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Design and Implementation of Complex Multi-Path Filters
, M.Sc. Thesis Sharif University of Technology ; Atarodi, Mojtaba (Supervisor)
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...
Design and Implenentation of a Bandpass Delta-sigma Modulator Using High-Q N-path Filter
, M.Sc. Thesis Sharif University of Technology ; Atarodi,Mojtaba (Supervisor) ; Sharifkhani, Mohammad (Co-Supervisor)
Abstract
Delta-Sigma Analog-to-Digital converters have been positioned themselves as robust reliable converters so far. The magic Of extracting high resolutions from low bit ADC has made them popular between designers. Previously, the noise-shaping magic was used in high-resolution applications such as high-quality audio signal converters. However, as the technology scales and proceeds, these converters are approaching RF applications, too. Power and OSR trade-off limits this progress. To increase OSR in bandpass delta-sigma modulators, more power should be consumed to increase the quality factor of loop filters. In this thesis, a systematic approach has been utilized. An n-path filter is employed...
Leakage Cancellation from Transmitter to Receiver
, M.Sc. Thesis Sharif University of Technology ; Atarodi, Mojtaba (Supervisor) ; Safarian, Amin Ghasem (Supervisor)
Abstract
The wideband code-division multiple access (WCDMA) system has been widely used for the third-generation wireless communication system. It uses Frequency division duplexing for two-way communication by a transceiver. Although a duplexer will significantly suppress the TX leakage signal (50dB-60dB), a residual attenuated signal still remains at the receiver input and act as a strong blocker which reduces the sensitivity of the receiver. For reducing the effect of the TX leakage on the RX performance, a band pass RF SAW filter is typically inserted between the LNA and the mixer to reject the TX leakage. However, this filter increases the system cost and size. This encouraged us to propose a novel...
Design of an N-Path Tunable Bandpass Filter for RF Range
, M.Sc. Thesis Sharif University of Technology ; Atarodi, Mojtaba (Supervisor) ; Sadughi, Sirous (Supervisor)
Abstract
A high-Q tunable bandpass filtered amplifier structure is proposed which is based on N-path Q enhancement. Using Fourier series analysis, frequency response of an N-path filter and aliasing effect of this filter is achieved. This effect is caused by frequency translation to bandpass frequency as harmonic fold back (HFB). It is shown that using an additional N-path filter with the same clock frequency but different clock phase HFB is reduced. The conditions for fold back elimination are derived from Fourier series expansions for switched signals. In order to realize HFB reduction and increasing stop-band rejection and Q factor, an LNA associated with N-path filter is added to each of the...
Improvement of LC Oscillators Phase Noise by Using N-Path Filters
, M.Sc. Thesis Sharif University of Technology ; Kavehvash, Zahra (Supervisor) ; Atarodi, Mojtaba (Co-Advisor)
Abstract
A novel low noise quadrature voltage-controlled oscillator (QVCO) with differential N-path filter is proposed in 0.18-μm CMOS technology. The said QVCO benefits from a cross-coupled structure and a current-reuse technology to produce the quadrature signal and to save power consumption and area, respectively. The new architecture reduces the phase noise by 8dBc/Hz at a 1MHz offset frequency for 2.4GHz oscillation frequency. QVCO consumes 9.8mW from 1.8V power supply when operating at 2.4GHz. QVCO has a frequency tuning range from 2.4GHz to 3GHz and achieves a FOM of 191dB at 1MHz offset. Switches of N-path filter are controlled by outputs of QVCO, so the center frequency of N-path filter is...
Designing a Low Power Transmitter for Medical Implant Communications Service
, M.Sc. Thesis Sharif University of Technology ; Safarian, Aminghasem (Supervisor)
Abstract
One of the most important parameters of an implanted device in the human body is its ability to operate for a long time to decrease the need for surgery in order to replace the battery. Therefore, the radio transceivers in these devices are designed in such a way to reduce the power consumption as much as possible. But, at the same time, it is crucial that the bit error rate be as small as possible to decrease the number of incorrect sent and received bits. Thus, the phase noise should also be as small as possible in order to reduce the bit error rate. In this thesis, a transmitter has been designed for Medical Implant Communications Service standard. In order to reduce the power...
Design and Simulation of an UWB RFID Reader
, M.Sc. Thesis Sharif University of Technology ; Fotowat Ahmady, Ali (Supervisor)
Abstract
Ultra-wideband (UWB) frequencies with low level of power spectral density, which is set by FCC standard, have long been utilized in many short range applications, namely sensor networks, indoor positioning and radar systems. As their name suggests, the ultra-wide bandwidth of this standard, covering frequencies from 3.1 to 10.6GHz, provides high data rate communications. Two of the most critical challenges toward UWB receiver design is narrow-band interference coexistence, including IEEE802.11a and jitter due to the very narrow width of the UWB pulse in time domain. General previously proposed solutions to receive these narrow pulses is based on correlation principle, which is very sensitive...
