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Type of Document Dissertation Author Liu, Qingmin URN etd-04212006-001056 Title Tunnel Diode/Transistor Integrated Circuits Degree Doctor of Philosophy Department Electrical Engineering Advisory Committee
Advisor Name Title Alan C. Seabaugh Committee Member Arpad Csurgay Committee Member Debdeep Jena Committee Member Patrick Fay Committee Member Wolfgang Porod Committee Member Keywords
- differential comparator
- frequency translation
- silicon nitride sidewall
- BCB etchback
- InP
Date of Defense 2006-04-06 Availability restricted Abstract As the minimum feature sizes in transistor technology are reached,circuit performance may also saturate. For this reason, it is
important to consider new and extraordinary ways to extend the
performance of circuits. Integrated tunnel diodes enable a variety
of design alternatives for signal processing, analog-to-digital
conversion, communications, and memory. It is the goal of this
work to analyze and explore the potential of tunnel
diode/transistor (TDT) technology for increasing speed and
reducing power dissipation beyond what can be achieved with
transistors alone.
Circuit design requires accurate device models. In this work, a
physics-based small-signal equivalent circuit model for the
resonant tunneling diode (RTD) has been developed, which unifies
previous models by Brown et al. for quantum inductance and
by Lake and Yang for quantum capacitance, and provides analytic
expressions for both the quantum inductance and quantum
capacitance. Further, two new TDT circuits: a TDT differential
comparator and a TDT frequency translator have been invented.
The TDT differential comparator is of special interest for use in
direct digital synthesis applications. Circuit simulation shows a
power dissipation of 3.5 mW/latch at 100-GHz clock frequency with
60-dBc spur-free dynamic range (SFDR) can be obtained in the TDT
comparator. In comparison with the conventional transistor
approach, power is reduced by approximately 1.6x at the same speed
and SFDR.
The TDT frequency translator is of special interest for use in
communication systems for upconverting digital signals. The
circuit consists of a transistor, a tunnel diode, and an inductor.
The transistor provides input-output isolation and power gain
relative to prior art at the expense of the immunity to the input
voltage variation.
A scalable self-aligned contact process for fabrication of the TDT
circuits has been developed using InP-based RTD and double
heterojunction bipolar transistor (DHBT). This novel approach uses
silicon nitride sidewalls and a benzocyclobutene (BCB) etchback to
form self-aligned emitter-base contacts. InP/InGaAs DHBTs have
been fabricated and the test results demonstrate the feasibility
of this sidewall and etchback process. AlAs/InGaAs/InAs RTDs were
also fabricated and demonstrated a peak current density of 1.8
mA/um^2 and a peak-to-valley current ratio of 1.8.
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