Analysis and Design of a Stacked Power Amplifier With Very High Bandwidth

In order to simplify and optimize the design process of stacked amplifiers, this paper presents a novel analytical method to dimension the input network for ideal output behavior. To verify this new structural design process, a fully integrated stacked power amplifier (PA) in 0.25-μm SiGe BiCMOS technology is proposed. The stacked architecture enables broadband matching networks, therefore the designed PA reaches a very high bandwidth of 800 MHz around 2 GHz. At 2 GHz, the small-signal gain is 23.8 dB. The output power in the 1-dB compression point and the saturated output power are 26.2 and 27.3 dBm, leading to a power-added efficiency (PAE) of 34% and 40%, respectively. Using a long-term evolution (LTE) modulated input signal without any predistortion, the amplifier reaches an average output power of 21 dBm and a PAE of 12%, fulfilling the LTE specifications in terms of adjacent channel leakage ratio and error vector magnitude.