Introduction Fall 03
Outline Trends for Microwave Designers The Role of Passive Circuits in RF/Microwave Design Examples of Some Passive Circuits Software Laboratory Assignments Grading
Trends for Microwave Designers Wireless Communications (major market) T Trend toward integrated (very small) circuits --- transmission line theory and distributed circuits have less direct relevance (RF I is modified to account for this) T At 5 GHz.there s still a lot of board-level design that is not entirely integrated Point-to-point comm, radar and sensing T GHz through 0 GHz distributed circuits are unavoidable Broadband communications (optical telecom) T Requires microwave design at 2.5//40/80 GHz
Microwave Receiver - How Important are Passive Ckts? Some systems use multiple antennas for diversity Switch RF Filter Channel 1 Channel 2 LNA Gain Control IF Filter Channels may be multiplexed Mixer LNA Isolator Coupler Crystal Oscillator n Multiplier RF Filter
Active Components - How Important are Passive Ckts? 4-Stage 18-22 MMIC LNA Raytheon : Nominal Gain > 30 db : Noise Figure < db (@ V D = +5 V; I D = 41mA) : Technology: Raytheon 5m phemt The entire chip has only 4 active devices - the rest is passive!
0.9 1.2 Lumped Filters and Parasitics S21 1.2 0 0.9 1.2 1.8 1. 8 50 50 0. 8 1.8 0.9 S21 S43 Ideal Filter Schematic 0 - - S11 (db) -30 0 00 00 3000 4000 5000 6000 Freq (MHz) Simulated Measured 0 5 0 Loss Factor Cut-Off Frequency 5 0.00 0 00 4000 6000 Freq (MHz) Simulated Measured Inductor Radiation Effects
A 2-4 GHz Microstrip Variable Attenuator Varactor Diodes Radial Stub Chip Capacitors Microstrip Coupler
Small Discontinuities Can Be a Big Deal Parasitic reactance presented by discontinuities in transmission lines can greatly affect overall system performance (need EM simulation) 0 microns 2 micron gap TEE Junction Air Bridge
Good Designers Consider EM Effects 0 59 mil FR4 21 mil FR4 0 mil Alumina - S11 (db) - -30-40 59 21-50 0 2500 5000 7500 000 Freq (MHz) Simulated Measured Simulated Measured Simulated Measured S21 (db) -1-2 0 2500 5000 7500 000 Freq (MHz) Simulated Measured Simulated Measured Simulated Measured 21 59 Surface Mount Capacitor Coupling to Ground Effects
0.9 1.2 1.2 1.8 PWB Circuits and Modeling nf 0 0.9 1.2 1.8 4.7 nh 1.5 pf 1.5 pf 50 50 0. 8 1.8 1. 0 0.9 LNA (low noise amplifier) Bias Pad S11 Simulation Measured Data 1 6 GHz
1.2 0.9 Microwave Design for Optoelectronics 1.2 0 0. 1 0. 2 0. 3 0. 4 0. 5 0. 6 0. 7 0. 8 0. 9 1. 0 1. 2 1. 4 1. 6 1. 8 2. 0 3. 0 4. 0 5. 0 470 pf Capacitor 680 pf Capacitor Simulation Measured Data 1.8 11 GHz 50 50 1.8 0.9 Ohm Resistor 1.5 nh Inductors High frequency impedance matching network designed for laser diode 50 Ohm reference impedance; terminated in Ohm resistor (for validation)
Software Laboratories Software Laboratories are assignments that involve one or more computer-aided engineering software tools (there s no hardware involved) The topic of the labs will follow material that is discussed during the lecture Specifics about the use of the software will not be discussed in class - you will have written procedures to follow as aids The software will be available in ENB 228, and possibly in other open use labs as well
Software Laboratory Topics (Tentative) Circuit optimization and model extraction Numerical electromagnetic simulation Microstrip coupler design Lumped element filter design Distributed element filter design Microwave receiver front-end simulation
Grading - Expectations of Neatly Written Assignments All assignments are expected to be well organized and clearly legible else they will be returned with a grade of ZERO. Suggestion: if you simply cannot work well from a neatly organized piece of paper, then REWRITE your solutions before you hand them in. Don t turn in your scratch paper and expect to receive credit.