Abstract: Two high gain K band MMIC LNAs (low noise amplifiers) on an advanced 0.25μm PHEMT process are reported.A structure with three cascaded circuits is used for increasing the gate width without limit.Source feed inductors appropriate for obtaining a good noise figure (NF) and high gain are adopted.A new resistor and capacitor network attached to the sources and drains is applied to suppress low frequency oscillations.For convenience, the same set of negative and positive voltage sources is provided through the resistance in the chip to the three-cascade circuit, which performs very well.The values of VSWin and VSWout of LNA2 are less than 2.The small signal gain from 24GHz to 26.5GHz reaches to 24dB and the noise figure (NF) is less than 3.5dB.Both LNAs have wide dynamic ranges and their chip areas are small,with dimensions of 1mm×2mm×0.1mm.The output power of the LNAs is greater than 15dBm at the 1dB compressed point.These LNAs can be employed in front of a 24GHz radar and a 26.5GHz local distribution system (LMDS) .

Key words: PHEMT, K band, MMIC, high gain, low noise amplifier, layout EM simulation