Post on 12-Jan-2016
Design of 3.67 GHz RF Power Amplifier
Presenters: Akshay Iyer, Logan WoodcockAdvisers: Dr. K. Koh, Yahya Mortazavi
Cognitive Radios
● Software defined radio● Programmed to run by maximizing utility of
radio frequency spectrum
Project Goal
● Design and simulate an RF power amplifier that operates between 2 and 4 GHz
● Use ADS software for design and simulation
PADigital Baseband Processor Digital to Analog Converter Modulator
Frequency Synthesizer (Oscillator)
Antenna(Tx)
Receiver(Rx)
RF Power Amplifier (PA)
● Tx side: Increases the signal amplitude to make it more easily detected
Input Matching Network Output Matching
Network
RF In
RF Out
Drain Source Voltage
MOSFET Transistor
Gate Source Voltage
Source
Load
Metal-Oxide Semiconductor Field-Effect Transistor● Creates a channel underneath the gate that
connects the source and drain terminals● Channel is created when a large enough
voltage is supplied to the gate
Smith ChartsUsed for Impedance Matching (Max Power Transfer)
Transmission Line Theory
Input Impedance
Special Cases: Open/Short Circuit Stubs
Amplifier Classes
● A, AB, B, C, Fo Phase angles
“Load Line”
“Q - Point” - DC Operating Point
DC+AC conditions:Vds=Vdd+Vac (time average of Vds must be Vdd)Vac=VoutId=Iddc+IdacIdac=-Iload=-Vout/RL
Final Schematic● Consists of two bias networks, two
impedance matching networks, and a MOSFET designed by Freescale.
Transistor and Substrate
● Freescale Model MRF8S26060H● Rogers Substrate
● Class ABo utilizes harmonics
● VDS of 50 V, VGS of 2 V
Load Line / FET Curves Results
Power Results
● Max Power Added Efficiency (PAE) of 88%
Bias Networks
● Necessary to bias the transistor to desired level
Load-Pull
● Shows impedance values specific to schematic
Impedance Matching Networks
1. Shunt2. SeriesElectrical Length (degrees)
Harmonic Balance Simulation
● Shows the effects of harmonics on output powero Increases efficiency
Scattering - Parameters
● Voltage reflection coefficientso Shows reflected voltage (return loss)
Further Steps in the Process
- Layout - EM simulation- Foundry
mwrf.com
ReferencesG. Saggio, Principles of analog electronics, Edition of book, Boca Raton: Taylor & Francis Group, 2014, p. .B. Razavi, RF microelectronics, 2nd ed., New Delhi: Dorling Kindersley India, 2012, p. 767-847.