This letter presents an inverted complementary cross-coupled voltage-controlled oscillator (VCO) to reduce its phase noise (PN) sensitivity to VCO gain ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$K_{\mathrm{VCO}})$</tex-math> </inline-formula> implemented in a standard 28-nm bulk CMOS technology. Unlike conventional complementary VCO, the proposed topology places the NMOS switching pairs on the top of the PMOS pairs to constitute the inverted complementary cross-coupled topology to minimize the low-frequency noise up-conversion by varactors when with a large <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$K_{\mathrm{VCO}}$</tex-math> </inline-formula> . This topology can achieve both low PN at far offset frequency and a desired large continuous frequency tuning range for high-resolution millimeter-wave radar simultaneously. For example, when <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$K_{\mathrm{VCO}}$</tex-math> </inline-formula> varies with control voltage from 40 to 509 MHz/V, the PN only changes 0.68 dB at 10-MHz offset. The fabricated prototype achieves a PN of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$-$</tex-math> </inline-formula> 133.63 dBc/Hz at 10-MHz offset from 18.9 GHz, and the corresponding figure-of-merit (FoM) is <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$-$</tex-math> </inline-formula> 185.5 dBc/Hz. The measured frequency tuning range is 18.75 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$-$</tex-math> </inline-formula> 20.75 GHz (10.13%).