367 research outputs found

    Analysis of Internally Bandlimited Multistage Cubic-Term Generators for RF Receivers

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    Adaptive feedforward error cancellation applied to correct distortion arising from third-order nonlinearities in RF receivers requires low-noise low-power reference cubic nonidealities. Multistage cubic-term generators utilizing cascaded nonlinear operations are ideal in this regard, but the frequency response of the interstage circuitry can introduce errors into the cubing operation. In this paper, an overview of the use of cubic-term generators in receivers relative to other applications is presented. An interstage frequency response plan is presented for a receiver cubic-term generator and is shown to function for arbitrary three-signal third-order intermodulation generation. The noise of such circuits is also considered and is shown to depend on the total incoming signal power across a particular frequency band. Finally, the effects of the interstage group delay are quantified in the context of a relevant communication standard requirement

    Investigation of charge coupled device correlation techniques

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    Analog Charge Transfer Devices (CTD's) offer unique advantages to signal processing systems, which often have large development costs, making it desirable to define those devices which can be developed for general system's use. Such devices are best identified and developed early to give system's designers some interchangeable subsystem blocks, not requiring additional individual development for each new signal processing system. The objective of this work is to describe a discrete analog signal processing device with a reasonably broad system use and to implement its design, fabrication, and testing

    Fifth-order Polynomial Predistortion for Mach-Zehnder Modulator Linearization

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    Modern wireless applications require access to ultra-wide instantaneous RF bandwidths to provide frequency agility and multi-band RF processing. Wireless communications, radar and electronic warfare are examples of applications that will benefit from wideband multi-function transceivers. The role of the front-end filtering is critical in order for the multi-function transceiver to achieve adequate RF performance. Integrated electric filters are unable to achieve the required frequency selectivity and tuning range mainly due to low Q of on-chip inductors. This renders a complete integrated solution impractical. Normally, high frequency and high selectivity filters are achieved with off-chip bulky SAW filters. The limitation of electrical filters has motivated the employment of RF photonic receivers. The main issue with photonics is the cost but in recent times the emergence of silicon photonics has enabled the potential of RF photonics receivers to be implemented at a low cost. The use of photonics gives access to devices that can achieve really high Q and high integration at high frequencies. At the heart of the photonic receiver is the Mach-Zehnder modulator (MZM). It modulates the received signal from the antenna to the optical carrier. The major issue with the MZM is: it is non-linear and wideband. The MZM is placed before the photonic filter and right after the antennae so interferers received with the desired RF signal generate intermodulation products at the output of the MZM. The intermodulation products can be very close to the desired RF signal so they cannot be filtered out by the photonic filter and may corrupt the desired RF signal. To curtail the effects of the MZM non-linearity, linearization schemes are implemented to reduce the amplitude of the intermodulation products generated when the MZM receives interferers. This thesis work focuses on two main issues, Firstly, analysis of the intermodulation products generated by the MZM when a two tone RF signal is applied. Secondly, a literature review is done to examine the existing linearization schemes. Based on the predistortion linearization scheme, a new fifth-order predistortion is proposed. The proposed fifth-order predistortion is fabricated in GP 65nm TSMC CMOS process. The proposed fifth-order linearization achieves high IM3 suppression~ 20dB at high modulation index ~49.7% with 49.2mW of power consumed

    Design of CMOS Current-Mode Analog Computational Circuits

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    High Temperature Silicon Carbide Mixed-signal Circuits for Integrated Control and Data Acquisition

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    Wide bandgap semiconductor materials such as gallium nitride (GaN) and silicon carbide have grown in popularity as a substrate for power devices for high temperature and high voltage applications over the last two decades. Recent research has been focused on the design of integrated circuits for protection and control in these wide bandgap materials. The ICs developed in SiC and GaN can not only complement the power devices in high voltage and high frequency applications, but can also be used for standalone high temperature control and data acquisition circuitry. This dissertation work aims to explore the possibilities in high temperature and wide bandgap circuit design by developing a host of mixed-signal circuits that can be used for control and data acquisition. These include a family of current-mode signal processing circuits, general purpose amplifiers and comparators, and 8-bit data converters. The signal processing circuits along with amplifiers and comparators are then used to develop an integrated mixed-signal controller for a DC-DC flyback converter in a microinverter application. The 8-bit SAR ADC and the 8-bit R-2R ladder DAC open up the possibility of a remote data acquisition and control system in high temperature environments. The circuits and systems presented here offer a gateway to great opportunities in high temperature and power electronics ICs in SiC

    Design of CMOS Current-Mode Analog Computational Circuits

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    High Linearity Broadband RF Vector Multiplier for Analog/RF Pre-distortion

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    Wireless communication systems are moving towards a heterogeneous solution, where small-cell base stations such as pico-cells and femto-cells are used concurrently with macro- cell base stations in high data traffic areas. Small-cell networks are expected to provide much larger wireless data rates and capacity in small areas while only consuming a fraction of the power. However, power amplifier nonlinearity does not scale down with the size of the base station; a similar degree of nonlinearity correction is required in both small-cell and macro-cell base stations, meaning that the power consumed by the signal linearization circuits is the same. An analog-radio frequency pre-distortion (ARF-PD) solution, operating at a fraction of a conventional digital pre-distortion's power consumption, has been proposed to support the unrestrained growth of wireless communication. This thesis forms part of an ongoing research project aimed at developing a fully integrated ARF-PD solution - a promising, low-power alternative to digital pre-distortion for future wireless communications. Specifically, it focuses on delivering an integrated design of a low-power high-linearity broadband radio frequency (RF) vector multiplier, which can be used as part of the ARF-PD solution. An RF vector multiplier is considered one of the major function blocks in analog pre-distortion solutions, as it allows the analog pre-distorter to interface with the undistorted signal in the RF domain. In the thesis, two RF vector multiplier designs are proposed and implemented in integrated circuits. In the first implementation, the RF vector multiplier is designed to directly apply pre-distortion to the RF signal. This architecture imposes a need for high gain in the RF vector multiplier, which results in large transistor size and high power consumption in the output stage. The design is able to achieve promising simulation results, however, performance limitations and disadvantages are also clearly exposed compared to commercial products. To resolve the issues discovered, an alternative ARF-PD architecture is adopted to relax the output power level needed from the RF vector multiplier. In addition, a self-linearized variable gain amplifier topology is proposed to improve system linearity. Overall, the second design shows significant improvement in bandwidth, linearity and output noise level, while only consuming half of the power consumed by the first design. Ultimately, simulation results have shown satisfying performance for both RF vector multipliers as part of an ARF-PD system. However, both of the proposed integrated circuit designs should be validated by measurement

    Integrated chaos generators

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    This paper surveys the different design issues, from mathematical model to silicon, involved on the design of integrated circuits for the generation of chaotic behavior.Comisión Interministerial de Ciencia y Tecnología 1FD97-1611(TIC)European Commission ESPRIT 3110

    Design of low power CMOS UWB transceiver ICs

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    Master'sMASTER OF ENGINEERIN
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