Sharif Digital Repository

A Focal Plane Array (FPA) consists of one or two dimensional array of sensor elements and is widely used in imaging systems. Generally an FPA can be divided into two main parts: Sensor array and read-out/test circuit. In this thesis we design and implement a test circuit for an FPA that works in 77K. The circuit will be attached to the sensor to detect and amplify its very low level current that is in the range of 10 pA to more than 10 nA. Reducing MOSFET temperature from room temperature (300K) down to liquid nitrogen (77K) will greatly changes its parameters and characteristics such as Threshold Voltage and carrier mobility. However MOSFET models in low temperature are either... 

In this project, an inverting Buck-Boost converter with two negative linear regulator is designed, implemented and measured in CMOS 0.18μm-HV BCD technology. Input voltage of Buck-Boost converter can vary from +15V to +28 and output voltage is digitally adjustable from -1V to -10V. Maximum output current of the converter is 300mA. A current mode controller and a lag compensator is used to control the converter. A high speed highside current sensor is designed and used in current mode controller. Sampled current of the current sensor is also used in a current limit circuitary to limit the maximum current of highside switch. Two negative linear regulators are placed at the output of the... 

In this project, issues related to designing and fabricating active phase shifter blocks on the silicon substrate have been examined. Phase shifter circuits are designed in a way that have the most bandwidth and the less sensitivity to process characteristics changes and environmental conditions. The purpose of this research, is designing an active 6 bits phase shifter. The active phase shifter synthesizes the required phase using a phase interpolation process by adding quadrature phased input signals. It uses a new quadrature all-pass filter for quadrature signaling with a wide bandwidth. Also substitute structure has been suggested to this filter which is the main block in determining... 

Fully integrated frequency synthesizer is one of the important system-on-chips building blocks. Among this circuit’s remarkable applications, Bioelectronics field is very common. In these applications, advanced microelectronic circuits are used in order to diagnosis and treatment of diseases. The aim of this thesis is design and implementation a wideband frequency synthesizer in a 0.18um CMOS technology. The main usage of this circuit is in a fully integrated implantable biomedical sensory chip. This circuit generates two necessary local signals in sensory chip to stimulus cells and process the information.
Frequency synthesizer is based on phased locked loop (PLL) circuit and produce... 

In this thesis, a Ku-band (16.3-17.3) Variable Gain Amplifier (VGA) for realizing a phase array T/R module is designed, implemented and measured in CMOS 0.18μm technology. In order to achieve a maximum gain of 15dB and NF of 4.3dB and with the idea of improving the 1-dB compression point, two gain-stages and a novel inter-stage is proposed according to pre-distortion method. Applying this linearizing technique, makes it possible to get output P-1dB higher than 18dBm. Current steering technique is used for gain control mechanism. Gain tunabality range of 31.5dB is needed and this forces 6-bit operation with 0.5dB gain-step for the VGA. Because of loading effect of higher bits on the lower... 

Today, phased array antennas have important role in wireless communication systems. Utilizing optimum channel capacity, having better signal to noise ratio and, high data rate are the most important features of these systems. These systems are composed of several thousands of separated transceivers which provide possibility of directional electromagnetic radiation by changing the phase and the amplitude of the signal in each transceiver independently. So, the main components of such a system are amplifiers, phase shifters and, amplitude controllers. Also a high resolution phased array military radar system is another vital applications of these systems at frequency band of 9-10 GHz. The... 

In this thesis, a new wide band variable gain distributed amplifier (VGDA) is presented. A novel approach to implement uniform gain control in the wide band frequency range of 8 – 18 GHz is demonstrated. A different technique has been employed to provide necessary DC bias current, avoiding large DC-Feed inductors. A five-section wideband VGDA has been designed and fabricated in 0.18 μm CMOS technology. The VGDA have a flat gain of 11 dB, noise figure better than 5 dB, P1dB of 14 dBm at the output, input and output matching better than -12 dB and -14 dB, respectively, for maximum gain state over the 10 GHz UWB band. The gain control range is between 3 – 11 dB with gain steps of 0.5 dB and rms... 

In this project, a “Ku” band (16.3GHz-17.3GHz) 6-bit phase shifter for realizing a phase array T/R module is designed, implemented and measured in CMOS 0.18μm technology. Design specifications for this block were: RMS phase error should be less than 2.5 degree in bandwidth, better than 12dB loss and better than 16dBm input 1dB compression point. High-pass/low-pass filter structure is used to implement this phase shifter. In order to decrease phase shift error in process and temperature corners, a new structure for one of bits was introduced. This structure is less sensitive to process and temperature corners and furthermore it conSumes less area in layout, but it has more loss variation... 

In this study, transition metal phosphide, with a high accessible surface and abundant electroactive centers, was used as an electrocatalyst to fabrication an electrochemical sensor of Gloucose. The direct growth of thin film of nanocomposite can be considered as an efficient method to modify the electrode surface, and the application of these modified electrodes as electrochemical sensors. nanocomposite of transition metal phosphide (CuCoP) were directly grown on Cu(OH)2 nanotubes (as-prepared on GCE) in order to design hierarchical core-shell nanostructure with using efficient, inexpensive and fast method. Here, Cu(OH)2 nanotubes not only served as substrate, but also steer the CuCoP to... 

