Ka/Q Dual Band Linearizer

A dual band linearizer for high power amplifiers (HPAs) used for multi-platform satellite communication uplinks in the Ka- and Q- bands is described in this paper. Transmissions in these bands now utilize complex digital modulations to increase their bandwidth efficiency. HPAs made for these modulations must be linear in order to minimize distortion. To achieve the required linearity, amplifiers are operated at reduced power, which results in lower efficiency, larger and heavier HPAs, extra heat, and higher costs. Linearization is used to cancel distortion and allow HPAs to operate closer to their maximum power; especially at millimeter-wave (MMW) where power is costly. Linearizers typically cover a single frequency band. The linearizer discussed here operates at two critical MMW SATCOM bands. When operated with a suitable wideband HPA, it allows efficient linear operation over both bands and considerable savings over HPAs for the individual bands. It can be used with both TWTAs and SSPAs, but was developed for a TWTA application. It is believed to the first multi-band linearizer developed for MMW.