The design considerations for fast-settling operational
amplifiers (opamps) differ significantly between sampled-data switchedcapacitor
(SC) and conventional continuous-time applications. In SC
circuits, the shape of the output voltage waveform of an opamp is of no
consequence provided that the output settles to within a specified
tolerance of its steady-state value prior...
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...
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...
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...
The chopper-stabilized operational amplifier has good low
frequency noise properties. Unfortunately a simple technique for
simulation of the chopper-stabilized operational amplifier has
not been available.
This thesis describes the implementation of a differential
amplifier using chopper stabilization and its circuit modeling
for the SPICE simulation. This circuit has been designed...
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...
Nowadays, wireless communication systems use high-order quadrature amplitude modulation (QAM) together with orthogonal frequency-division multiplexing (OFDM) to increase the link capacity and robustness. These signals always have large peak-to-average power ratio (PAPR) and require power amplifiers (PAs) achieve both high efficiency and linearity simultaneously. For the efficiency, the complementary metal...
The sensors in real time data processing IoT devices require high resolution and sub-MHz data converters, usually implemented as Incremental ADCs due to the advantages of oversampling technique and low latency. In discrete time incremental (IDT) ADCs, the sampling switch non-linearity, charge injection degrade the resolution, and power hungry OPAMPs...
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...
Sensor system plays an important role in connecting everything including human body to the electrical information systems that we have built and that we are going to build, to make the world more intelligent and efficient. One of the key propulsive forces behind these emerging techniques is CMOS scaling that...
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...
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...
This thesis will examine the model and design technique of a self-contained analog
CMOS Phase-Locked Loop. This system has an adaptable filter and demodulator for an
oscillating frequency of up to 1000 KHz and it is programmable by means of an external
resistor and capacitor. The first topic to be...
The gm/ID-based design of analog integrated circuits introduced in 1996 employs an empirical transistor sizing methodology using SPICE-generated lookup tables that enables good agreement between simulations and specifications. This thesis introduces a new SPICE lookup table that extends the gm/ID approach to the Miller pole-splitting frequency compensation of the classical...
The CMOS two-stage Operational Transconductance Amplifier (OTA) has been a key enabler for mixed-signal IC design for nearly four decades . This research focuses on a modified two-stage CMOS OTA that features load-pole cancellation (LPC); i.e., the resulting architecture is essentially a two-stage CMOS OTA with no load capacitance. The...
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...
A frequency compensation technique for increasing the
settling speed of two-stage operational amplifiers used in
switched-capacitor applications has been developed. By
properly decompressing the pole-zero doublet to form a
three-pole one zero system, the settling speed is increased
up to 50 percent as compared to the optimized two-pole
system.
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...
A MOS biquadratic (biquad) filter employing the switched-current technique is
reported. The circuit uses current-mode processing which can offer wide
bandwidth, low voltage operation, and can be implemented with standard CMOS
technology. Examples of lowpass, highpass, and bandpass filters are given
which illustrate the synthesis procedures and the versatility of...
The bandgap voltage reference technique, as implemented in Silicon technology, has evolved to a state of advanced development and become the method of choice for temperature independent voltage biasing in integrated circuits. The heterojunction bipolar transistor (HBT), fabricated from epitaxial A1GaAs /GaAs, is developing to a point where basic circuit...
A fast-settling CMOS operational amplifier using the
folded-cascode topology has been designed. The design is
based on a theory developed by Yang et al for the optimum
settling time of two-pole systems for switched-capacitor
applications. The theory states that the two poles are
separated by a given factor in order...
The ability to integrate designs from board level, multi-chip modules to single process solutions is highly attractive in today's PC multimedia industry. Saving board area and chip count will decrease the production cost of personal computing hardware and increase profitability. The ability to integrate analog circuit capability and it's reference...
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...
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...
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...
The core area of a conventional CMOS digital gate
array consists of only one size of NMOS device and one
size of PMOS device. Both primitives have fixed minimum
channel lengths, and this has significantly impeded analog
applications. This work has shown that by forming series
and parallel interconnections between...
A high-swing, high-linearity Class-AB CMOS
operational amplifier suitable for high speed
application is presented. It does not exhibit large-signal
slewing effects as do others; its output current
is limited by MOSFET aspect ratios and the total power
supply voltage. A rail-to-rail common-mode input range
is achieved by a topology which...
A circuit topology for high-swing, high-linearity
CMOS operational amplifiers has been developed. The
technique uses parallel-connected p- and n-channel
input pairs to realize an input common-mode voltage
range nearly equal to the total power supply voltage.
High linearity is achieved by summing the DC bias and
AC small-signal currents so...
In any biomedical signal acquisition system, a front-end amplifier is needed to amplify low amplitude bio-signals while filtering out any unwanted low-frequency artifacts. The design of low frequency poles within the sub-Hz range implies very large time-constants which goes against system integrability. In recent years, the pseudo resistor has been...
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 )...
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...
Deep Learning methods have been gaining a lot of significance for various Biomedical applications for diagnosing several types of diseases. Two applications considered here are: 1) Diabetic Retinopathy Detection and 2) ECG signal Classification (or Arrhythmia Detection). Diabetic Retinopathy (DR) is a major cause of blindness in Diabetic patients, and...
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...
Recently, switched-current circuits have received great
attention because they offer potentially better performance in terms
of speed, low voltage power supplies, and accuracy in mixed-mode
analog-digital signal processing. In this thesis, the distortion
characteristics, DC offset and AC gain errors induced by the threshold
voltage, channel width, channel length, and...
Analog computation in the form of neural networks is currently
receiving much attention. Existing algorithms cannot be easily
implemented in hardware because of the large number of neurons needed
and the number of connections necessary between them. These problems
have motivated development of alternatives to a conventional
implementation. Hence, a...
The output characteristics of a conventional GaAs depletion-mode MESFET device have been investigated. One of the important parameters of the small-signal GaAs MESFET model, g[subscript ds] (output conductance), is shown to be frequency and temperature dependent. Variations in g[subscript ds] are a serious problem in many analog and digital circuits...
The characteristic of the subthreshold current in a
GaAs MESFET exhibits a negative exponential function with
Vgs. After studying the behavior of this current in this
region over a range of temperature and drain bias voltages,
a subthreshold current model was developed. The model was
implemented in a circuit simulation...
A modeling technique for simulating the noise
performance of chopper-stabilized switched-capacitor
filters using SPICE2 is presented. A method for
selection of switched-capacitor network (SCN) stages
to be chopped and an op amp topology for low noise
applications are also outlined. Validity of the
modeling is verified by the close agreement...
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...
A short-circuit-protected line-driver circuit is
particularly adapted for use in a CMOS differential line-driver
system, where one line-driver circuit provides a
true output signal, and another line-driver circuit
provides a complementary false output signal. A short-circuit
is sensed by measuring current through a secondary
pull-up transistor, and disabling a primary...
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...
The operational transconductance amplifier (OTA) is a fundamental building block in analog and mixed-signal systems. This research describes a process-, voltage-, and temperature- (PVT) insensitive low-voltage tracking RC compensation scheme considered for two-stage CMOS OTAs, which cancels the pole due to the load capacitance using a Miller zero generated by...