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Low Noise Amplifiers
EERF6395
RF/Microwave Systems Engineering
Dr. R. E. Lehmann
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Applications Receivers
Communications
Radio
Cell phone
WLANs, Bluetooth
Radar militar commercial
Narrowband Complements the transmitter as a T/R function
Electronic warfare
Wideband receivers
Channelized receivers Radio astronomy
Cryogenically cooled receivers
Very narrow bandwidths
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Inside a Cell Phone
Source: http://electronics.howstuffworks.com/inside-cell-phone.htm
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Transmit/Receive Module(T/R Module)
Driver Amp Power Amp
Phase
Shifter
LNA LimiterSwitch
Antenna
Circulator
Tx
Rx
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X-band T/R Module
Source: http://www.microwaves101.com/encyclopedia/transmitreceivemodules.cfm
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Radio Astronomy
The Goldstone Radio Telescope:
Located at the Goldstone Deep Space
Communications Complex in the Mojave Desert,
near Barstow, California.
diameter, is nine stories high, and weighs 850,000pounds.
Known as Deep Space Station 12 (DSS-12), the
antenna was used by NASA's Deep Space
Network to track robotic planetary missions such
as the Mariner missions, Voyagers 1 and 2,Galileo, and other spacecraft exploring the Solar
System.
Source: http://deepspace.jpl.nasa.gov/dsn/gavrt/index.html
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Arecibo ObservatoryThe Arecibo Radio Telescope:
Located in Arecibo, Puerto Rico
Its position near the equator allows viewing of
all the planets in our solar system
Diameter = 305m (1000 ft)
s e arges s ng e re ec or e escope n e
world.
Spherical reflector (not parabolic) to reduce
astigmatism when the receiver is in different
positions off the focal point. (The error of a
spherical reflector is the same in every
direction.)
Can transmit EIRP of 20TW at 2.38 GHz
Source: http://en.wikipedia.org/wiki/Arecibo_Observatory
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Univ. of Illinois Radio Telescope
Source: http://www.ece.illinois.edu/about/history/reminiscence/400ft.html
Professor H. D. Webb used this telescope from 1959-1969 to map a large portion
of the Milky Way galaxy.
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Cryogenically Cooled Receivers
Receivers are cooled to ~15K using liquid
helium
Special considerations must be given to
low temperatures.
Special packaging and assembly must be
considered to prevent damage due to thelarge temperature change.
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Low Noise Device Technology Semiconductor material
Silicon (Si) Silicon Germanium (SiGe)
Gallium Arsenide (GaAs)
Indium Phos hide InP
Devices Field Effect Transistor (FET)
Bipolar Junction Transistor (BJT)
Heterojunction Bipolar Transistor (HBT)
High Electron Mobility Transistor (HEMT) Pseudomorphic HEMT (pHEMT)
Metamorphic HEMT (mHEMT)
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Low Noise AmplifierSimplified Single-ended Design
Input
Matching
Network
Interstage
Matching
Network
Output
Matching
Network
S S * SS S * S S *
First stage is designed for minimum noise figure.
Input matching network is designed to present the optimum noise match, opt,
to the first stage transistor.
Note: opt is NOT = to S11*
Second stage is designed for a combination of:a) Maximum gain
b) Maximum output return loss
c) Flat gain response across frequency
d) Maximum TOI
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Balanced Amplifier
Input 50- Load
Output50- Load
3-dB
Coupler
3-dB
Coupler
Advantages:
Excellent I/O return loss
Approx. 3dB more Pout & OIP3
Less sensitivity to source & load
Disadvantages:
Large size compared to single-ended
Twice as much DC power required
Higher cost
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Balanced LNA NF
Input 50- Load
Output50- Load
3-dB
Coupler
3-dB
Coupler
Gain (dB) -0.5 20 -0.5
F (dB) 0.5 1.5 0.5
Po (dBm) 13 15.5
OIP3 (dBm) 23 25.5
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Balanced NF Calculation For balanced noise figure calculations, the
balanced topology can be treated as asingle-ended cascade:
Input
Coupler
Output
Coupler
Gain (dB) -0.5 20 -0.5
F (dB) 0.5 1.5 0.5
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Balanced NF Calculation
GG
F
G
F
FFtot
)112.1()141.1(
)1()1(
21
3
1
2
1
+
+=
dBF
F
F
tot
tot
tot
tot
0.258.1
0013.046.012.1
)100)(89.0(89.0.
=
=
++=
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LNA Biasing+V
(drain supply)
+V
(drain supply)
-V
(gate supply)
Dual-bias configuration:
More precise bias conditions
Easier to adjust for optimal performance Requires two independent supplies
Self-bias configuration:
Single supply
Often difficult to adjust current Lower cost to implement in system
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http://www.triquint.com/prodserv/more_info/proddisp.aspx?prod_id=TGA2511
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TriQuint TGA2511 LNA
http://www.triquint.com/prodserv/more_info/proddisp.aspx?prod_id=TGA2511
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TGA2511 LNA Specifications
(Dual-supply bias)
Parameter Typical Worst Case Units
Frequency range 6 14 6 - 14 GHz
Drain voltage, Vd 5.0 5.0 V
Drain current, Id 160 160 mA
Small-signal gain, S21 20 19 dB
Input return loss, S11 18 16 dB
Output return loss, S22 18 14 dB
Noise figure 1.3 1.7 dB
Output power @ 1dB comp., P1dB 12 10 dBm
OIP3 (TOI ref. to output) 24 21 dBm
[Source: www.triquint.com]
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TGA2511 LNA
Gain Performance
http://www.triquint.com/prodserv/more_info/proddisp.aspx?prod_id=TGA2511
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TGA2511 LNA
Noise Figure Performance
http://www.triquint.com/prodserv/more_info/proddisp.aspx?prod_id=TGA2511
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TGA2511 LNA
P1dB Performance
http://www.triquint.com/prodserv/more_info/proddisp.aspx?prod_id=TGA2511
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TGA2511 LNA
OIP3 Performance
http://www.triquint.com/prodserv/more_info/proddisp.aspx?prod_id=TGA2511
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Hittite HMC564LC4 LNA
GaAs pHEMT Low Noise Amplifier
Typical performance: Frequency range: 7-14 GHz
Noise Figure = 1.8 dB
Gain = 17 dB
Functional Diagram
= m
Single supply: 3V @ 51mA 50-ohm in/out
4x4 mm package
http://www.hittite.com/content/documents/data_sheet/hmc564lc4.pdf
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Hittite HMC564LC4 LNAParameter Typical Worst Case Units
Frequency range 7 14 7 - 14 GHz
Drain voltage, Vd 3.0 3.0 V
Drain current, Id 51 75 mA
Small-signal gain, S21 17 14 dB
Input return loss, S11 16 15 dB
Output return loss, S22 14 13 dB
Noise figure 1.8 2.2 dB
Output power @ 1dB comp., P1dB 13 10 dBm
OIP3 (TOI ref. to output) 25 25 dBm
[Source: www.hittite.com]
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Temperature Performance will vary over temperature
Variation must be comprehended in systemspecs over expected temp range
, ,
sensitive to temp variations
Gain ~ -0.01 dB/oC per stage
Ex: 2-stage LNA: G=2.5 dB for T=125C Noise Figure ~ +0.008 dB/oC
Ex: 2-stage LNA: F=1.0 dB for T=125C
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