RFcircuitfundamentals.ppt

RF Circuit Fundamentals 張李傳 台揚科技股份有限公司 Lumped Elements Distributed Elements Lumped Elements No Variation of Characteristics Value within the Operating Frequencies, nor Variation of Signal Phase over the Element Physical Length The Physical Dimension of a Lumped Element is Relatively Small Compared to the Wavelength at the Operational Frequency. Normally, less than 1/8 Wavelength. Distributed Elements The Element Parameters R, L, and C are a Function of the Line Length and the Values of L and C Varies with Frequencies. For Example, Microstrip Lines, Coaxial Lines, Slot Lines and Coplanar Waveguides. Wire Diameters - AWG System AWG: American Wire Gauge AWG 50 = 1 mil AWG 44 = 2 x 1 mil = 2 mil AWG 38 = 2 x 2 mil = 4 mil AWG 32 = 2 x 4 mil = 8 mil AWG 26 = 2 x 8 mil = 16 mil AWG 20 = 2 x 16 mil = 32 mil Conductor Skin Depth Where d : Skin Depth, the depth into the conductor at which the current density falls to 1/e or 37% of its value along the surface w = 2p f, f : Carrier Frequency, in Hz m : Permeability, m o = 4 p x 10-7 s : Conductivity Straight Wire Inductance Where L : the Inductance in uH l : the Length of the Wire in cm d : the Diameter of the Wire in cm Air Coil Inductance Where r = the Coil Radius in cm l = the Coil Length in cm L = the inductance in microhenries Note: for Optimum Q, l = 2r Chip Inductor Chip Inductor - Q vs. Freq. Characteristics Chip Capacitor Application Notes for Ceramic Chip Capacitors- by Johansen Technology - Ceramic Chip Capacitors Exhibit Excellent Reliability Characteristics Providing That Proper Circuit Design Techniques and Controlled Assembly Processes Are Utilized. Due to the Ceramic Capacitor Crystalline Micro-structure These Components Are Susceptible When Exposed to Excessive Thermal or Mechanical Shock During Circuit Processing. It Should Be Noted That Micro-cracks in Ceramic Can Be Difficult to Detect With Normal Post Assembly Visual and Electrical Testing and Can Pose a Significant Threat to Reliable Field Operation