Linear Vector Signal Generator for X-band Communication

This paper presents a scheme of extending the operating frequency range of an existing vector signal generator with the help of frequency-doubler. Since the frequency doubler generates the second harmonic of the input signal, which is non-linear, its compensation is essential for a linear transmitter output. A neural network-based digital predistorter is presented to linearize the frequency doubler. For proof of concept, the X-band frequency has been selected in which an input frequency of 5.5 GHz is shifted to 11 GHz. The results are validated using the experimental setup with 5 MHz Long-Term Evolution signal and the corrected EVM is found to be 2.031%.