Digitally-programmable filters have been an ongoing research topic for a number of years. The first such filters were FIR transversal filters using Charge-Coupled Devices (CCD's) and IIR recursive filters using switched-capacitor (SC) techniques. Although both techniques achieve excellent results, they require non-standard and/or additional IC fabrication steps. Low substrate doping...
It has become customary in electrical engineering to think of
signal processing in terms of voltage variables to the exclusion of
current variables. This tendency has resulted in voltage signal
processing circuits such as voltage-controlled voltage sources
(VCVS) and voltage-mode operational amplifiers. However, the VCVS
operational amplifier has several limitations...
With increasing interest in current-mode analogue processing due to its high
performance properties such as speed, bandwidth and accuracy compared to voltage-mode
processing, new current-mode alternatives to various conventional circuit designs are
appearing. In this report, a novel circuit design to construct a fully-differential current-mode
operational amplifier ( OP-AMP )...
In this dissertation, two important current mode circuit design subjects have
been explored. In the first part, the switched-current circuit technique has been
investigated. The fundamental performance and limitations of this technique are
explored. One of the major limitations, the signal distortion caused by clock
feedthrough has been substantially reduced...
In this paper, an analysis of the clock-feedthrough effects in
switched-current (SI)' circuits will be presented. The clock-feedthrough
effects caused by the non-ideal characteristic of MOS
switches when they are turned off limit the accuracy of the analog
track-and-hold (T/H) circuits. A model to analyze and characterize this
effect is...
The design and implementation of Switched-Current (SI) ladder filters is
described. SI filters require only a standard digital CMOS process and the power
supply voltage requirement is low. SI circuits also can be potentially operated at
higher frequencies than Switched-Capacitor (SC) filters due to the low-impedance
wideband nodes of the...
Clock-feedthrough effects, channel-length modulation and device mismatch are
the main causes of the inaccuracy of Switched-Current (SI) circuits. In this paper, these
non-ideal effects are analyzed. A high-performance current mirror, namely regulated
cascode current mirror, which eliminates drain voltage variation problem is introduced.
By using this current mirror as a...
The semiconductor gallium arsenide (GaAs) has many potential
advantages over the more widely used semiconductor silicon (Si).
These include higher low field mobility, semi-insulating substrates,
a direct band-gap, and greater radiation hardness. All these
advantages offer distinct opportunities for implementation of new
circuit functions or extension of the operating conditions...
Decision feedback equalizer (DFE) is an effective method to remove inter-symbol
interference (ISI) from a disk-drive read channel. Analog IC implementations of DFE
potentially offers higher speed, smaller die area, and lower power consumption when
compared to their digital counterparts.
Most of the available DFE equalizers were realized by using...
Multi-level decision feedback equalization (MDFE) is an effective technique to remove inter-symbol interference (ISI) from disk readback signals, which uses the simple architecture of decision feedback equalization. Parallelism which doubles the symbol rate can be realized by setting the first tap of the feedback filter to zero.
A mixed-signal implementation...
Multi-level decision feedback equalization (MDFE) is an effective sampled signal processing technique to remove inter-symbol interference (ISI) from disk read-back signals. Parallelism which doubles the symbol rate can be realized by utilizing the characteristic of channel response and decision feedback equalization algorithm.
A mixed-signal IC implementation has been chosen for...
The integration of photodetectors with IC circuits provides a significant
improvement over conventional designs. Featuring noise reduction, extended frequency
responses, lower power consumption, and data operations, these integrated devices open
challenging opportunities for many applications. One type of photodetector has the
potential for important applications in the life science and...
Pulse Width Modulation (PWM) has been used extensively for motor control, DC-AC
converters, DC-DC converters and in audio applications. The conventional method of
generating a pulse width modulated signal involves generating an accurate sawtooth or triangle
wave using analog circuits. In CMOS, being analog circuit intensive puts extra constraints
on...
As Si MOS approaches its maximum limits in speed and bandwidth, new
devices are desired to meet the needs of high speed communications and signal
processing. A device that exhibits superior performance to Si MOS, BJT, and
GaAs technology is the HEMT (high electron mobility transistor).
The HEMT offers superior...
Advancements in the sophistication and complexity of modern electronic systems are creating a need for highly integrated systems with ever higher operational frequencies. The economical demands of these systems dictate that they be implemented using low cost fabrication technologies, such as digital CMOS. One of the major challenges facing circuit...
In recent years, there has been an extensive effort to develop low-cost implementations
of radio frequency integrated circuits for consumer applications. This thesis is a
research effort in the design and implementation of integrated RF CMOS Power Amplifiers
(PAs). A significant challenge in the implementation of RF CMOS ICs is...
Full integration of CMOS low noise amplifiers (LNA) presents a challenge for low
cost CMOS receiver systems. A critical problem faced in the design of an RF CMOS LNA
is the inaccurate high-frequency noise model of the MOSFET implemented in circuit
simulators such as SPICE. Silicon-based monolithic inductors are another...