77∼97 GHz LNA MMIC with 1 dB-Gain Flatness Using Short-Circuited Capacitor

A short-circuited capacitor in a matching circuit between the third and fourth stages of an LNA has been used to reduce an unwanted small-signal gain at 50~70 GHz and to flatten signal gain at an operating frequency of 77~97 GHz. The designed LNA shows a small-signal gain of 21.2 to 22.2 dB, a gain flatness of 1 dB, a noise figure of 5.7 to 6.9 dB, an input-reflection coefficient of -14 to -7 dB, an output-reflection coefficient of -26 to -3 dB, an isolation of -51 to -44 dB, and an 1 dB bandwidth of 20 GHz over a frequency range of 76.6~96.6 GHz. And the simulated power characteristic of the designed LNA present an 1 dB compression power, P
_IdB
, of -3 to -1 dBm over a frequency range of 76.6~96.6 GHz.