A Novel Simultaneous Frequency and Spatial Filtering Methodology for Beam-forming and Null-steering in Integrated Phased-Array Systems Using N-path technique
, Ph.D. Dissertation Sharif University of Technology ; Atarodi, Mojtaba (Supervisor)
Abstract
In the communication systems, there are two types of blockers: in-band and out-of-band. High frequency pre-filters and band-pass filters can be used to suppress the out-of band blockers. However, using these methods does not affect the in-band interferers. Spatial filtering by means of phased array antennas and using frequency filtering can suppress both types of interferers. In a typical phased array receiver, all of the received signals pass through active blocks (such as LNAs, active phase shifters, driver amplifiers, etc.) that amplify the interferers before canceling them. Therefore, because of the high strength of the interferers, the dynamic range of the front-end blocks preceding...
Analysis of the effects of clock imperfections in N-path filters
, Article Conference Proceedings - 13th IEEE International NEW Circuits and Systems Conference, NEWCAS 2015, 7 June 2015 through 10 June 2015 ; June , 2015 , Page(s): 1 - 4 ; 9781479988938 (ISBN) ; Kananian, S ; Khorami, A ; Fotowat Ahmady, A ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2015
Abstract
In this paper, the effect of imperfections on the behavior of N-path filters is investigated. Exact mathematical derivations are presented which describe the effect of clock skew and finite fall/rise time on the impedance transformation behavior of N-path filters. In the ideal case, the N-path filter is supposed to provide a short-circuit to the ground for undesired frequency contents and an open-circuit for the desired signal so that it lies within the passband of the filter. It is shown that clock skew and finite clock fall/rise time result in a non-zero impedance for frequency contents other than the clock frequency and a smaller impedance for the desired voltage. In a real circuit with...
Analysis and design of 4-path filter using gyrator based complex impedance
, Article AEU - International Journal of Electronics and Communications ; Volume 70, Issue 11 , 2016 , Pages 1532-1542 ; 14348411 (ISSN) ; Behmanesh, B ; Atarodi, S. M ; Sharif University of Technology
Elsevier GmbH
Abstract
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 filter can be tuned solely 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 reduced compared to similar designs. The high-Q 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 paper also analyzes the performance of the proposed filter against imperfections such as thermal...
Designing a Low Power Receiver for Medical Implant Communications Service
, M.Sc. Thesis Sharif University of Technology ; Safarian, Amin Ghasem (Supervisor)
Abstract
One of the most important parameters of implanted chip in body is its ability to work for a long time without the need for battery change. Hence designing radio frequency transceivers used in these chips should be done with the lowest possible power consumption. Of course it should be noticed that for correct communication, standard specifications must be meeted. In this thesis, a receiver in medical implant communication service standard with the goal of minimal power consumption is designed. In circuit design different challenges such as low inductor quality factor, threshold voltage of transistors and usual trade-offs between receiver parameters are faced. Therefore, previous used...
Design and Implementation of a UWB RFID Reader
, M.Sc. Thesis Sharif University of Technology ; Fotowat Ahmady, Ali (Supervisor)
Abstract
Ultra-wideband (UWB) receivers have long been utilizied as a low-power solution for many applications, namely positioning, sensor network, and radar systems. As their name suggests, owing to the ultra-wide bandwidth nature of these receivers, which cover frequencies from 3.1GHz all the way to 10GHz, they entail many challenges at all levels of abstraction. Two of these most important challenges are in-band interferers, e.g., IEEE802.11a, and jitter. Because of the low-power operation of UWB receivers, with PSD of <-41.3dBm/Hz, the majority of the UWB RX’s function is based on the correlation principle, making it vulnerable to jitter. In recenet years, a new attention has been paid toward the...
Elimination of Blocker Signals in Radio Receivers Using Time-Varying Circuits
, M.Sc. Thesis Sharif University of Technology ; Fotowat Ahmadi, Ali (Supervisor)
Abstract
According to increasingly utilization of different frequency spots, RF receivers are allways under the threats of compression and desensitization because of large out-of-band or in-band blockers. The IC technologies afford fast, low-resistance switches as scaling keeps going on. With this mind, the Linear Periodic Time Varying circuits, in which the switches play the most dominant role, will be a sensible candidate for the concerns of blocker detection and rejection. Furthermore, nowadays’ receivers should be reconfigureable so as to be tunable at different frequency bands and satisfy contrastive standards. In this regard, the LPTV filters provide vast range of tunablity not only with...
Design of a Phased Array Receiver for 5G Applications
, M.Sc. Thesis Sharif University of Technology ; Sharif Bakhtiar, Mehrdad (Supervisor)
Abstract
Next-generation wireless communication requires phased-array systems to ensure Gb/s data communication. This work demonstrates a four-element phased array receiver based on N-path filters for the 5G-FR1 frequency band. The behaviour of the circuit including non-idealities and effects due to mismatch in the paths is modeled and verified via simulations. As the time-variant nature of the N-path filter introduces multiple frequency translations, third harmonic selection of the switching frequency rather than the fundamental helps to reduce the input frequency of the multiphase clock generator by a factor of three. Therefore, the proposed structure is capable of third harmonic reception as well...
