A 2-15 GHz VCO With Harmonic Cancellation for Wide-Band Systems

A 2-15 GHz SiGe VCO (voltage controlled oscillator) has been developed with a very low harmonic content. The design is based on the harmonic cancellation concept and uses a multiple-phase ring oscillator together with a wide-band active-weighted summer. The VCO results in an output power of -8 to -6 dBm and <; -50 dBc 3rd and 5th harmonic level at 2-15 GHz. The active area of the chip is very small (0.67 × 0.25 mm
²
) due to the lack of inductors, and the power consumption is 88-120 mW from a 2.5 V supply. To our knowledge, this is the first demonstration of a wide-band VCO showing a near-perfect sinewave output over a wide frequency range. The application areas are in built-in-self-test sources for wide-band radios and phased arrays.