The Art And Science Of Analog Circuit Design (edn Series For Design Engineers)

The Art and Science of Analog Circuit Design The EDN Series for Design Engineers J. Williams J. Lenk V. Lakshminarayanan J. Lenk M. Brown B. Travis and I. Hickman J. Dostal T. Williams R. Marston N. Dye and H. Granberg Gates Energy Products T. Williams J. Williams R. Pease I. Hickman R. Marston R. Marston I. Sinclair The Art and Science of Analog Circuit Design Simplified Design of Switching Power Supplies Electronic Circuit Design Ideas Simplified Design of Linear Power Supplies Power Supply Cookbook EDN Designer's Companion Operational Amplifiers, Second Edition Circuit Designer's Companion Electronics Circuits Pocket Book: Passive and Discrete Circuits (Vol. 2) Radio Frequency Transistors: Principles and Practical Applications Rechargeable Batteries: Applications Handbook EMC for Product Designers Analog Circuit Design: Art, Science, and Personalities Troubleshooting Analog Circuits Electronic Circuits, Systems and Standards Electronic Circuits Pocket Book: Linear ICs (Vol. 1) Integrated Circuit and Waveform Generator Handbook Passive Components: A User's Guide The Art and Science of An3iOQ Circuit Design H ^R • • ^|MB H ^9^r '^B^l Edited by Jim Williams Butterworth-Heinemann Boston Oxford Melbourne Singapore Toronto Munich New Delhi Tokyo Newnes is an imprint of Butterworth-Heinemann. Copyright © 1998 by Butterworth-Heinemann "\lSJ\J\j I ; P re-amp Load _^ ; I > 1MO \ IVf»4 <> ^ 4 "S 70 \ IK ' *— 7 \ ^ : C L 2pF_._ L SRL10KQ i J -but Steve Roach P Drain c gd Gate r u gs ds=1/9ds =770Q T 0.4pF rs=1/gm=67a 2.9pF ° Source Figure 7-5. A linear model of a BSD22, a typical high-frequency, short-channel MOSFET. The gate current is zero at DC because the controlled current source keeps the drain current equal to the source current. In oscilloscope circuits I often remove the ground plane in small patches beneath the components to reduce the capacitances. One must be extremely careful when removing the ground plane beneath a high-speed circuit, because it always increases parasitic inductance. I once turned a beautiful 2GrHz amplifier into a 400MHz bookend by deleting the ground plane and thereby effectively placing large inductors in the circuit. Drain \ lead 0.5 nH Gate Substrate pad ,0.12 pF 3.Omm ! Source inter-lead capacitance ±1 O.O4 pF Drain bond wire 0.5 nH inter-lead capacitance I 0.04 pF SOT-143 Package Gate o- lead 0.5 nH T I bond wire O.5nH pad 0.12pF Substrate inter-lead capacitance 0.04 pF bond wirej 0.5 nH inter-lead' capacitance 0.04 pF lead 0.5 nH pad 0.12 nH Source Figure 7-6. A MOSFET with SOT-14