Diode-Based Piecewise Linear Tuning Design of Ku-Band Voltage-Controlled Oscillator

This letter presents two Ku-band LC-tank voltage-controlled oscillators (VCOs) with a diode-based piecewise linear voltage converter, which were fabricated using 0.18- $\mu \text{m}$ CMOS process of Taiwan Semiconductor Manufacturing Company (TSMC) and a 0.9-V supply voltage. By adjusting the voltage gain of a voltage converter, the nonlinearity tuning of the VCO can be compensated as a linear tuning characteristic. Type-I VCO achieves an operating frequency range of 14.28–14.68 GHz and a slight tuning sensitivity variation of 175–255 MHz/V. Type-II VCO achieves a 9.19% frequency tune range (FTR) and a small tuning sensitivity variation of 750–1300 MHz/V with a controlled-voltage variety of 0.6–1.8 V. The measured phase noise of Type-I and Type-II VCO was −108.81 and −112.06 dBc/Hz at a 1-MHz offset frequency from a carrier frequency of 14.28 and 14.2 GHz, respectively. The chip size of Type-I and Type-II VCO, including the voltage converter, was $0.675\times 0.51$ mm2 and $0.675 \times 0.525$ mm2, respectively. Two proposed VCOs only consume less than 3.3 mW.