射频关键性设计教程Lecture08_.pptVIP

Lecture 8 Richard Li, 2009 * 1. Equipotentiality on the Grounded Surface o Equipotentiality on the Grounded Surface of a RF cable o Equipotentiality on the Grounded Surface of a PCB o Possible Problems of a Large Test PCB o Coercing Grounding o Testing for Equipotentiality 2. Forward and Return Current Coupling o “Indifferent Assumption” and the “Great Ignore” o Reduction of Current Coupling on a PCB o Reduction of Current Coupling in a IC Die o Reduction of Current Coupling between Multiple RF Blocks o A Plausible System Assembly 3. PCB and IC Chip with Multi Metallic Layers Appendixes A.1 Primary Considerations of a PCB Lecture 8 : Equipotentiality and Current Coupling ? Richard Chi-Hsi Li 李缉熙 Cellular phone: (PRC) Email : chihsili@ 1. Equipotentiality on the Ground Surface o Equipotentiality on the Ground Surface of a RF Cable G1 Figure 1 A regular RF cable G2 RF cable Ga Gb ? ? ? Questions Answers In most cases, In most cases, In most cases, o Equipotentiality on the Ground Surface of a PCB Vdd or Vcc Top metallic area Bottom metallic area Figure 2 Discussion of equipotentiality between points, A, B, C, D, E, F (The printed circuit on the PCB is neglected) 50 Ω runner Conductive via from top to bottom “Zero” Capacitor Out PC B In A B C D E F ? Questions Answers In most cases, o Possible Problems of a Large Test PCB Figure 3 An example of test setup with a large PCB Top metallic area; GG : Ground of signal generator Bottom metallic area; GS : Ground of spectrum analyzer Conductive via from top to bottom; GP : Ground of DC power supply “Zero” capacitor; A, B, C, D, E, F, G : SMA connector; Expected Ground points on PCB. DC Power Supply Signal Generator Spectrum Analyzer Vdd