Power-Scalable Wideband Linearization of Power Amplifiers

In this paper, a wideband RF power amplifier (PA) linearization technique based on the addition of a linearization amplifier (LA) is proposed. The technique is suitable for low-powered and low-cost small cell and fifth-generation (5G) large-scale multi-antenna PA designs since its power and cost overhead does not increase with the input signal bandwidth and because they are scalable with the power range and cost of the PA. In-depth analysis of the proposed technique is provided and its linearization improvement mechanisms are described. As a proof of concept, a prototype LA was designed and fabricated to linearize a broadband 6-W class-AB PA with a center frequency of 850 MHz. When stimulated by a wideband 40-MHz signal, the PA's adjacent channel leakage ratio (ACLR) was improved by up to 13 dB after the addition of the LA. This enabled the PA to achieve an ACLR of about -45 dBc without the use of any other linearization techniques. Furthermore, significant ACLR improvements were observed for even signals with wider bandwidths up to 160 MHz.