Scaling of low-frequency noise in resistive FET mixers

The low-frequency noise in resistive FET mixers is investigated. The origin and the mechanism of creation are described using simplified equivalent circuits. Measurements on a single-ended mixer, as well as idealized simulations and formulas show the influence of LO frequency and gate width. The results confirm the previously proposed existence of two noise sources: FET channel and intrinsic gate load resistance. Furthermore, they prove that low-frequency noise increases rapidly with increasing LO frequency (+40dB/decade). The dependence on FET gate width is about +30dB/decade for the channel noise and about +10dB/decade for the noise of gate resistors.