Transcript No Slide Title

Time
Voltage
Voltage
Sources Generate Sine Waves
Oscilloscope
Frequency
Spectrum Analyzer
This is the ideal output: most specs deal with deviations from the
ideal and adding modulation to a sine wave
3-6 GHz
Source Basics
Millimeter
Microwave
RF
20-50 GHz
300 GHz
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Types of Sources

CW
– generates

a single frequency, fixed sine wave
Swept
– sweeps
over a range of frequencies
– may be phase continuous

Signal Generator
– adds
modulation
– produces “real world” signal
Source Basics
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CW Source Specifications
...Frequency



Range: Range of frequencies covered by the source
Resolution: Smallest frequency increment.
Accuracy: How accurately can the source frequency be
set.
EXAMPLE
Accuracy =
Voltage
Uncertainty
t aging
=
t cal =
CW frequency = 1 GHz
aging rate = 0.152 ppm/year
time since last calibrated = 1 year
_
=
 Accuracy +
Frequency
Source Basics
f CW =
+_ f CW * t aging * t cal
152
Hz
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CW Source Specifications
...Amplitude





Range (-136dBm to +13dBm)
Accuracy (+/- 0.5dB)
Resolution (0.02dB)
Switching Speed (25ms)
Reverse Power Protection
Source protected from accidental transmission from
DUT
What ismax
P
Voltage
DUT
out?
How
accurate is
this number?
min
What is P
Frequency
Source Basics
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out?
CW Source Specifications
...Spectral Purity



Phase Noise
Residual FM
Spurious
Residual FM is the
integrated phase noise
over 300 Hz - 3 kHz BW
CW output
phase
noise
non-harmonic spur
~65dBc
harmonic spur
~30dBc
sub-harmonics
0.5 f0
2 f0
Source Basics
f0
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CW Source Specifications
... Spectral Purity: Phase Noise
CW output
measured as dBc/Hz
frequency
TRACE A:
Ch1 PM PSD
A Marker
10 000 Hz
75 dBc/Hz
LogMag
5 dBc/div
-105 dBc/Hz
-125 dBc/Hz
Source Basics
1k
10k
100k
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RF CW Block Diagram
Synthesizer Section
Frac-N
Output Section
Output
Attenuator
ALC
Modulator
Phase
Detector
VCO
divide
by X
Reference
Oscillator
Reference Section
Source Basics
ALC
Driver
ALC Detector
ALC = automatic level control
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RF CW Block Diagram
Reference Section
to synthesizer section
divide
by X
Phase
Detector
Optional External
Reference Input
Source Basics
Reference Oscillator (TCXO or OCXO)
Aging Rate
TCXO
+/- 2ppm/year
OCXO
+/- 0.1 ppm /year
Temp.
+/- 1ppm
+/- 0.01 ppm
Line Voltage
+/- 0.5ppm
+/- 0.001 ppm
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RF CW Block Diagram
Synthesizer Section
...produces accurate, clean signals
N = 93.1
Front
panel
control
Frac-N
5MHz
to output section
Phase
Detector
X
VCO
2
multiplier
931 MHz
5MHz
from reference section
Source Basics
465.5 MHz
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RF CW Block Diagram
Synthesizer Section
PLL / Fractional - N
...suppresses phase noise
phase noise of source
reference
oscillator
phase
detector
noise
20logN
VCO noise
Source Basics
phase-locked-loop (PLL)
bandwidth selected for
optimum noise performance
broadband
noise floor
frequency
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RF CW Block Diagram
Output Section

ALC
–maintains
output
power by
adding/subtracting
power as needed

from
synthesizer
section
ALC
Modulator
Output
Attenuator
source output
Output Attenuator
–mechanical
or
electronic
–provides attentuation
to achieve wide output
range (e.g. -136dBm to
+13dBm)
ALC
Driver
ALC Detector
ALC = automatic level control
Source Basics
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mWave CW Block Diagram
Reference Section
Frac
N
ALC
Modulator
Phase
Det
Output
Attenuator
VCO
Sampler
by X
Ref Osc
YIG
Oscillator
Phase
Detector
Tuning
Coils
ALC
Driver
Frac-N
Synthesizer
Section
Phase
Detector
VCO
Source Basics
ALC Detector
Output Section
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Applications & Critical Specifications

Local Oscillator
– phase
noise
– frequency accuracy

Amplifier Distortion
– spurious
– TOI

(for system)
Receiver Testing
– Spurious
spurious
 level accuracy

Source Basics
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Applications & Critical Specifications
As a Local Oscillator
DUT
IF signal
poor frequency accuracy
will cause transmitter to
be at the wrong
frequency
Source Basics
transmitter output
poor phase noise spreads
energy into adjacent
channels
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Applications & Critical Specifications
Amplifier Testing
f1
DUT
Intermodulation
Distortion
output RF
f2
isolator
f1
fL = 2f1 - f2
f2
test system third order
products will also fall here
spurious signals from
source can corrupt
measurement
fU = 2f2 - f1
frequency
Source Basics
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2000
Applications & Critical Specifications
Receiver Testing
Receiver Selectivity
in-channel signal
(modulated signal)
IF
signal
out-of-channel signal
(CW or modulated signal)
DUT
source output
IF Rejection Curve
Level (dBm)
spur from source and/or high levels
of phase noise can cause a good
receiver to fail
Frequency
Source Basics
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Applications & Critical Specifications

