].…”