Design of 3.67 GHz RF
Power Amplifier
Presenters: Akshay Iyer, Logan Woodcock
Advisers: Dr. K. Koh, Yahya Mortazavi
Cognitive Radios
● Software defined radio
● Programmed to run by maximizing utility of
radio frequency spectrum
Project Goal
Digital Baseband
Processor
Digital to Analog
Converter
Modulator
Frequency
Synthesizer
(Oscillator)
PA
● Design and simulate an RF power amplifier
that operates between 2 and 4 GHz
● Use ADS software for design and simulation
Antenna
(Tx)
Receiver
(Rx)
RF Power Amplifier (PA)
● Tx side: Increases the signal amplitude to
make it more easily detected
Gate Source
Voltage
Source
RF In
Input Matching
Network
Drain Source
Voltage
MOSFET
Transistor
Output Matching
Network
RF Out
Load
Metal-Oxide Semiconductor FieldEffect 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 Charts
Used for Impedance Matching
(Max Power Transfer)
Transmission Line Theory
Input Impedance
Special Cases: Open/Short Circuit Stubs
Amplifier Classes
● A, AB, B, C, F
o
Phase angles
“Load Line”
“Q - Point” - DC Operating Point
DC+AC conditions:
Vds=Vdd+Vac
(time average of Vds
must be Vdd)
Vac=Vout
Id=Iddc+Idac
Idac=-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
Load Line / FET Curves Results
● Class AB
o
utilizes harmonics
● VDS of 50 V, VGS of 2 V
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. Shunt
2. Series
Electrical Length (degrees)
Harmonic Balance Simulation
● Shows the effects of harmonics on output
power
o
Increases efficiency
Scattering - Parameters
● Voltage reflection coefficients
o
Shows reflected voltage (return loss)
Further Steps in the Process
- Layout
- EM simulation
- Foundry
mwrf.com
References
G. 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.