Frequency Response
–
–
–
–
–

Amplifier Compression
–
Source Basics
Frequency Accuracy
Output Power (Level) Accuracy
Flatness
Speed
residual FM
Power Range
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Applications & Critical Specifications
Amplifier Compression
Power Range

1 dB compression
point
Power In
The 1 dB compression point is a common amplifier specification used to
identify the linear operating range of an amplifier. Power sweep is available
on some Agilent sources.
Source Basics
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Signal Generators

Calibrated modulation
– Analog (AM, FM, PM, Pulse)
– Digital (I-Q)
– Format Specific(TDMA,CDMA, etc.)
Source Basics
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Modulation
...Where the information resides
p f(t)f+ (t)]
V= A(t) sin[2
AM, Pulse
FM
PM
V= A(t) sin[
q (t)]
Source Basics
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Modulation: Analog
Amplitude Modulation
Voltage
Carrier
Time
Important Signal Generator Specs
for Amplitude Modulation

Modulation



Source Basics
Modulation frequency
Linear AM
Log AM
Depth of modulation (Mod
Index)
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Modulation: Analog
Frequency Modulation
p cf b
A sin[2
t + m(t)]
V=
b=D F
dev
/F
Important Signal Generator Specs
for Frequency Modulation
mod
Voltage



Time


Source Basics
Frequency Deviation
Modulation Frequency
dcFM
Accuracy
Resolution
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Modulation: Analog
Phase Modulation
V=
Voltage
b = Df
A sin[2 p
t + m(t)]
c f b
peak
Important Signal Generator Specs
for Phase Modulation
Time




Source Basics
Phase deviation
Rates
Accuracy
Resolution
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Modulation: Analog
Pulse Modulation
T
Rate=1/T
Important Signal Generator Specs
for Pulse Modulation
Power
Rise
time
Pulse
On/Off ratio

t

Time

Width

1/T
Pulse width
Pulse period
On/Off ratio
Rise time
Power
1/t
Source Basics
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Digital Modulation
...signal characteristics to modify
Amplitude
Frequency
Phase
Both Amplitude
and Phase
Source Basics
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Digital Modulation
Polar Display: Magnitude & Phase Represented Together
Phase
0 deg


Source Basics
Magnitude is an absolute value
Phase is relative to a reference signal
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Digital Modulation
Signal Changes or Modifications
Phase
0 deg
Magnitude Change
Phase
0 deg
Phase Change
0 deg
0 deg
Both Change
Frequency Change
Source Basics
Copyright
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Digital Modulation
...Binary Phase Shift Keying (BPSK)
V= A sin[2
p ft f+ (t)]
f (t) =
f1
f2
Source Basics
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Digital Modulation
BPSK IQ Diagram
Q
1
0
I
One Bit Per Symbol
Symbol Rate = Bit Rate
Source Basics
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Digital Modulation
...Quadrature Phase Shift Keying (QPSK)
p ftf+ (t)]
V= A sin[2
f (t) =
Source Basics
f1 = 3p /4
f2 = p /4
f3 = - p /4
f4 = - 3p
/4
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Digital Modulation
QPSK IQ Diagram
01
Q
00
I
11
Source Basics
10
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Digital Modulation
p/4 DQPSK IQ Diagram Q
I
Source Basics
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Digital Modulation
Modulation Accuracy
Q
Magnitude Error (IQ error mag)
Error Vector
Test
Signal
f
Ideal (Reference) Signal
Phase Error (IQ error phase)
I
Source Basics
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2000
Applications and Critical Specifications
Analog and Digital

Receiver Sensitivity
–
–
–

Receiver Selectivity
–
–
–

phase noise
spurious
spectral accuracy
Spectral Regrowth
–
Source Basics
frequency accuracy
level accuracy
error vector magnitude
ACP performance
Copyright
2000
Applications and Critical Specifications
Receiver Sensitivity

Frequency Accuracy
frequency inaccuracy
amplitude inaccuracy
Want to measure
sensitivity in a channel
Measurement impaired by
frequency inaccuracy
input for signal
generator
DUT
Source Basics
Copyright
2000
Applications and Critical Specifications
Receiver Sensitivity

Level Accuracy
Customer is testing a -110 dB sensitivity pager:
X= Failed unit
O=Passed unit
-110 dB specification
X
X
X X X
O
Actual output power= -114 dBm
Set source to -115 dBm
Frequency
Case 1: Source has +/-5 dB of
output power accuracy at
-100 to -120 dBm output power.
Source Basics
-110 dB specification
X
X
Set source to -111 dBm
O O O
Actual output power= -112 dBm
O
Frequency
Case 2: Source has +/-1 dB of
output power accuracy at
-100 to -120 dBm output power.
Copyright
2000
Applications and Critical Specifications
Receiver Sensitivity

Error Vector Magnitude (EVM)
e.g. TETRA Signal
p /4 DQPSK
EVM < 1.0%
Source Basics
Error
Vector
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Applications and Critical Specifications
Receiver Selectivity


Phase Noise
Spurious
in-channel signal
(modulated signal)
IF
signal
out-of-channel signal
(CW or modulated signal)
DUT
IF Rejection Curve
Level (dBm)
spur from source and/or high
levels of phase noise can cause a
good receiver to fail
Frequency
Source Basics
Copyright
2000
Applications and Critical Specifications
Receiver Selectivity
Spectral Accuracy:
 EVM
 ACP
Source Basics
GSM Signal
0.3GMSK
Copyright
2000
Applications and Critical Specifications
Spectral Regrowth

ACP Performance
DUT
Output from amplifier
Input from signal generator
Source Basics
Copyright
2000