Sixteen-phase CMOS millimetre-wave voltage-controlled oscillator

A 16-phase complementary metal oxide semiconductor (CMOS) millimetre-wave voltage-controlled oscillator (VCO), which adopts an injected signal amplitude enhancing technique, is presented in this work. The oscillator consists of eight VCO cores coupled together to form a ring. In the coupling path, transmission line inductors are introduced to enhance the amplitude of the injected signal. As a result, the coupling factor between two nearby VCO cores is increased by a factor larger than one. This releases the strict trade-off between multi-phase imbalance and phase noise. The VCO adopting the amplitude enhanced technique was fabricated using 0.13 mu m CMOS radio frequency (RF) technology. The circuit oscillates from 19.69 to 23.48 GHz. The measured phase noise at 1 MHz offset ranges from -91 to -98 dBc/Hz. The entire circuit, including all output buffers, dissipates 50.4 mW from a 1.2 V DC supply. The calculated figure of merit for the VCO is 168.