Therefore, the peak-to-average ratio of the input signal will determine how close to saturation the PA can operate and still behave linearly once the predistortion coefficients are applied.
Equipment accuracy as well as the bandwidth and peak-to-average ratio of the input training data may have some impact on the accuracy of the measured response.
For these measurements, there appears to be a correlation between the peak-to-average ratio of the signal used and the AM/PM response, with the small peak-to-average ratio signals at the top and the large peak-to-average signals at the bottom of the graph.
This operating point is a function of the peak-to-average ratio of the PA as well as the PA transfer function used in the simulation.
Figure 12 shows the simulated power spectral density (PSD) results obtained for the GaAs PA using a one-user W-CDMA signal with a peak-to-average ratio of 5.
The CDMA signal is simulated using a UFX-CDMA generator, which produces a band-limited spectrum of filtered and upconverted noise that has a peak-to-average ratio of 12 dB that is reportedly representative of a CDMA base station spectrum with one pilot, sync and paging channel, and six traffic channels.
Typical measurements of the SA1056 amplifier with +34 dBm CDMA output power (in the primary channel) and a 12 dB peak-to-average ratio are shown in Figure 8.
This conversion to digital broadcasting places significant demands on a transmitter's power amplifier and RF power transistors because the signals have very high peak-to-average ratios
Seven New Devices Tailored Specifically for Signals with High Peak-to-Average Ratios Are Now Available
However, to provide top performance, the devices must be created specifically for use in applications with high peak-to-average ratios such as Doherty amplifiers.
The AD8364 is ideally suited for next-generation cellular infrastructure equipment using complex signals with constantly varying peak-to-average ratios
, such as CDMA2000, W-CDMA, and TD-SCDMA.
The MT1560 increases design margin by providing better peak output power (+67dBmV), better linearity (HD3 of -55dBc @ 61dBmV, 65MHz) and higher output range (59 dB gain range) than competitive products, allowing cable-modem designs to take advantage of these more complex modulation schemes with higher peak-to-average ratios