INF5470 Fall 2011 Lecture 1: Basic Analog CMOS NFET symbol and - PowerPoint PPT Presentation

INF5470 — Fall 2011 Lecture 1: Basic Analog CMOS

NFET symbol and cross section � � � � � � � � � � � � � � �� �� �� �� �� �� �� � � Lecture 1: Basic Analog CMOS 2

NFET formulae I DS = I F − I R � VG − VT 0 − nVS(D) � I F(R) = I S ln 2 1 + e 2 nUT In saturation: I F >> I R Triode region/linear region: I F ≈ I R Lecture 1: Basic Analog CMOS 3

NFET characteristics I D vs. V DS −5 4x 10 3.5 3 2.5 I D 2 1.5 1 0.5 0 0 1 2 3 4 5 V DS Lecture 1: Basic Analog CMOS 4

NFET Formulae Simplified in Weak Inversion Weak inversion/subthreshold: (I F << I S ) = (V G < V T 0 + nV S ) NFET equation simplifies to: VG − VT 0 − nVS I F = I S e nUT Lecture 1: Basic Analog CMOS 5

NFET Formulae Simplified in Strong Inversion Strong inversion/above threshold: (I F >> I S ) = (V G > V T 0 + nV S ) simplifies to: � 2 I F(R) = I S � V G − V T 0 − nV S(D) 4 nU T Lecture 1: Basic Analog CMOS 6

NFET Early effect V D + V Early I F = I F V Early Lecture 1: Basic Analog CMOS 7

NFET characteristics I D vs V GS −4 6x 10 0 10 5 4 −10 10 log I D I D 3 2 −20 10 1 −30 0 10 0 1 2 3 4 5 0 1 2 3 4 5 V GS V GS Lecture 1: Basic Analog CMOS 8

Briefly Mentioned: Gate Leakeage/Direct Tunneling t ox ≤ 2 − 3nm  � 2   � 1 − Voxqe 3  B  1 −    φox     −  A V 2 Vox  if V ox < φ ox ox e ox J g = tox (1) t 2 q e  B   − A V 2 Vox  if V ox > φ ox  ox e ox tox   t 2 q e Lecture 1: Basic Analog CMOS 9

Capacitor Symbol and Cross Section Lecture 1: Basic Analog CMOS 10

Capacitor formulae V = 1 C Q δV δt = 1 C I Lecture 1: Basic Analog CMOS 11

Resistor Layout ����������� �� �� Lecture 1: Basic Analog CMOS 12

Resistor Formula V = RI Lecture 1: Basic Analog CMOS 13

Current Mirror Schematics � � �� ��� Lecture 1: Basic Analog CMOS 14

Current Mirror formulae I out = I in (if both transistors are in saturation, and have the same W/L ratio, and neglecting the Early effect) Lecture 1: Basic Analog CMOS 15

Differential Pair Schematics � � � � � � � � ���� Lecture 1: Basic Analog CMOS 16

Differential Pair Formulae − VT 0 − VC V 1 V 2 � � I b = I 1 + I 2 = I S e nUT e nUT + e nUT V 1 − V 2 I 1 I 1 I b − I 1 = e nUT I 2 = Lecture 1: Basic Analog CMOS 17

Transconductance Amplifier Schematics � � � � ��� � � ��� � � ��� ���� � ��� � ��� � � � � ���� Lecture 1: Basic Analog CMOS 18

Transconductance Amplifier Formulae V + V − nUT − e nUT e = I b tanh V + − V − I out = I b V + V − 2 nU T nUT + e nUT e Lecture 1: Basic Analog CMOS 19

Resistive Net Lecture 1: Basic Analog CMOS 20

Resistive Net Formulae δ 2 V V R V = δx 2 δy 2 R H Lecture 1: Basic Analog CMOS 21

Diffuser Net � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � Lecture 1: Basic Analog CMOS 22

Diffuser Net Formulae δ 2 V ∗ V ∗ V = R ∗ δx 2 δy 2 R ∗ H − V V ∗ = − e UT VG − VT 0 1 R ∗ = g ∗ = I S e nUT Attention: transistors must be in subthreshold for this to be applicable! Lecture 1: Basic Analog CMOS 23

Winner Take All (WTA) Principle � � � � � � � � + + + + + + + + - - - - + + + + � � � � � � � � Lecture 1: Basic Analog CMOS 24

WTA Basic Circuit � ��� � �� � ��� � �� � ��� � �� � ���� Lecture 1: Basic Analog CMOS 25

Smooth Cooperative/Cross Exitation WTA � �� � �� � �� � � � � � � � ��� � ��� � ��� � ���� Lecture 1: Basic Analog CMOS 26

Hysteretic WTA ��� ��� ��� ��� ��� ��� � ��� � ��� � ��� � �� � �� � �� � ���� Lecture 1: Basic Analog CMOS 27

Local/Cross Inhibition WTA � ��� � �� � ��� � �� � ��� � �� � � � � � � � ���� � ���� � ���� Lecture 1: Basic Analog CMOS 28

Weekly Task Propose a circuit that computes: I out = 2 I in Y out = C 1 log C 2 X in (X in and Y out may both be either I or V ) Lecture 1: Basic Analog CMOS 29