Transcript No Slide Title

What they are and how to use them
Source Basics
1
Agenda




Types of sources
CW
Swept
Signal Generator

Block Diagrams

Applications

Specifications
2
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
Millimeter
Microwave
RF
3-6 GHz
20-30 GHz
300 GHz
3
Types of Sources

CW
– generates

Swept
a single frequency, fixed sine wave
– sweeps
over a range of frequencies
– may be phase continuous

Signal Generator
– adds
modulation
– produces "real world" signal
4
Agenda




Types of sources
CW
Swept
Signal Generator

Block Diagrams

Applications

Specifications
5
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 = +
_ f CW * t aging* t cal
Voltage
Uncertainty
Frequency
f CW =
t aging =
=
t cal

CW frequency = 1 GHz
aging rate = 0.152ppm/year
time since last calibrated = 1 year
_ 152 Hz
Accuracy = +
6
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 is P max out?
DUT
Voltage

How accurate is this
number?
What is P minout?
Frequency
7
CW Source Specifications
...Spectral Purity



Phase Noise
Residual FM
Spurious
CW output
residual FM is
the integrated
phase noise
over 300 Hz - 3
sub-harmonics kHz BW
0.5f0
2f 0
phase
noise
f0
non-harmonic spur
~65dBc
harmonic spur
~30dBc
8
CW Source Specifications
... Spectral Purity: Phase Noise
CW output
measured as dBc/Hz
frequency
TRACE A:
-75
dB*
Ch1 PM PSD
A Marker
Y* = radrms^2/Hz
-104.177 dB*
10 000 Hz
LogMag
5
dB
/div
-125
dB*
1k
Start: 500 Hz
10k
100k
Stop: 100 kHz
9
CW Block Diagram
Synthesizer Section
–
–
–
–
range
resolution
switching speed
spectral purity
Output Section
–
–
–
–
Reference Section
–
–
range
level accuracy
amplitude switching
speed
reverse power
protection
frequency
stability
accuracy
10
RF CW Block Diagram
Synthesizer Section
Frac-N
Output Section
ALC
Modulator
Output
Attenuator
Phase
Detector
VCO
divide
by X
Reference
Oscillator
Reference Section
ALC
Driver
ALC Detector
ALC = automatic level control
11
RF CW Block Diagram
Reference Section
to synthesizer section
divide
by X
Phase
Detector
Optional External
Reference Input
Aging Rate
Temperatur
e
Line
Voltage
Reference Oscillator (TCXO or OCXO)
TCXO
OCXO
+/- 2ppm/year
+/- 0.1 ppm /year
+/- 1ppm/year
+/- 0.01 ppm/year
+/- 0.5ppm/year
+/- 0.001 ppm/year
12
RF CW Block Diagram
Synthesizer Section
...produces accurate, clean signals
N = 93.1
control
Frac-N
5MHz
Phase
Detector
X
VCO
2
multiplier
to output section
931 MHz
5MHz
from reference section
465.6 MHz
13
RF CW Block Diagram
Synthesizer Section
PLL / Fractional - N
...suppresses phase noise
phase noise of source
reference
oscillator
phase-locked-loop (PLL)
bandwidth selected for
optimum noise performance
phase
detector
noise
20logN
VCO noise
broadband
noise floor
frequency
14
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
15
mWave CW Block Diagram
Reference Section
Frac
N
ALC
Modulator
Phase
Det
VCO
Output
Attenuator
Sampler
by X
Ref Osc
YIG
Oscillator
Phase
Detector
Tuning
Coils
ALC
Driver
Frac-N
Synthesizer
Section
Phase
Detector
VCO
ALC Detector
Output Section
16
mWave CW Block Diagram
Reference Section
Frac-N
300 - 350 MHz
Phase
Detector
to synthesizer section
VCO
10 MHz
30 MHz
multiply
by X x3
Ext Ref
Reference
Oscillator
17
mWave CW Block Diagram
Synthesizer Section
Sampler
from reference section
IF
n = 29 then fLO = 8.99 GHz
divide
by x
and fIF = 20 MHz
Phase
Detector
Frac
N
Phase
Detector
from reference section
9.01 GHz
Tuning
Coils
divide
by y
YIG
Oscillator
VCO
18
mWave CW Block Diagram
Synthesizer Section
Comb Generator
Sampler mixes one of the
harmonics with the output of
the YIG oscillator
310 MHz
8.99 GHz
n=1
2
3
4
5
27
28
29
30
31
frequency
19
Applications & Critical Specifications

