An Ultra-Compact 0.5˜3.6-GHz CMOS VCO with High-Q Active Inductor

In this letter, an ultra-compact and wide-tuning-range voltage-controlled oscillator (VCO) with high-Q active inductor is designed, implemented, and verified in a standard 0.18-μm complementary metal-oxide-semiconductor (CMOS) process. The proposed active inductor topology with feedback resistors not only achieves high quality (Q) factor but also features wide inductance-tuning-range, which are impractical in conventional passive solutions. Moreover, due to the use of active inductors in the LC tank, the chip area of the circuit is only 0.018 mm². With 1.8-V supply voltage and other tuning mechanisms, the VCO consumes 8.1~24.3-mW dc power. The VCO can be tuned from 0.5 GHz to 3.6 GHz, demonstrating a 151% frequency tuning range.