A Ku-band 1-Watt two stage power amplifier MMIC for space with 52% Power added efficiency

This paper presents the design and measured performance of a novel Ku-band two stage power amplifier monolithic microwave integrated circuit (MMIC) for space use. The circuit is designed using 0.25µm GaAs psuedomorphic high-electron mobility transistor (PHEMT) technology offered by UMS foundry. For two stage amplifier, measured performance shows 52% of power added efficiency (PAE) and 29.8 dBm of output power at 2-dB gain compression into a 50Ω load at 13 GHz frequency. The two stage power amplifier achieves more than 20dB of gain and second harmonic level of less than 30 dBc with reference to fundamental signal. To the best of the authors' knowledge PAE achieved in this two stage design is better than earlier reported PAEs at this frequency range for GaAs pHEMT MMICs. State-of-the-art efficiency performance is achieved through careful design of output matching network for second stage transistor. The MMIC is also tested in connectorised test module where thermal performance of the amplifier is also checked. Dual stage amplifier shows minimal variation of output power from ambient to hot (+65°C). All the measurements were carried out in continuous wave condition.