130310124026_Signal Generator (Source) Basics.ppt

Source Basics Copyright
2000
Agenda
 Types of sources
 CW
 Swept
 Signal Generator
 Block Diagrams
 Applications
 Specifications

2000
Sources Generate Sine Waves
Voltage
Time
Voltage
Frequency
This is the ideal output: most specs deal with deviations from the
ideal and adding modulation to a sine wave
RF Microwave Millimeter
20-50 GHz 300 GHz
3-6 GHz
Spectrum Analyzer
Oscilloscope

2000
Types of Sources
 CW
– generates a single frequency, fixed sine wave
 Swept
– sweeps over a range of frequencies
– may be phase continuous
– adds modulation
– produces “real world” signal

2000
CW Source Specifications
...Frequency
Voltage
Frequency
Uncertainty
 Range: Range of frequencies covered by the source
 Resolution: Smallest frequency increment.
 Accuracy: How accurately can the source frequency be
set.
EXAMPLE
Accuracy =
= CW frequency = 1 GHz
= aging rate = 0.152 ppm/year
= time since last calibrated = 1 year

+
_ fCW
taging cal
t
* *
fCW
taging
cal
t
Accuracy = 152
Hz
+
_

2000
...Amplitude
DUT
Source protected from accidental transmission from
DUT
Voltage
Frequency
How
accurate is
this number?
What is P out?
What is P out?
max
min
 Range (-136dBm to +13dBm)
 Accuracy (+/- 0.5dB)
 Resolution (0.02dB)
 Switching Speed (25ms)
 Reverse Power Protection

2000
 Phase Noise
 Residual FM
 Spurious
...Spectral Purity
non-harmonic spur
~65dBc
harmonic spur
~30dBc
CW output
Residual FM is the
integrated phase noise
over 300 Hz - 3 kHz BW phase
noise
0.5 f0 f0
2f0
sub-harmonics

2000
... Spectral Purity: Phase Noise
CW output
frequency
measured as dBc/Hz
Ch1 PM PSD
1k 10k 100k
TRACE A:
A Marker 10 000 Hz
75 dBc/Hz
-125 dBc/Hz
LogMag
5 dBc/div
-105 dBc/Hz

2000
RF CW Block Diagram
Reference
Oscillator
VCO
Phase
Detector
Frac-N
divide
by X
ALC
Modulator
ALC
Driver
ALC Detector
Output
Attenuator
ALC = automatic level control
Reference Section
Synthesizer Section
Output Section

2000
RF CW Block Diagram
Reference Section
Phase
Detector
Optional External
Reference Input Reference Oscillator (TCXO or OCXO)
TCXO OCXO
Aging Rate +/- 2ppm/year +/- 0.1 ppm /year
Temp. +/- 1ppm +/- 0.01 ppm
Line Voltage +/- 0.5ppm +/- 0.001 ppm
to synthesizer section
divide
by X

2000
RF CW Block Diagram
Synthesizer Section
VCO
Phase
Detector
Frac-N
from reference section
to output section
X 2
multiplier
Front
panel
control
5MHz
465.5 MHz
N = 93.1
931 MHz
5MHz
...produces accurate, clean signals

2000
RF CW Block Diagram
Synthesizer Section
reference
oscillator
phase noise of source
VCO noise
phase
detector
noise broadband
noise floor
20logN
phase-locked-loop (PLL)
bandwidth selected for
optimum noise performance
PLL / Fractional - N
...suppresses phase noise
frequency

2000
RF CW Block Diagram
Output Section
ALC = automatic level control
ALC
Modulator
ALC
Driver
ALC Detector
Output
Attenuator
from
synthesizer
section
source output
 ALC
–maintains output
power by
adding/subtracting
power as needed
 Output Attenuator
–mechanical or
electronic
–provides attentuation
to achieve wide output
range (e.g. -136dBm to
+13dBm)

2000
mWave CW Block Diagram
ALC Detector
ALC
Modulator
ALC
Driver
Output
Attenuator
Sampler
Reference Section
Synthesizer
Section
Output Section
Ref Osc
VCO
Phase
Det
Frac
N
by X
VCO
Phase
Detector
Frac-N
Phase
Detector
Tuning
Coils
YIG
Oscillator

2000
Applications & Critical Specifications
 Local Oscillator
– phase noise
– frequency accuracy
 Amplifier Distortion
– spurious
– TOI (for system)
 Receiver Testing
– Spurious
 spurious
 level accuracy

2000
As a Local Oscillator
IF signal transmitter output
poor phase noise spreads
energy into adjacent
channels
poor frequency accuracy
will cause transmitter to
be at the wrong
frequency
DUT

2000
Amplifier Testing
f2
f1
fU = 2f2 - f1
fL = 2f1 - f2
spurious signals from
source can corrupt
measurement
frequency
test system third order
products will also fall here
output RF
isolator
f1
f2
DUT
Intermodulation
Distortion

