A high figure of merit and area-efficient low-voltage (0.7-1 V) 12 GHz CMOS VCO

This paper presents the design and experimental results of an area-efficient LC-based voltage controlled oscillator (VCO) which can operate from a supply voltage as low as 0.7 V (2 mW in power), while being suitable for RF applications. A transformer coupling technique is used to reduce the required silicon area by more than a factor of two, compared to earlier designs, while reducing the phase noise. A VCO occupying a 0.24 mm² of area was fabricated in a standard 0.18 μm CMOS process. With a 1 V supply, the 12 GHz VCO consumes 7.7 mW with a measured phase noise of -102.2 dBc/Hz at a 600 kHz offset. A tuning range of 400 MHz is achieved without using varactors. The VCO has an excellent figure of merit (FOM) of -183.4 dBc/Hz, compared to recent designs.