A CMOS low noise amplifier for impulse radio ultra-wideband applications

The design and implementation of an Ultra-wideband (UWB) low noise amplifier (LNA) in 0.18 mum CMOS technology is presented in this thesis. A 3.1-10.6 GHz, single-stage, low noise amplifier (LNA) design employing a frequency dependent feedback network is reported. Post-layout simulations of the LNA demonstrated a power gain of 8 dB, an input matching of -13 dB, a minimum spot noise figure (NF) of 3.5 dB and an average NF of 4.4 dB. The amplifier exploits a combination of negative and positive feedback to attain a flat gain across the entire bandwidth with an input-referred 1 dB compression at -2.48 dBm, an input-referred second- and third-order intermodulation intercept points (IIP2, IIP3) at 10.71 dBm and 20.76 dBm, respectively. An ultra-wideband noise and power matching technique utilizing frequency dependent Miller's multiplication factors is presented.; The transient response to the fifth order derivative of a Gaussian monopulse input occupying a bandwidth of 6.6 GHz was demonstrated in simulations. The correlation coefficient between the input and the output monopulses is above 99% emphasizing the minimum distortion introduced by the amplifier.; The measured LNA demonstrated a voltage gain of 9.53+/-0.86 dB with a 3 dB band-width of 7.3 GHz, a minimum |S11| of -9.1 dB, a minimum NF of 6.4 dB, an IIP3 of 10.67 dBm while drawing 12mA of current from a 1.8V supply. It was observed during measurements and verified by electromagnetic (EM) simulations that the performance of the load inductor was degraded due to its increased parasitics to substrate which resulted in a degradation in the measured power gain performance compared to post-layout simulations. With the demonstrated voltage gain performance, the LNA is suitable for direct sequence (DS) UWB applications that operate in the lower band (i.e. 3.1-5.15 GHz).; The main contributions of this work include: (i) the implementation of a single stage frequency-controlled feedback LNA in the CMOS technology that spans the entire UWB spectrum; (ii) the analysis of Miller's multiplication factors and their variation with frequency which was exploited to facilitate the wideband power and noise matching with minimum passive components added at the input of the amplifier; (iii) the analysis for the equivalent two-port noise representation of the amplifier which illustrated how the optimum signal source susceptance needed for ultra-wideband noise matching has been modified by the proposed topology and how it could be approximated by a single passive component.