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http://hdl.handle.net/11375/13072
Title: | The Design of Low-Voltage, micropower Voltage-Controlled Oscillators |
Authors: | Fakhr, Ahmed |
Advisor: | Deen, Jamal |
Department: | Electrical and Computer Engineering |
Keywords: | Electrical and Computer Engineering;Electrical and Computer Engineering |
Publication Date: | Dec-2004 |
Abstract: | <p>With the rapid increase in the market of portable wireless devices, the life time of the battery has become very important, especially in wireless medical telemetry, where it becomes very critical due to the nature of the application. As part of the wireless system, RF circuits are required to have low-power consumption as one of the ways to increase the device life time before the need to charge or change its battery. Meanwhile, the low-power RF circuit should maintain the basic noise and linearity performance required to guarantee an acceptable BER (Bit-Error Rate) at the receiver end. Furthermore, these circuits must be cheap and compatible with digital technologies.</p> <p>This thesis focuses on the design of CMOS voltage-controlled oscillators (VCO), as one of the building blocks ofa wireless transceiver. Power consumption reduction of the VCO is the main objective in the thesis. The first step to achieve the low-power requirement is to optimize the quality factor of the passive devices, such as inductors and capacitors. Therefore, we have introduced a new technique to enhance the quality factor of the monolithic inductors. This technique is based on decreasing the overall parasitic resistance while increasing the mutual inductance between the strips of the inductor. Momentum simulations are performed to compare between the proposed technique and another regular inductor that has the same inductance value. The proposed inductor shows 23% enhancement in its quality factor.</p> <p>Three ultra low-voltage yeas are presented. The first two yeas are designed to operate at frequencies equal to 600 MHz and 2.4 GHz. The novelty in these designs is the low-supply voltage with a value of 400 mY, which is about 100 mV below the threshold voltage ofthe transistor. Biasing in sub-threshold, leads to reducing the power consumption performance. These oscillators are the first RF oscillators to be biased in sub-threshold.</p> <p>The third oscillator was designed to operate at 6 GHz. In this design we have added another contribution, where we forward biased the body contact of the VCO to overcome the high frequency effects that occur in sub-threshold. The three oscillators are designed to operate with supply voltages of 350 mV, 400 mV and 450 mV, respectively. The oscillators have a minimum phase noise of -128 dBc/Hz, -123 dBc/Hz and -113 dBc/Hz at 1 MHz offset, respectively, and power consumption of 36 μW, 41 μW and 90 μW, respectively. These results show the minimum power consumption and supply voltage operation reported in the literature. In the analysis of these oscillators, discussions are given on the large signal performance of the oscillator and the effect of the inductor mismatch on the power consumption and the phase noise performance. From these three veos, the 600 MHz oscillator was measured. It operates with a supply of 430 mV, consumes 257 μW and has phase noise of -132.5 dBc/Hz at 600 kHz offset.</p> <p>To show the effectiveness of the low-power technique used with the above Yeas, another oscillator is designed at 2.4 GHz with a higher supply voltage of 1 V. The oscillator's phase noise is -123.1 dBc/Hz and it consumes 135 μW which is considered very good compared to other oscillators operating with the same supply voltage. Tuning is realized by using body-biasing of the oscillator. Therefore, we have presented a unique discussion on the effect of body-biasing on the performance ofthe oscillator. Measurments for this oscillator was obtained, however, it does not match the simulations due to the package parastics.</p> |
URI: | http://hdl.handle.net/11375/13072 |
Identifier: | opendissertations/7901 8979 4300143 |
Appears in Collections: | Open Access Dissertations and Theses |
Files in This Item:
File | Size | Format | |
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fulltext.pdf | 55.17 MB | Adobe PDF | View/Open |
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