Sharif Digital Repository

In this thesis, we try to design and implement a low noise, low power consumption CMOS direct conversion mixer with LO-2LO topology. Direct conversion mixers have two differential I,Q outputs. Because of zero intermediate frequency, flicker noise is critical. This mixer is designed for UHF band in TSMC CMOS 0.18µm technology. Total current consumption of I,Q mixer is less than 3mA .Voltage conversion gain is about 23 dB and DSB noise figure is less than 3.5 dB. Some conventional thermal and flicker noise cancellation has been used simultaneously to reduce noise figure. New noise cancellation techniques are proposed to get further improvement in noise figure with negligible extra current... 

Nowdays, Navigation sattelite systems are playing critial role in human life. In many equipments such as cell phone, transmitters , transportation systems ,etc. Accurate and reliable navigation is needed.
GPS was the first navigation sattelite system but today rival nations have delevoped or are developing parallel systems. These systems are Glonass operated by Russisa, Galileo by Europe and Beidou By china. GPS can not suffice human needs alone so the proposed solution is to exploit all above mentioned altenative systems. In this case, we can achieve higher accuracy, lower navigation time and more reliable navigation.
In this thesis the receiver is designed to receive all above... 

Dish-stirling system with an efficiency of nearly 30% is the most efficient technology among solar energy technologies. This system includes four main parts; Parabolic dish, solar tracker, receiver and Stirling engine and generator. In this system, first parabolic dish concentrates sun rays on its focus. A receiver is put on the focus to receive the heat radiated from dish. This receiver transfers the heat to a Stirling engine. In Stirling engine, expansion and contraction of gas helps piston to move and finally rotational mechanical work is done. With coupling a generator and Stirling engine we can generate electricity. Also for keeping the focus of sun rays on receiver we should have sun... 

This thesis begins in an attempt to design an X band front-end receiver in GaAs pHEMT technology, suitable for microwave circuits which should be high frequency, low noise, high gain, as well as high power handling and should have stable characteristics at large number of productions. The front-end receiver consists of three blocks, namely limiter, low noise amplifier, and mixer, which are designed in ISDL group previously. The measurement result of the fabricated low noise amplifier was satisfactory, since it was close to its simulation result. However, due to the drawbacks of modeling the switching behavior of devices, the results of the two other blocks, i.e., limiter and mixer – which... 

Imaging using ultrasonic waves is one of the common non-invasive diagnostic methods which have gained a lot of attention in recent years. The imaging resolution depends mainly on the center frequency of the ultrasonic transducer. High frequency ultrasonic imaging is mainly used in intravascular, skin and eye diseases and also in small animal studies. The main Goal of this thesis is to design two high frequency ultrasound imaging probes (between 10 to 50 MHz) which millimetric dimensions which can be used to image skin, eye or intravascular systems. In this thesis after discussing the science of high frequency ultrasound and reviewing the importance papers and books on the subject, two... 

Design of a 28GHz phased array receiver front-end for 5G applications in CMOS 0.18um technology in the frequency band from 27.5 to 28.3 GHz is presented in this thesis. We use an RF phase shifting structure which consists of a low-noise amplifier, a phase shifter and a power combiner. The low-noise amplifier is designed using common-source cascode topology with a transformer-based gm-boosting technique in order to enhance the power gain and reduce the noise figure. A vector sum phase shifter is then designed to further enhance the gain. A Wilkinson power combiner with lumped elements is designed as the power combiner. The results of simulating a single RX chain shows a maximum of 15 dB... 

The most important feature of the fifth generation of mobile telecommunications is the increase of information transfer rate and together with it the increase of the capacity of telecommunication channels in comparison with the previous generation. One solution is to increase the frequency toward millimeter-wave frequencies. Currently, the most suitable option for the millimeter-wave frequency band is the 28 GHz band, which has received a lot of attention due to its availability and the possibility of implementing cheap integrated circuits using CMOS technology in this band. In addition to the features that this frequency band has; This band has limitations such as high emission losses and... 

In data transmission from a transmitter to a receiver, in some applications receiving updated data is crucial. To this end, a metric called Peak Age of Information has been introduced, the minimum of which is equivalent to having more updated packets. In this thesis, a method for calculating the probability distribution function of this random variable in a random access network with a transmitter, a relay, and a receiver in which the error probability of the channels between the transmitter and the relay and also the relay and the receiver is less than the error probability of the channel between the transmitter and the receiver, is proposed. The transmitter and the relay send their packets... 

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...