High-Resolution ACLR Measurement Architecture for Adaptive Feedforward Amplifiers

One of the most restrictive linearity constraints to RF transmitter nonlinearity is the unwanted emission immediately outside the channel bandwidth, mostly known as adjacent channel leakage ratio (ACLR). In this paper, novel architecture design rules are presented for ACLR-level measurement in feedforward adaptive amplifiers. Both main and distortion signal power levels are obtained without any masquerading effect and with minimum component utilization. A prototype implementation is introduced to validate the proposed design rules, and a commercial spectrum analyzer is used for accuracy checking. Finally, the thermal stability has been tested for the -20^degC to 70^degC range.