The main purpose of this Ph.D. Thesis is to develop DNA-based biosensors using Label-free approaches applying simple, inexpensive and fast electrochemical techniques to measure the biological markers of cancer.In the first part, a simple protocol for detection of specific-sequence DNA is introduced. In this method carbon nanotube is used as a hybridization indicator. This label-free system provides the advantage of eliminating additional labeling procedure. As the signal enhances in the presence of MWCNT and decreases in the presence of target, the fabricated sensor is known as a signal-off device. The oxidation signal of Fe(CN)63-/4- is followed as an analytical signal to detect target... 

In this thesis, a low-power low-phase-noise 28 GHz voltage-controlled oscillator for 5G applications is presented. At first, to select the best structure in terms of FoM, various types of inductors and transformers have been designed and EM simulated. The class-C structure which leads to the highest FoM is chosen eventually. In order to increase oscillation amplitude and reduce phase noise while preserving FoM, a high-frequency noise filter is presented. This filter which is based on a λ/8 microstrip transmission line has solved the conventional filter problems e.g. narrow bandwidth, coupling with oscillator inductor and practical implementation issues.The oscillator is designed, EM... 

Oscillators are an important building block in the design of synthesizers for RF system applications. State-of-the-art operation defines that an oscillator should have the best spectral purity while consuming a low amount of power. In recent years, several methods have been presented for reducing phase noise separately in the 1/f2 and 1/f3 regions. As CMOS technology advances, the amount of power supplies decreases, which worsens the inherent flicker noise. In this thesis, it has been tried, while investigating the existing methods in the phase noise in this region, it presents the proposed oscillator which is based on a three-coupled transformer. This voltage bias oscillator operates at a... 

The signal sources, based on CMOS technology at mm wave have two categories, the first class is a harmonic oscillator and the second class is fundamental oscillator followed by a frequency multiplier. A systematic approach to obtain the upper bound of efficiency using the activite device condition and, oscillation condition is implemented. Based on polyharmonic distortion at large signal operation, harmonic translation and efficiency are optimized. It is shown that there is an optimum phase for voltage of harmonics at the oscillator ports (the gate and the drain).Based on this analysis, a 300 GHz harmonic oscillator, simulated in TSMC 65nm CMOS is designed. The proposed oscillator has an... 

Some applications need fast locking clock and data recovery circuits for example the circuits that operate in burst mode must lock to the data packets which are transmitting from different transmitters very quickly and in just a few bit times. In such applications open-loop clock and data recovery circuits are used because lock time in closed-loop clock and data recovery circuits is usually much longer.
In this thesis a new open loop clock and data recovery circuit based on injection locking method has been proposed. This circuit can be used in applications such as passive optical networks that need fast locking. In this architecture a super harmonic injection-locked frequency divider... 

Nowadays, frequency synthesizers are widely used in many modern devices due to the ever-increasing growth of electronic circuits and their applications in various aspects of life. Imaging devices with security applications in the millimeter-wave frequency band is one of the mentioned applications. To prevent crowds at checkpoints and facilitate traffic, these devices need to monitor people's security at the highest possible speed. Furthermore, significant bandwidth is required to increase image quality. Therefore, using frequency generators with high-speed frequency sweep ability is a great advantage. In this thesis, a digital frequency generating chip with 1GHz bandwidth is designed using... 

In this study، a novel frequency multiplier chain for wideband millimeter-wave applications at 28 GHz is presented. Millimeter-wave imaging systems require high frequency and wide bandwidth to accurately detect hidden objects. Various methods have been proposed to increase the frequency of generated signals, but in the meantime، frequency multiplier structures exhibit better performance in terms of bandwidth، power consumption and, harmonic rejection. These circuits are widely used in High-frequency telecommunication systems such as 5th generation mobile services. To design a frequency quadrupler، two multiplier stages based on the improved quadrature Gilbert structure were used. Generating... 

Removing SAW filter from the input of a receiver makes the receiver extremely vulnerable to all sorts of blockers and interferers. It is shown in this thesis that due to existing large out-of-band blockers the linearity of the saw-less receiver has to be considerably higher than that of the conventional receivers with input SAW filter. These ever-present and unwanted signals that show up in the absence of the input SAW filter are divided into two groups of far and near out-of-band blockers and interferers. It is shown that removing these groups of unwanted signals require two distinct approaches, one for near and the other for the far out-of-band blockers. An inclusive solution to protect... 

Nowadays power electronic devices have a wide usage in the industries for power conditioning. As a point of view, reliability is one of the most important figure of merits that should be considered to have long life time and also have more probability to do exactly the proposed mission. One of the widely used converter topologies is DC-DC step down converter which is used in different applications such as battery charger and voltage regulator. In this project, a step down DC-DC converter with Buck topology is designed with reliability consideration. Failure rate of power components are predicted based on MIL-HDBK-217. In addition, failure rate of auxiliary components of power devices are... 

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... 

In several electro-optic and optoelectronic devices, we require the structures with simultaneous high electrical conductivity and optical transparency so as to transmit the incident light. Transparent Conductive Electrodes (TCEs) that are both highly conductive and transparent were introduced to be an answer to the mentioned challenge. Periodic arrays of metallic holes are amongst the most important structures that are used as transparent electrodes. Using the metals with low electrical resistivity, such as Au and Ag, provides these structures with high electrical conductance. On the other hand, since these micro/nano structures support the propagation of guided electromagnetic waves, light...