Presented by Paul Kasemir and Eric Wilson Chapter 11 Fundamentals of Passives: Discrete, Integrated, and Embedded Presented by Paul Kasemir and Eric Wilson

Chapter Objectives Define passives and their fundamental parameters Describe the role of passives in electronic products Introduce the different forms Describe the different materials and processes used for passives

11.1 What are Passives? Can sense, monitor, transfer, attenuate, and control voltages Cannot differentiate between positive and negative polarity Cannot apply gain or amplification Passives absorb and dissipate electrical energy Ex. Resistor, inductor, capacitor, transformer, filter, switch, relay

11.2 Role of Passives in Electronic Products High frequency applications take smaller values (pF and nH) Impedance matching to coax (50 ohm) Power supplies require large capacitance Digital circuitry requires decoupling capacitors for current surges Resistors used for termination, filtering, timing and pull up/down

RF Passives Filters, couplers, RF crossings, impedance matching, and antennas. Signal inductors (1-20nH) and capacitors (1-20pF) Choke Inductors (20-100nH) Higher frequency requires smaller footprints, or even embedded passives Mixed-Signal packages used in cell phones and GPS in MCM

11.3 Fundamentals of Passives Resistor Resist current flow Dissipate a power as heat V = IR Current Density, resistivity, conductivity, and sheet resistance

Fundamentals of Capacitor Stores electrical charge Q Dielectric between 2 metal plates Capacitance C = QV = εA/d I = C(dV/dt) DC open Series and parallel capacitors Reactance, impedance, ESR, leakage current

Fundamentals of Inductor Stores energy in magnetic field Wire coil with or without core Inductance L = μn2Al V = L(dI/dt) DC short Magnetic cores increase B field, and thus inductance

Filters Low-pass High-pass Bandpass Bandstop Series-parallel combination of R, L, and C

11.4 Physical Representation

Physical Representation Discrete – single passive Integrated – multiple passives Array SIP and DIP resistor packages Network Filter circuits with only inputs and outputs as package terminals Embedded Created as part of the substrate

Passive Comparisons In a typical circuit, 80% of components are passives 50% of the PCB is taken by passives 25% of solder connections go to passives ~900 billion discrete units per year

11.5 Discrete Passives Resistors Wire-wound Film resistors Nichrome wire Film resistors Carbon or metal film deposited on substrate Carbon-composite Graphite powder, silica and a binder

Resistor applications Bias Divider Feedback Termination Pull up/down Sense Delay Timing

Polar Capacitors Aluminum electrolyte Tantalum Uneven surface gives efficiency Tantalum Pellet with lots of surface area Cathode material limits conductivity

Nonpolar Capacitors Film Ceramic High Capacitance Rolled Stacked Most dominant Like stacked film Used to need precious metals Now Ni and Cu can be used High Capacitance 1-47 F

Capacitor Performance I Remember capacitors have AC effects Temperature coefficient Typically less than 10% Some can be on order of ppm/°C Larger capacitance = worse coefficient

Capacitor Performance II Voltage coefficient Aging Logarithmic X7R 1% per decade hour (good) Reversible

Capacitors Becoming Inductors Caps have associated inductance Self resonant frequency ESL dependent on physical structure

Capacitor Applications I Coupling Timing and wave shaping Changing RC time constant Windshields

Capacitor Applications II Filtering Low pass filters Decoupling Mostly for digital signals

Inductors SMT inductors looking like SMT caps Core type Value in henries, but should also have series resistance “Choke” role Timing circuits using Ls are gone

11.6 Integrated Passives Increased quantity decreases price But maybe not as much as you would think Smaller components = higher mounting costs But maybe a lot more than you would think

Arrays and Networks Arrays Networks Many of the same type in a single package Good for R Not as much for C Networks Different types in one package Good for RC or RLC functions

11.7 Embedded (Integral) Passives Benefits Smaller Cheaper (???) More reliable Costs New designs New manufacturing processes

Integration Options Ceramic Thin film on Si IC Integration Horrible

Barriers to Embedded Passives Risk No reworkability Cost But wait until 2004!

Embedded Passives Technology R Thick film ~100-1M Ω/square Thin film ~25-100 Ω/square C Typical inorganic is 50 nF/cm2 GE has gotten ~200 nF/cm2 with inorganics Polymer-ceramic components can get 4-25 nF/cm2 L Okay in embedded if <100 nH Discrete recommended for >100 nH

The End