Ka-band MMIC Power Amplifier Based On GaN HEMT

With the development of the active phased array radar, it has been more and more high integration and miniaturization. And it is essential to improve the output power, power add efficiency and reduce the size of the power amplifier. Because of the advantages of high breakdown voltage, stable chemical properties, resistance to radiation ability, thermal conductivity, high power density, good power add efficiency, the GaN-based HEMT power amplifier has become one of the most promising power amplifiers, and has received extensive attention in the military and civil field. With the improvement of working frequency of the next generation of radar system, the development of millimeter wave GaN power amplifier is imminent. Based on analysis of the physical model of GaN high electron mobility transistor(HEMT) devices and passive components, the Ka-band GaN HEMT monolithic microwave integrated power amplifier are designed and last good tested results are obtained. The main work is as follows:At first, this paper introduces the physical structure and working principle of GaN HEMT which is the active components in the power amplifier. Complete the modeling and simulation of the passive devices, such as spiral inductor, MIM capacitance, by using HFSS software, getting the relationship between the value of the device, quality factor and the physical size.In the basis of the above study, completing the design of Ka-band GaN HEMT monolithic microwave integrated power amplifier. Mainly involves the single stage power amplifier design, the topology of the multistage power amplifier design, bias circuit design, stability of circuit design, matching network and power combiner network design. Overall circuit is simulated by using ADS, and in order to improve the accuracy of results, full-wave method of moments(Momentum) of ADS is used to simulating the matching networks.At last, the power amplifier MMIC are taped out and measured on wafer. At the 33.5GHz~34.5GHz band, the output power is higher than 34 dBm, the power gain is higher than 7dB, the gain flatness is ±0.5dB and the power add efficiency(PAE)is higher than 8%. At the frequency of 34.2GHz, the output power can reach 34.9dBm, the power gain is 7.9dB and the PAE is 9.2%.