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.