Local Oscillator
– phase
noise
– frequency accuracy

Amplifier Distortion
– spurious
– TOI

(for system)
Receiver Testing
– Spurious
spurious
level accuracy

20
Applications & Critical Specifications
As a Local Oscillator
DUT
IF signal
transmitter output
poor phase noise spreads
energy into adjacent channels
poor frequency accuracy
will cause transmitter to
be at the wrong
frequency
21
Applications & Critical Specifications
Amplifier Testing
Intermodulation
Distortion
f1
DUT
output RF
f2
isolator
f1
f2
test system third order
products will also fall here
spurious signals from
source can corrupt
measurement
fL = 2f 1 - f2
fU = 2f2 - f1
frequency
22
Applications & Critical Specifications
Receiver Testing
Spurious Immunity
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
23
Agenda




Types of sources
CW
Swept
Signal Generator

Block Diagrams

Applications

Specifications
24
Sweeper Specifications
...Frequency

ramp sweep
–
–
–
accuracy
sweep time
resolution
f2
f1
t1

time
step sweep
–
–
–
accuracy
number of points
switching time
t2
f4
f3
f2
f1
t1
t2
t3
t4
25
Sweeper Specifications
...Amplitude
Frequency Sweep
 Level Accuracy
 Flatness
Source Match (SWR)
power
level accuracy
spec
flatness spec
f1
P2
power
Power Sweep
 Power Sweep Range
Power Slope Range
 Source Match (SWR)
P1
frequency
f2
}
power sweep
range
26
Sweeper Block Diagram
Frequency Sweep: Open Loop




Phase continuous
PLL open
Synthesize start frequencies
Tuning characteristics must be precisely known
from reference section
mWave Source:
Synthesizer Section
Sampler
9.01 GHz
divide
by x
YIG
Oscillator
Phase
Detector
divide
by y
S/H
Tuning
Coils
DAC
27
Sweeper Block Diagram
Frequency Sweep: Closed Loop




Fully synthesized sweep
Phase continuous within
PLL never loses lock
Limited frequency range
Frac-N
RF Source:
Synthesizer Section
Phase
Detector
VCO
28
Sweeper Block Diagram
Power Sweep



Drive ALC Modulator
Level accuracy maintained
Broad sweeps may require switching output attentuator
from
synthesizer
section
ALC
Modulator
Output
Attenuator
source output
Output Section
ALC
Driver
ALC Detector
29
Applications & Critical Specifications

Frequency Response
–
Frequency Accuracy
Output Power (Level) Accuracy
Flatness
Speed
residual FM
–
Power Range
–
–
–
–

Amplifier Compression
30
Applications & Critical Specifications
Frequency Response Testing
Sweeper Input





Frequency Accuracy
Output Power (Level) Accuracy
Flatness
Speed
residual FM
LO
31
Applications & Critical Specifications
Frequency Response Testing
Who Cares About Accuracy?
1:Transmission
Log Mag
5.0 dB/
Ref -15.00 dB
BW: 429.600 MHz
CF: 2405.782 MHz
Q: 5.60
Loss: -0.84 dB
dB
5
1
0
3
-5
5
6
-10
Ch1
-20
-25
-30
1
-35
Abs
Center 2 450.212 MHz
Span 1 099.577 MHz
32
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 HP sources.
33
Agenda




Types of sources
CW
Swept
Signal Generator

Block Diagrams

Applications

Specifications
34
Signal Generators



Calibrated, variable frequency over a broad range
Calibrated, variable ouput level over a wide
dynamic range
Calibrated modulation
–
–
–
Analog (AM, FM, PM, Pulse)
Digital (IQ)
Format Specific
35
Modulation
...Where the information resides
V= V(t) sin[2 pf(t) + f(t)]
AM, Pulse
FM
PM
V= V(t) sin[ q(t)]
36
Modulation: Analog
Amplitude Modulation
Voltage
Carrier
Important Signal Generator Specs
for Amplitude Modulation
Time

Modulation



Modulation frequency
Linear AM
Log AM
Depth of modulation
(Mod Index)
37
Modulation: Analog
Frequency Modulation
V= V(t) sin[2 pf c t + b m(t)]
b = D Fdev /Fmod
Important Signal Generator Specs
for Frequency Modulation


Voltage

Time


Frequency Deviation
Modulation Frequency
dcFM
Accuracy
Resolution
38
Modulation: Analog
Phase Modulation
V= V(t) sin[2 pf c t + b m(t)]
b = Df peak
Voltage
Important Signal Generator Specs
for Phase Modulation