An n-path enhanced-q tunable filter with reduced harmonic fold back effects
, Article IEEE Transactions on Circuits and Systems I: Regular Papers ; Volume 60, Issue 11 , 2013 , Pages 2867-2877 ; 15498328 (ISSN) ; Behmanesh, B ; Atarodi, S. M ; Sharif University of Technology
2013
Abstract
A high-Q, tunable, bandpass filtered amplifier structure is proposed which is based on a novel Q enhancement technique in N-path filters. Using Fourier series analysis, frequency response of an N-path filter as well as the aliasing effects which are present in it are derived. Frequency translation of unwanted contents at higher frequencies to the center frequency of the bandpass filter is called harmonic fold back (HFB). It is shown that using an additional N-path filter with the same clock frequency but different clock phases can reduce the HFB. The required conditions for fold back elimination are derived fromFourier series expansion analysis. In order to achieve HFB reduction as well as...
A tunable-Q 4-path bandpass filter with Gm-C second-order baseband impedances
, Article 25th Iranian Conference on Electrical Engineering, ICEE 2017, 2 May 2017 through 4 May 2017 ; 2017 , Pages 244-248 ; 9781509059638 (ISBN) ; Babamir, S. M ; Behmanesh, B ; Atarodi, S. M ; Sharif University of Technology
Abstract
An active switched-capacitor 4-path bandpass filter suitable for multi-standard applications in ultra-high frequency (UHF) band with different channel bandwidths is designed and simulated in 0.18 μm CMOS technology. The baseband impedance of the filter is implemented as a second-order Gm-C low-pass filter which can be used to tune the channel bandwidth as well as the quality factor (Q) of the RF filter. The center frequency of the filter can be tuned from 100 MHz up to 1.5 GHz by changing the clock frequency applied to the filter while its bandwidth can be tuned by tuning impedance parameters in any center frequency. To do so, the baseband impedance utilizes a frequency dependent negative...
A configurable high frequency Gm-C filter using a novel linearized Gm
, Article AEU - International Journal of Electronics and Communications ; Volume 109 , 2019 , Pages 55-66 ; 14348411 (ISSN) ; Atarodi, S. M ; Sharif University of Technology
Elsevier GmbH
2019
Abstract
A large-signal linearization method for operational transconductance amplifiers (OTA) using a combination of cross-coupled quadratic cell and a novel non-linear current injection technique is presented in this paper. Post-layout simulations show that for 180 nm CMOS process with a 1.8 V power supply, total harmonic distortion (THD) at 1.5 V peak-to-peak and 5 kHz input is less than −46 dB. Also, the dynamic range (DR) at given THD is 68 dB with power consumption of 0.64 mW. To verify the performance, the proposed OTA is used to design a new configurable filter in high-frequency range using N-path filter methodology. Universal Butterworth Gm-C active filters are embedded in the proposed...
Low power receiver with merged N-path LNA and mixer for MICS applications
, Article AEU - International Journal of Electronics and Communications ; Volume 117 , 2020 ; Safarian, A ; Sharif University of Technology
Elsevier GmbH
2020
Abstract
In this paper, a low power receiver for medical implant communication service (MICS) is presented. Low power design is vital in the MICS applications since the implanted chip has to work for a long time without the need to change its battery. As a result, a merged N-path low noise amplifier (LNA) and mixer block is proposed. In this structure, the LNA and down-conversion mixer share a transconductance to lower the overall power consumption. An N-path feedback is utilized around the shared transconductance not only to improve the LNA selectivity and relax the linearity requirements but also to downconvert the radio frequency (RF) component and create the intermediate frequency (IF) signal. In...
An N-Path filter design methodology with harmonic rejection, power reduction, foldback elimination, and spectrum shaping
, Article IEEE Transactions on Circuits and Systems I: Regular Papers ; Volume 67, Issue 12 , 2020 , Pages 4494-4506 ; Banaeikashani, A ; Behmanesh, B ; Atarodi, S. M ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2020
Abstract
In this paper, an adaptive design methodology for synthesizing a harmonic free N-path filter with reduced frequency folding is presented. System level analysis of proposed architecture shows that by adding a few extra paths with proper weights to a conventional N-path filter, several characteristics such as harmonic rejection, power reduction, foldback elimination and spectrum shaping can be achieved. The designed filter is reconfigurable to be a band-pass filter (BPF) or a band-reject filter (notch), based on the requirements. By using the nth harmonic of Local Oscillator (LO) signal, instead of the fundamental harmonic, the required input clock frequency in N-phase clock generator is...