Signal Processing with Analog circuit

spectacularscarecrowAI and Robotics

Nov 17, 2013 (3 years and 9 months ago)

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SIGNAL PROCESSING WITH
ANALOG CIRCUIT

Chun Lo

Analog circuit design


Main disadvantage: low precision


Due to mismatch in analog circuit components such as
transistors, resistors and capacitors


e.g. Amplifiers: lower input signal dynamic range


Comparator: lower signal resolution



Transistors: lower accuracy in current mode DAC


Advantage:


Less power consumption


Possibly smaller area

Mismatch correction


By trimming device


Larger device, layout technique in component mismatch


Autozeroing, correlated double sampling in amplifiers


Cost of extra area, power and design complexity



By in herent programming elements


Floating gate MOSFETs



First paper


Floating Gates Transistors For Precision Analog circuit
Design: An Overview


Srinivasan, Graham and Hasler



Second paper


Analog Floating

Gate On chip Auditory Sensing
System Interfaces


Hasler, Smith, Graham, Ellis and Anderson

First paper


Structure of Floating Gate MOSFET


Programming floating gate transistors


Programming precision


Charge retention


Application examples of Floating Gate MOSFET


Differential pairs


DAC


ADC

MOSFET


MOS Transistor


Floating Gate MOSFET


The gate is completely surrounded by SiO2


No DC to ground


Used in Flash memory, ROM

Programming FG
-
MOSFET


Setting the DC voltage


Add or remove charge


Mainly two methods


Fowler Nordheim tunneling


As a global eraser for all floating gates


Hot electron injection


Program each floating gate to the desired value
individually


Programming precision


What is the smallest drain current change








A single electron change results in an accuracy of


or 12 bits

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Charge Retention


Short term drift


Observed immediately after programming


Proportional to the amount of change that is
programmed into the floating gate


Long term charge loss


Themionic emission


Related to both temperature and time

Applications


Differential pair


DAC


ADC

Second paper


Advance in analog VLSI circuits


Performance close to DSP


More option for designeer


Analog Digital Partition


Signal Processing Circuits


Noise Suppression for speech enhancement


Speech Recognition

Analog Digital Partitioning


Power and space


No overhead for tuning and programming


Work in subthreshold save power


SN VS Cost


Analog Signal Processing

Noise suppression


Main Idea: Attenuate the noise components

Speech Recognition


HMMs


States, transition probabilities and


Hidden states are words, output is audio signal
produced by speaker


Recognition problem: what is the state of the system