Nonlinear system behavioral modeling using reduced transmitter observation receiver bandwidth

A new approach for modeling wideband power amplifiers (PAs) using a reduced transmitter observation receiver (TOR) bandwidth is proposed. The general sampling theorem (GST) was used to lower the bandwidth requirement of the TOR. This approach highlighted that linearization should be carried out prior to the application of GST; two digital predistortion approaches using reduced TOR bandwidth were used for this purpose. Measurements were conducted using a 250-W Doherty PA driven with a 20 MHz WCDMA input signal. Good agreement between the modeled and the measured output spectrum was found across 100 MHz when the TOR bandwidth was reduced as low as 27.65 MHz.