Loading...
| Friend's email | |
| Your name | |
| Your email | |
| enter code | |
This page was sent successfuly
- Type of Document: M.Sc. Thesis
- Language: Farsi
- Document No: 47485 (05)
- University: Sharif University of Technology
- Department: Electrical Engineering
- Advisor(s): Atarodi, Mojtaba
- Abstract:
- In most radio receivers like superheterodyne receivers, a weak desired incoming signal is accompanied with many interferer signals that are much more powerful than the desired signal itself. These interferers, also called blockers, can cause a great disturbance in the functionality of the receiver. Due to gain compression and an increase in the noise figure (NF) of the receiver, the blockers should be filtered before the arrival at the output of the LNA. Because of the low quality factors of the available on chip inductors and in order to eliminate the out of band interferer signals and image frequency (in superheterodyne receivers), usually an external surface acoustic wave (SAW) filter is used. Due to low bandwidth and inability to adjust the center frequency of this type of filter, it is not possible to have multistandard receivers. Furthermore, because of the high cost of the external components, it is preferable to use only on chip elements in a receiver. In some refrences, the linearity and interferer problems are solved by excluding the low noise amplifier in the receiver with the price of an increase in the sensitivity of the receiver due to excess noise generated from the mixer. One approach to relax the tradeoff between the noise and linearity is using N-path filters with high quality factors as well as high linearity. A novel N-path filter using a complex impedance is designed to replace the frontend SAW filters in receivers with on-chip bandpass filters. It is demonstrated that the center frequency of the proposed filter can be tuned just by changing the value of some capacitances without the need to change the clock frequency. In addition, thanks to the use of smaller capacitors the silicon area is decreased compared to similar designs. The proposed bandpass filter is realized utilizing two gyrators and an arrangement of four baseband capacitors with NMOS switches, driven by 4-phase 25% duty cycle clock signals. This thesis also analyzes the performance of the proposed filter against imperfections such as thermal noise of the switches. It will be shown that the noise performance of the proposed circuit is in acceptable range
- Keywords:
- Gyrator ; Quality Factor ; Bandpass Filters ; N-Path Filter ; Complex Impedance
Digital Object List-
محتواي کتاب - view
Bookmark