Q-, V-, and W-band power amplifiers utilizing coupled lines for impedance matching

This paper introduces the use of the coupled transmission lines structure for impedance matching networks which is suitable for power amplifier design at millimeter-wave frequency bands. The structure can replace the conventional stub matching networks and MIM (Metal-Insulator-Metal) capacitors for DC blocking. Five MMIC power amplifiers have been designed based on coupled lines impedance transformers at 35 GHz, 60 GHz and 100 GHz. The fabricated two-stage 35 GHz PA has a small-signal gain of 20 dB and input and output reflection coefficients of less than -10 dB and can deliver 16 dBm output power. The two-stage 60 GHz power amplifier shows 15dB of small-signal gain and less than -10 dB of reflection coefficients with the output power of 16 dBm. The 100 GHz amplifier has small-signal gain of 10 dB and 7 dBm output power.