Modeling of an IQ RF-DAC with error-free LO-switching
Sprache des Titels:
2018 IEEE International Symposium on Circuits and Systems (ISCAS)
In this paper a state-space approach for modeling radio-frequency digital-to-analog-converters is presented. We explain the root cause of the sign-change error appearing in RF-DAC architectures with local oscillator (LO) switching and present its impact in time domain and on the spectrum of the output RF signal. The main contribution of this paper is a solution for the removal of the sign-change error. The
solution is implemented in a linear state-space model, considering
static nonlinearities of the switched-capacitor power amplifier cells. We demonstrate the feasibility of our approach by simulation results for LTE5, LTE10 and LTE20 signals and show that the out-of-band noise contribution of the sign-change error is completely removed. Additionally, the impact of static nonlinearities on the system is investigated.