Using Modified Bessel Functions for Calculations of Drain Current Harmonics in a MOS Transistor Operating in Moderate Inversion

This work was supported by the NSERC, Canada, by the Portuguese Foundation for Science and Technology, and by the Academy of Finland.The paper describes evaluation of drain current harmonics in a MOS transistor operating in moderate inversion and strong saturation. The dependence of the drain current on the gate-source and drain-source voltages is described using a simplified 'reconciliation' model developed by Y. Tsividis. Then, in the proposed model the current components corresponding to the terms depending exponentially on normalized gate-source and/or drain-source modulating sinusoidal voltage are evaluated using modified Bessel functions. This approach allows one to omit the small-signal requirement for modulating signals, and calculate the first, second and third harmonics of the drain current caused by the gate-source or drain-source voltages and also find the intermodulation terms. The results are applied to the design of low-distortion low-voltage amplifiers. The recommendations are confirmed by simulations.publishe

On OFDM Link Performance under Receiver Phase Noise with Arbitrary Spectral Shape

This article addresses the signal distortion caused by receiver phase noise (PN) on OFDM waveforms in direct-conversion radio receivers. A closed-form solution for the observed signal-to-interference-plus-noise ratio (SINR) is derived, describing the level of intercarrier interference (ICI) stemming from PN. Compared to existing literature, the analysis is valid for arbitrary oscillator spectral shape, the only assumption being that reasonably small phase noise values are observed. The analysis results can be used to derive practical circuit-level oscillator design criteria in terms of the allowable PN spectral density. The applicability and validity of the derived analysis are verified with extensive computer simulations.Peer reviewe