2000
Receiver Testing
IF Rejection Curve
Frequency
Level
(dBm)
spur from source and/or high levels
of phase noise can cause a good
receiver to fail
source output
IF
signal
in-channel signal
(modulated signal)
out-of-channel signal
(CW or modulated signal)
DUT
Receiver Selectivity

2000
Agilent Families of CW Generators
RF
Microwave
Agilent 8664/65 family
 100 MHz - 6 GHz
 Low out channel noise
 AM/FM/Pulse.
Agilent 8662/63 family
 100 KHz - 2.5 GHz
 Low in channel noise
 AM/FM/Phase/Pulse
Agilent 83711/12B
family
 10 MHz - 20 GHz
 CW only

2000
Sweeper Specifications
...Frequency
 ramp sweep
– accuracy
– sweep time
– resolution
 step sweep
– accuracy
– number of points
– switching time
time
f2
t2
t1
f1
t4
t3
t1 t2
f4
f3
f1
f2

2000
Sweeper Specifications
...Amplitude
Frequency Sweep
 Level Accuracy
 Flatness
 Source Match (SWR)
Power Sweep
 Power Sweep Range
 Power Slope Range
 Source Match (SWR)
flatness spec
level accuracy
spec
f1 f2
frequency
power
power
}
P2
P1
power sweep
range
t1 t2

2000
 Frequency Response
– Frequency Accuracy
– Output Power (Level) Accuracy
– Flatness
– Speed
– residual FM
 Amplifier Compression
– Power Range

2000
Frequency Response Testing
LO
Sweeper Input
 Frequency Accuracy
 Output Power (Level) Accuracy
 Flatness
 Speed
 residual FM

2000
Frequency Response Testing
Center 2 450.212 MHz Span 1 099.577 MHz
1
1
3
5 6
BW: 429.600 MHz
CF: 2405.782 MHz
Q: 5.60
Loss: -0.84 dB
1:Transmission Log Mag 5.0 dB/ Ref -15.00 dB
-35
-30
-25
-20
-10
-5
0
5
Abs
dB
Ch1
Who Cares About Accuracy?

2000
Amplifier Compression
Power In
1 dB compression
point
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.
 Power Range

2000
Synthesized Sweep Generators
 Agilent 83750 Series
 Step/Analog sweep
 AM/FM/Phase modulation
 10MHz to 20GHz
 up to 110GHz with 83550 series
 modules and amplifier
 Agilent 8360L Series
 Step/Analog sweep
 8510/8757 Compatibility
 10MHz to 50GHz
 up to 110GHz with 83550 series
modules

2000
Signal Generators
 Calibrated modulation
– Analog (AM, FM, PM, Pulse)
– Digital (I-Q)
– Format Specific(TDMA,CDMA, etc.)

2000
Modulation
...Where the information resides
AM, Pulse
FM PM
q
V= A(t) sin[ (t)]
p
V= A(t) sin[2 f(t) + (t)]
f

2000
Modulation: Analog
Amplitude Modulation
Important Signal Generator Specs
for Amplitude Modulation
Voltage
Time
Carrier
Modulation
 Modulation frequency
 Linear AM
 Log AM
 Depth of modulation (Mod
Index)

2000
Modulation: Analog
Frequency Modulation
Voltage
Time
for Frequency Modulation
V= A sin[2 f t + m(t)]
p c b
F /F
dev mod
b = D
 Frequency Deviation
 Modulation Frequency
 dcFM
 Accuracy
 Resolution

2000
Modulation: Analog
Phase Modulation
b = Df peak
V= A sin[2 p f t + m(t)]
for Phase Modulation
 Phase deviation
 Rates
 Accuracy
 Resolution
Voltage
Time
c b

2000
Modulation: Analog
Pulse Modulation
Time
Pulse
On/Off ratio
Rise
time
Rate=1/T T
Width
Power
t
1/t
1/T
Power
for Pulse Modulation
 Pulse width
 Pulse period
 On/Off ratio
 Rise time

2000
Digital Modulation
...signal characteristics to modify
Amplitude
Frequency
Phase
Both Amplitude
and Phase

2000
Digital Modulation
Polar Display: Magnitude & Phase Represented Together
 Magnitude is an absolute value
 Phase is relative to a reference signal
Phase
0 deg

2000
Digital Modulation
Signal Changes or Modifications
Phase
0 deg
Magnitude Change
Phase
0 deg
Phase Change
Frequency Change
Both Change
0 deg
0 deg

