This article reports on Si/AlGaN/GaN HEMT MMICs for

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-band frequency generation. A

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-band voltage-controlled oscillator (VCO), a

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-band frequency tripler, and a

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-band frequency quadrupler are designed to reach good phase noise, output power, and harmonic rejection in the

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-band. The VCO presents an experimental frequency tuning range of 21.8–25.2 GHz, and it enables direct integration with a commercial phase-locked loop (PLL). The tripler exhibits a peak output power of 3 dBm with a 3-dB bandwidth between 90-and 108-GHz output frequencies. The quadrupler, which is based on the integration of two doublers, one interstage buffer amplifier and a two-stage output buffer amplifier, achieves more than 10-dBm output power and better than 25-dB harmonics suppression over the frequency range of 89–100 GHz. The VCO and the quadrupler are also integrated into a fully integrated

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-band signal source with a frequency tuning range from 91.6 to 100.3 GHz and an output power of 12–16 dBm. Typical phase noise of

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126 dBc/Hz is measured at 10-MHz offset from the carrier. To the best of the authors’ knowledge, this is the highest integration level reported for a

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-band signal source in GaN HEMT MMIC technology. In addition, state-of-the-art far-carrier phase noise for

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-band signal sources based on integrated resonators is presented.