Lect2UP070_(100419)

Lect2UP070_(100419) - Lecture 070 Resistors and Inductors...

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Lecture 070 – Resistors and Inductors (4/19/10) Page 070-1 CMOS Analog Circuit Design © P.E. Allen - 2010 LECTURE 070 – RESISTORS AND INDUCTORS LECTURE ORGANIZATION Outline • Resistors • Inductors • Summary CMOS Analog Circuit Design, 2 nd Edition Reference Pages 47-48, 60-63 and new material Lecture 070 – Resistors and Inductors (4/19/10) Page 070-2 CMOS Analog Circuit Design © P.E. Allen - 2010 RESISTORS Types of Resistors Compatible with CMOS Technology 1.) Diffused and/or implanted resistors. 2.) Well resistors. 3.) Polysilicon resistors. 4.) Metal resistors.
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Lecture 070 – Resistors and Inductors (4/19/10) Page 070-3 CMOS Analog Circuit Design © P.E. Allen - 2010 Characterization of Resistors 1.) Value R = ± L A AC and DC resistance 2.) Linearity Does V = IR ? Velocity saturation of carriers 3.) Power P = VI = I 2 R 4.) Current Electromigration 5.) Parasitics 060210-01 R Cp R Cp 2 Cp 2 R L Area = A Current 050217-02 Area = A 060211-01 i v Linear Resistor Velocity saturation Breakdown Voltage Metal 050304-04 Lecture 070 – Resistors and Inductors (4/19/10) Page 070-4 CMOS Analog Circuit Design © P.E. Allen - 2010 MOS Resistors - Source/Drain Resistor 060214-02 p- substrate FOX FOX SiO 2 Metal n- well p + Older LOCOS Technology p + n -well p + STI L Tungsten Plug Intermediate Oxide Layer Tungsten Plug First Level Metal STI Diffusion: 10-100 ohms/square Absolute accuracy = ±35% Relative accuracy=2% (5 μ m), 0.2% (50 μ m) Temperature coefficient = +1500 ppm/°C Voltage coefficient ± 200 ppm/V Ion Implanted: 500-2000 ohms/square Absolute accuracy = ±15% Relative accuracy=2% (5 μ m), 0.15% (50 μ m) Temperature coefficient = +400 ppm/°C Voltage coefficient ± 800 ppm/V Comments: Parasitic capacitance to substrate is voltage dependent. Piezoresistance effects occur due to chip strain from mounting.
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Lecture 070 – Resistors and Inductors (4/19/10) Page 070-5 CMOS Analog Circuit Design © P.E. Allen - 2010 Polysilicon Resistor 30-100 ohms/square (unshielded) 100-500 ohms/square (shielded) Absolute accuracy = ±3 0% Relative accuracy = 2% (5 μ m) Temperature coefficient = 500-1000 ppm/°C Voltage coefficient ± 100 ppm/V Comments: Used for fuzzes and laser trimming Good general resistor with low parasitics Lecture 070 – Resistors and Inductors (4/19/10) Page 070-6 CMOS Analog Circuit Design © P.E. Allen - 2010 N-well Resistor p - substrate FOX FOX Metal n - well n + FOX n -well n + n + L Tungsten Plug Intermediate Oxide Layer Tungsten Plug First Level Metal STI STI p -substrate L 060214-04 LOCOS Technology 1000-5000 ohms/square Absolute accuracy = ±40% Relative accuracy ± 5% Temperature coefficient = 4000 ppm/°C Voltage coefficient is large ± 8000 ppm/V Comments: Good when large values of resistance are needed. Parasitics are large and resistance is voltage dependent Could put a p + diffusion into the well to form a pinched resistor
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Lecture 070 – Resistors and Inductors (4/19/10) Page 070-7 CMOS Analog Circuit Design © P.E. Allen - 2010 Metal as a Resistor Illustration: Resistance from A to B = Resistance of segments L 1 , L 2 , L 3 , L 4 , and L 5 with some correction subtracted because of corners.
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Lect2UP070_(100419) - Lecture 070 Resistors and Inductors...

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