Time- and Frequency-Domain Optimization of Sparse Multisine Coefficients for Nonlinear Amplifier Characterization

For the testing of nonlinear power amplifiers, this paper suggests an approach to design optimized multisine signals that could besubstituted for the original modulated signal. In the design of multisines, complex coefficients should be determined to mimic the targetsignal as much as possible, but very few methods have been adopted as general solutions to the coefficients. Furthermore, no solid methodfor the phase of coefficients has been proven to show the best resemblance to the original. Therefore, in order to determine the phase ofmultisine coefficients, a time-domain nonlinear optimization method is suggested. A frequency-domain-method based on the spectralresponse of the target signal is also suggested for the magnitude of the coefficients. For the verification, multisine signals are designed toemulate the LTE downlink signal of 10 MHz bandwidth and are used to test a nonlinear amplifier at 1.9 GHz. The suggested phaseoptimizedmultisine had a lower normalized error by 0.163 dB when N = 100, and the measurement results showed that the suggestedmultisine achieved more accurate adjacent-channel leakage ratio (ACLR) estimation by as much as 12 dB compared to that of theconventional iterative method. KCI Citation Count: 2