@article{mazzaro_steer_gard_2010, title={Intermodulation distortion in narrowband amplifier circuits}, volume={4}, ISSN={["1751-8733"]}, DOI={10.1049/iet-map.2009.0281}, abstractNote={The contribution of bandpass filter memory to intermodulation distortion in narrowband amplifier circuits is examined. A method for generating multisines from filtered switched tones is presented, and techniques for measuring an amplifier's IP3 and extracting a filter's passband using these multisines are developed. It is shown that amplified filtered pulses produce intermodulation distortion in frequency-hopping communication systems. In the experimental study, 465 and 900-MHz Chebyshev bandpass filters are considered.}, number={9}, journal={IET MICROWAVES ANTENNAS & PROPAGATION}, author={Mazzaro, G. J. and Steer, M. B. and Gard, K. G.}, year={2010}, month={Sep}, pages={1149–1156} }
 @article{mazzaro_gard_steer_2010, title={Linear amplification by time-multiplexed spectrum}, volume={4}, ISSN={["1751-858X"]}, DOI={10.1049/iet-cds.2009.0263}, abstractNote={A new waveform processing technique for reducing intermodulation distortion (IMD) generated by an amplitude-modulated signal is presented. The technique eliminates amplifier-generated IMD by time-multiplexing portions of the signal spectrum prior to amplification. The input signal is described as a sum of sinusoidal signals. The peak-to-average ratio of the time-multiplexed amplifier input is lower than that of its non-multiplexed counterpart, but it contains spectral aliases at multiples of the switching frequency. Thus, the reduction in distortion of the desired amplified signal is achieved at the expense of momentarily widening the signal bandwidth. Following amplification, the desired signal is recovered using a bandpass filter which spreads the signal in time and narrows its bandwidth. An analytical expression for distortion reduction when amplifying two multiplexed carriers is developed along with measurements verifying the theory. Distortion reduction is demonstrated experimentally at 3.6 GHz for 2 20 multiplexed carriers, and linear recovery is demonstrated for four multiplexed carriers. The technique reduces third-order IMD by 8 22 dB in experimental measurements of three different amplifiers. The presented technique has the unique property of improving linearity without requiring feedback, feedforward cancellation or calibration.}, number={5}, journal={IET CIRCUITS DEVICES & SYSTEMS}, author={Mazzaro, G. J. and Gard, K. G. and Steer, M. B.}, year={2010}, month={Sep}, pages={392–402} }
 @article{saunders_mazzaro_steer_2010, title={Robust reduced-order modelling of distributed linear networks}, volume={4}, ISSN={["1751-8733"]}, DOI={10.1049/iet-map.2009.0554}, abstractNote={Foster's canonical form provides a causal bridge between the transfer function representation of the characteristics of a distributed structure and both time-domain and frequency-domain non-linear circuit simulation. It is particularly advantageous in modelling bandpass-like characteristics. In the modelling procedure, a transfer function having Foster's canonical form is fitted to measured or simulated data which may not have an inherent pole-zero description. Even if there is a good transfer function representation, the number of poles required for a reasonable fit is not known a priori which can lead to poor models that may cause convergence problems during either fitting or simulation. In this study, an extension of Foster's model is developed and a robust procedure for fitting the transfer function to data without a priori knowledge of the number of poles is presented. A robust stamp for implementation of the model in a transient circuit simulator is developed.}, number={7}, journal={IET MICROWAVES ANTENNAS & PROPAGATION}, author={Saunders, C. S. and Mazzaro, G. J. and Steer, M. B.}, year={2010}, month={Jul}, pages={962–973} }