Time


Phase deviation
Rates
Accuracy
Resolution
39
Modulation: Analog
PM is Really the Same as FM...
FM Modulator
V= V(t) sin[2 pf c t + b m(t)]
PM Modulator
b = Df peak
b = D Fdev /Fmod
40
Modulation: Analog
Voltages of FM/PM Frequency Components
Bessel Functions of the First Kind
1
J0
0.8
J1
0.6
J2
0.4
J3
0.2
J4
J5
0
J6
-0.2
J7
-0.4
J8
-0.6
J9
0.0
2.0
4.0
6.0
b
8.0
9.9
J10
5.52
41
Modulation: Analog
Pulse Modulation
T
Rise
time
Power
Rate=1/T
Pulse
Important Signal Generator Specs
for Pulse Modulation
On/Off ratio


t
Time


Width
Pulse width
Pulse period
On/Off ratio
Rise time
Power
1/T
1/
t
42
Signal Generator Block Diagram
FM and PM
control
Frac-N
Phase
Detector
X
VCO
divide
by X
2
to output
section
multiplier
d/dt
function
generator
from reference section
external FM/PM input
43
Signal Generator Block Diagram
AM and Pulse
ALC
Modulator
Burst
Modulator
Output
Attenuator
from
synthesizer
section
function
generator
Ext AM
source output
ALC
Driver
Burst
Mod
Driver
ALC
Hold
ALC
Detector
Ext Pulse
44
Digital Modulation
...signal characteristics to modify
Amplitude
Frequency
Phase
Both Amplitude
and Phase
45
Digital Modulation
...Amplitude Shift Keying (ASK)
V= V(t) sin[2 pft + f ]
V(t) =
RF waveform
V
=
46
Digital Modulation
...Phase Shift Keying (BPSK)
V= Vo sin[2p ft +f (t)]
f (t) =
f1
f2
47
Digital Modulation
...Phase Shift Keying (QPSK)
V= Vo sin[2p ft +f (t)]
f(t) =
f1 = 3p
/4= p
f2
f/4
3 = -p
/4= - 3p
f4
/4
48
Digital Modulation
PSK Implementation: PLL Method
Frac-N
Phase
Detector
VCO
f(t)
d/dt
Reference Oscillator
external modulation input
49
Digital Modulation
PSK Implementation: IQ Method
V= Vo sin[2p ft +f (t)]
= Vo cos[f (t)] sin[2 pft] +
Vo sin[f (t)] sin[2 pft + p/2]
f (t) =
f1 = 3p
/4= p
f2
f/4
3 = -p
/4= - 3p
f4
/4
50
Digital Modulation
PSK Implementation: IQ Method
I:
Vo cos[f(t)] =
{
Vo
2
2
Vo
2
2
p/2
Q:
Vo sin[f(t)] =
{
Vo
sin[2pft]
2
2
Vo
2
2



Good Interface with Digital Signals and
Circuits
Can be Implemented with Simple Circuits
Can be Modified for Bandwidth Efficiency
51
Digital Modulation
QPSK IQ Diagram
Q
01
Vo
00
2
2
I
Vo
2
2
11
10
52
Digital Modulation
Polar Display: Magnitude & Phase Represented
Together
Phase
0 deg


Magnitude is an absolute value
Phase is relative to a reference signal
53
Digital Modulation
Signal Changes or Modifications
Phase
0 deg
Magnitude Change
Phase
0 deg
Phase Change
0 deg
0 deg
Both Change
Frequency Change
54
Digital Modulation
Modulation Accuracy
Q
Magnitude Error (IQ error mag)
Error Vector
Test
Signal
f
Ideal (Reference) Signal
Phase Error (IQ error phase)
I
55
Digital Signal Generator Block Diagram
IQ Modulator
–
modulation
quality
reference section
(supplies timing)
to output section
Baseband Generator
–
modulation quality
–
adjacent channel
performance
–
supported modulation
formats
56
Digital Signal Generator Block Diagram
IQ Modulator
I from Baseband Generator
Ext I
DAC
from synthesizer
section
p/2
to output
section
DAC
Ext Q
Q from Baseband Generator
57
Digital Signal Generator Block Diagram
Baseband Generator
From CPU
Pattern RAM
Constellation
Map and
Baseband Filters
Data
Data Clock
DAC
Analog
Reconstruction
Filters
I
DAC
Q
Timing
Symbol
Clock
58
Digital Signal Generator
Digital Signals
US-TDMA
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
59
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
6
R
6
Data Sync
16
28
Data
122
SACCH CDVCC Data
12
12
122
Mobile to Base Station
60
Applications and Critical Specifications
Analog and Digital

Receiver Sensitivity
–
–
–

Receiver Selectivity
–
–
–

frequency accuracy
level accuracy
error vector magnitude
phase noise
spurious
spectral accuracy
Spectral Regrowth
–
ACP performance
61
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
62
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
-110 dB specification
X
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.
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.
63
Applications and Critical Specifications
Receiver Sensitivity

Error Vector Magnitude (EVM)
e.g. TETRA Signal
p /4 DQPSK
EVM < 1.0%
Error
Vector
64
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
fndB = amar + aadj + as - 10log(Be/1Hz)
65
Applications and Critical Specifications
Receiver Selectivity
Spectral Accuracy:
 EVM
 ACP
GSM Signal
0.3GMSK
66
Applications and Critical Specifications
Spectral Regrowth

ACP Performance
DUT
Output from amplifier
Input from signal generator
67
Summary




Types of sources
CW
Swept
Signal Generator

Block Diagrams

Applications

Specifications
68