2000
Digital Modulation
...Binary Phase Shift Keying (BPSK)
f
V= A sin[2 ft + (t)]
(t) =
f1
f2
p f

2000
Digital Modulation
BPSK IQ Diagram
I
Q
0
1
One Bit Per Symbol
Symbol Rate = Bit Rate

2000
Digital Modulation
...Quadrature Phase Shift Keying (QPSK)
V= A sin[2 ft + (t)]
f(t) =
f1 = 3 /4
p
f2 = /4
p
f3 = - /4
p
f4 = - 3
/4
p
p f

2000
Digital Modulation
QPSK IQ Diagram
I
Q
00
01
10
11

2000
Digital Modulation
p/4 DQPSK IQ Diagram
I
Q

2000
Digital Modulation
Modulation Accuracy
I
Q Magnitude Error (IQ error mag)
Error Vector
Ideal (Reference) Signal
Phase Error (IQ error phase)
Test
Signal
f

2000
Digital Signal Generator Block Diagram
IQ Modulator
– modulation
quality
Baseband Generator
– modulation quality
– adjacent channel
performance
– supported modulation
formats
reference section
(supplies timing)
to output section

2000
Digital Modulation
PSK Implementation: IQ Method
p/2
Carrier
 Good Interface with Digital Signals and
Circuits
 Can be Implemented with Simple Circuits
 Can be Modified for Bandwidth Efficiency
I:
Q:

2000
IQ Modulator
p/2
DAC
DAC
Ext I
Ext Q
from synthesizer
section
to output section
Q from Baseband Generator
I from Baseband Generator

2000
Baseband Generator
DAC
DAC
Pattern RAM Constellation
Map and
Baseband Filters
Timing
Data
Data Clock
Symbol
Clock
From CPU
I
Q
Analog
Reconstruction
Filters

2000
Digital Signal Generator
Format Specific Digital Signals
NADC (TDMA IS-54)
Parameter Specification
Access Method TDMA/FDD
Modulation p/4 DQPSK
Channel Bandwidth 30 kHz
Reverse Channel
Frequency Band
824 - 849 MHz
Forward Channel
Frequency Band
869 - 894 MHz
Filtering 0.35 RRC

2000
Digital Signal Generator
Access and Framing
one frame = 1944 bits (972 symbols) = 40ms; 25frames/sec
slot 1 slot 2 slot 3 slot 4 slot
5 slot 6
324 bit (162 symbols) = 6.667ms
G R Data Sync Data SACCH
CDVCC Data
6 6 16 28 122 12 12
122 Mobile to Base Station

2000
Applications and Critical Specifications
Analog and Digital
 Receiver Sensitivity
– frequency accuracy
– level accuracy
– error vector magnitude
 Receiver Selectivity
– phase noise
– spurious
– spectral accuracy
 Spectral Regrowth
– ACP performance

2000
Receiver Sensitivity
Want to measure
sensitivity in a channel
Measurement impaired by
frequency inaccuracy
frequency inaccuracy
amplitude inaccuracy
input for signal
generator
DUT
 Frequency Accuracy

2000
Customer is testing a -110 dB sensitivity pager:
-110 dB specification
Case 1: Source has +/-5 dB of
output power accuracy at
-100 to -120 dBm output power.
Set source to -115 dBm
Actual output power= -114 dBm
X
X
X X
X
O
Case 2: Source has +/-1 dB of
output power accuracy at
-100 to -120 dBm output power.
-110 dB specification
Set source to -111 dBm
Actual output power= -112 dBm
X
X
O O
O
O
X= Failed unit
O=Passed unit
Frequency Frequency
 Level Accuracy

2000
 Error Vector Magnitude (EVM)
Error
Vector
p
e.g. TETRA Signal
/4 DQPSK
EVM < 1.0%

2000
IF Rejection Curve
Frequency
Level
(dBm)
spur from source and/or high
levels of phase noise can cause a
good receiver to fail
IF
signal
in-channel signal
(modulated signal)
out-of-channel signal
(CW or modulated signal) DUT
 Phase Noise
 Spurious

2000
GSM Signal
0.3GMSK
Spectral Accuracy:
 EVM
 ACP

2000
Spectral Regrowth
Input from signal generator
Output from amplifier
DUT
 ACP Performance

2000
Agilent Families of Signal Generators
RF
Microwave
Agilent 8647/48
family
 9 KHz - 4 GHz
 AM/FM/Phase
 Paging, SMR,
Cordless
Agilent ESG family
 250 KHz - 4 GHz
 AM/FM/Phase/Pulse
 Digital/I-Q Mod
 GSM,CDMA,DECT...
Agilent 8360B family
10 MHz - 50 GHz
 AM/FM/Pulse
110 GHz with ext. module
Agilent 83730
family
 10 MHz - 20 GHz
 AM/FM/Pulse

2000
 Types of sources
 CW
 Swept
 Block Diagrams
 Applications
 Specifications
Agenda

130310124026_Signal Generator (Source) Basics.ppt

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