14.4 A Class F-1/F 24-to-31GHz power amplifier with 40.7% peak PAE, 15dBm OP1dB, and 50mW Psat in 0.13μm SiGe BiCMOS

The output power of power amplifiers (PAs) can be increased by using PA arrays and by combining individual PA output powers either on chip with linear combiners or in free space with antenna arrays [1,2]. Therefore, the output power of a PA element can be compromised by the array size. The overall array's power-added-efficiency (PAE) is predominantly determined by the unit PA, which is the most critical performance metric to contain thermal and reliability issues, especially in highly integrated large PA arrays, since thermal density will be proportional to the increase of power density. Class-F and Class-F
^-1
topologies are promising candidates for a high PAE at microwave and mm-Wave frequencies because on-chip high-Q passive components with a small form-factor will be readily available for a tuned load to terminate multiple harmonics appropriately [3]. Maintaining a high efficiency over a wide bandwidth, however, is challenging because of the narrowband nature of the high-Q networks. This paper presents a highly efficient Class-F
^-1
/F PA in 0.13μm SiGe BiCMOS achieving 39.3-40.7% PAE over 25 to 30GHz. In the PA, integrated on-chip passive load networks operate cooperatively to shape the load impedance for an in-band mode transition from Class-F
^-1
to Class-F, maintaining greater than 36.3% PAE over the entire operation band (24 to 31GHz, 25.5% of fractional bandwidth).