Transcript High PSRR Input Buffer

The AQuA Converter
An Analog Memory Cell
Micah O’Halloran
Prof. Rahul Sarpeshkar
Analog VLSI & Biological Systems Group
Jan. 25, 2002
Uses of analog memory:

Circuit Offset Compensation
 Self-Tuning/Adaptive Circuits
 Learning Algorithms (Speech Processing,
Robotics)
 General Memory Element
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Two exisiting approaches to
analog storage:
 Floating-gate
transistors
 A/D/A converters
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Floating-Gate Transistors
A true analog voltage is stored on an
SiO2 isolated floating gate using hotelectron injection and tunneling.
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A/D/A – Analog-to-Digital-toAnalog Conversion
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Analog-to-Quantized-Analog (AQuA)
Converter
 No
explicit digital conversion takes
place
 Uses clock as a quantizing tool
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AQuA Operation Overview
Analog
&Step
Step
Step4 5–VLSI
–CThe
conversion
charges
3 – Step
Cuntil
is complete
V
asynchronously
is high
once
on –
awe
positive
resets
reachtoaclock
zero
positive
when
edge.
clock
the
Icaps
edge
is set and
soVthat
Vo2Viso2 high.
rises
sample
sample
o2 Step
clk voltage
c1
2
–
Begin
1
charging
Sample
Vin
both
N-1 and V
N then holds
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between the
2reaches
the
edge (N
until
is the
the number
next positive
of bitsclock
we are
edge.
quantizing to).
ref12. Itclock
Experimental Conversion
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AQuA Test Results – 6 bit
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Conclusion

The circuit was designed as a proof-ofconcept of the AQuA idea, and achieved six
bits of resolution.
 The resolution of the implemented AQuA
algorithm is very sensitive to the tuning of its
parameters.
 The design of a micropower 10-bit AQuA
using a new more robust algorithm is
currently underway.
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