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High performance channelizers, tunable notch filters, and silicon-based antennas for RF to millimeter-wave communication systems
Abstract
This thesis first presents a 26-channel channelizer based on the mammalian cochlea and covering the 20-90 MHz band. Each channel has a 6-pole frequency response with a constant absolute bandwidth of 1.4 MHz at 20-30 MHz, and a constant fractional bandwidth of 4.5±0.6% at 30-90 MHz, and is built entirely using lumped elements. Measurements show an S₁₁ < -12 dB at 20-90 MHz, a loss of 4-7 dB, > 40 dB isolation between the channels, and agree well with simulations. The applications areas are in communication systems with very high levels of interferes and in defense systems. In another project, tunable lumped-element bandstop filters for the UHF-band cognitive radio systems are presented. The 2-pole filters are implemented using lumped elements with both single- and back-to-back silicon varactor diodes. The single diode filter tunes from 470 to 730 MHz with a 16-dB rejection bandwidth of 5 MHz and a filter quality factor of 52-65. The back-to-back diode filter tunes from 511 to 745 MHz also with a 16-dB rejection bandwidth of 5 MHz and a quality factor of 68- 75. Both filters show a low insertion loss of 0.3-0.4 dB. Nonlinear measurements at the filter null with [delta]f = 2 MHz show that the back-to-back diode filter results in 12-dBm higher third order intermodulation intercept point (IIP3) than the single diode filter. A scaling series capacitor is used in the resonator arm of the back-to-back diode filter and allows a power handling of 25 dBm at the 16 dB rejection null. The cascaded response of two tunable filters is also presented for multi-band rejection applications, or for a deeper rejection null (> 36 dB with 0.6 dB loss at 600 MHz). The topology can be easily extended to higher-order filters and design equations are presented. The third project presents on-chip slot-ring and horn antennas for wafer-scale silicon systems. A high efficiency is achieved using a 100 [mu]m quartz superstrate on top of the silicon chip, and a low loss microstrip transformer using the silicon backend metalization. A finite ground plane is also used to reduce the power coupled to the TEM mode. The slot-ring and 1- [lambda]²/₀ horn achieve a measured gain of 0-2 dBi and 6- 8 dBi at 90-96 GHz, respectively, and a radiation efficiency of ̃50%. The horns achieve a high antenna gain without occupying a large area on the silicon wafer, thus resulting in a low cost system. The designs are compatible with either single or two-antenna transceivers, or and with wafer scale imaging systems and power-combining arrays. To our knowledge, this is the highest gain on-chip antenna developed to-date. Finally, differential on-chip microstrip and slot-ring antennas for wafer-scale silicon systems are presented. The antennas are fed at the non- radiating edge which is compatible with differential coupled-lines, and are built on a 0.13-[mu]m CMOS process with a layout which meets all the metal density rules. A high radiation efficiency is achieved using a 100 [mu]m quartz superstrate placed on top of the silicon chip. Both antennas achieve a measured gain of ̃3 dBi at 91-94 GHz, with a -10 dB S₁₁ bandwidth of 7-8 GHz and a radiation efficiency of >50%. The designs are compatible with single and multi-element transceivers, and with wafer-scale imaging systems and power combining arrays. To our knowledge, this is the first demonstration of high- efficiency on-chip differential antennas at millimeter- wave frequencies
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