FeaTures
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LTC6946
Ultralow Noise and Spurious
0.37GHz to 6.39GHz Integer-N
Synthesizer with Integrated VCO
DescripTion
The
LTC
®
6946
is a high performance, low noise, 6.39GHz
phase-locked loop (PLL) with a fully integrated VCO,
including a reference divider, phase-frequency detector
(PFD) with phase-lock indicator, ultralow noise charge
pump, integer feedback divider, and VCO output divider.
The charge pump contains selectable high and low voltage
clamps useful for VCO monitoring.
The integrated low noise VCO uses no external components.
It is internally calibrated to the correct output frequency
with no external system support.
The part features a buffered, programmable VCO output
divider with a range of 1 through 6, providing a wide
frequency range.
Frequency Coverage Options
LTC6946-1
LTC6946-2
LTC6946-3
LTC6946-4
O DIV=1 2.240 to 3.740 3.080 to 4.910 3.840 to 5.790 4.200 to 6.390
O DIV=2 1.120 to 1.870 1.540 to 2.455 1.920 to 2.895 2.100 to 3.195
0 DIV=3
0.747 to 1.247 1.027 to 1.637 1.280 to 1.930 1.400 to 2.130
O DIV=4 0.560 to 0.935 0.770 to 1.228 0.960 to 1.448 1.050 to 1.598
O DIV=5 0.448 to 0.748 0.616 to 0.982 0.768 to 1.158 0.840 to 1.278
O DIV=6 0.373 to 0.623 0.513 to 0.818 0.640 to 0.965 0.700 to 1.065
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Low Noise Integer-N PLL with Integrated VCO
–226dBc/Hz Normalized In-Band Phase Noise Floor
–274dBc/Hz Normalized In-Band 1/f Noise
–157dBc/Hz Wideband Output Phase Noise Floor
Excellent Spurious Performance
Output Divider (1 to 6, 50% Duty Cycle)
Output Buffer Muting
Low Noise Reference Buffer
Charge Pump Current Adjustable from 250µA to
11.2mA
Configurable Status Output
SPI Compatible Serial Port Control
PLLWizard™ Software Design Tool Support
applicaTions
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Wireless Base Stations (LTE, WiMAX, W-CDMA, PCS)
Broadband Wireless Access
Military and Secure Radio
Test and Measurement
L,
LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks and
PLLWizard is a trademark of Linear Technology Corporation. All other trademarks are the
property of their respective owners.
Typical applicaTion
5.7GHz Wideband Receiver
4.7nF
5V
15
0.01µF
V
VCO+
GND
2.2µF
CM
A
CM
B
CM
C
GND
TB
57nF
0.01µF
3.3V
PHASE NOISE (dBc/Hz)
LTC6946-3 PLL Phase Noise
–80
–90
–100
–110
–120
–130
RMS NOISE = 0.61°
–140 RMS JITTER = 296fs
f
RF
= 5.7GHz
–150 f
PFD
= 10MHz
BW = 85kHz
–160
1M
1k
100
10k
100k
OFFSET FREQUENCY (Hz)
97.6
TUNE
1µF
0.01µF
68nH
3.3V
0.01µF
GND
V
CP+
CP
BB
V
RF+
LTC6946-3
RF
+
RF
–
GND
MUTE
SCLK
REFO
STAT
SDO
V
D+
SDI
CS
68nH RF INPUT
SIGNAL
100pF
RF
LO IF
TO IF
PROCESSING
3.3V
0.01µF
1µF
1µF
10MHz
51.1
3.3V
V
REF+
REF
+
REF
–
V
REFO+
100pF
50
6946 TA01a
+
3.3V
0.1µF
SPI BUS
0.1µF
UNUSED OUTPUT
IS AVAILABLE
FOR OTHER USE
10M 40M
6946 TA01b
6946fb
For more information
www.linear.com/LTC6946
1
LTC6946
absoluTe MaxiMuM raTings
(Note 1)
pin conFiguraTion
TOP VIEW
V
REF+
REF
–
REF
+
V
CP+
+
Supply Voltages
V
+
(V
REF+
, V
REFO+
, V
RF+
, V
D+
) to GND ..................3.6V
V
CP+
, V
VCO+
to GND .............................................5.5V
Voltage on CP Pin .................GND – 0.3V to V
CP+
+ 0.3V
Voltage on All Other Pins ..........GND – 0.3V to V
+
+ 0.3V
Operating Junction Temperature Range, T
J
(Note 2)
LTC6946I ............................................... –40°C to 105°C
Junction Temperature, T
JMAX
................................ 125°C
Storage Temperature Range .................. –65°C to 150°C
28 27 26 25 24 23
V
REFO
+ 1
REFO 2
STAT 3
CS
4
SCLK 5
SDI 6
SDO 7
V
D+
8
9 10 11 12 13 14
MUTE
GND
RF
–
RF
+
V
RF
BB
29
GND
22 V
VCO+
21 GND
20 CM
A
19 CM
B
18 CM
C
17 GND
16 TB
15 TUNE
UFD PACKAGE
28-LEAD (4mm
×
5mm) PLASTIC QFN
T
JMAX
= 125°C,
θ
JCbottom
= 3°C/W,
θ
JCtop
= 26°C/W
EXPOSED PAD (PIN 29) IS GND, MUST BE SOLDERED TO PCB
orDer inForMaTion
LEAD FREE FINISH
LTC6946IUFD-1#PBF
LTC6946IUFD-2#PBF
LTC6946IUFD-3#PBF
LTC6946IUFD-4#PBF
TAPE AND REEL
LTC6946IUFD-1#TRPBF
LTC6946IUFD-2#TRPBF
LTC6946IUFD-3#TRPBF
LTC6946IUFD-4#TRPBF
PART MARKING
69461
69462
69463
69464
PACKAGE DESCRIPTION
28-Lead (4mm
×
5mm) Plastic QFN
28-Lead (4mm
×
5mm) Plastic QFN
28-Lead (4mm
×
5mm) Plastic QFN
28-Lead (4mm
×
5mm) Plastic QFN
JUNCTION TEMPERATURE RANGE
–40°C to 105°C
–40°C to 105°C
–40°C to 105°C
–40°C to 105°C
Consult LTC Marketing for parts specified with wider operating temperature ranges.
Consult LTC Marketing for information on non-standard lead based finish parts.
For more information on lead free part marking, go to:
http://www.linear.com/leadfree/
For more information on tape and reel specifications, go to:
http://www.linear.com/tapeandreel/
available opTions
VCO FREQUENCY
RANGE (GHz)
2.240 to 3.740
3.080 to 4.910
3.840 to 5.790
4.200 to 6.390
PACKAGE STYLE
QFN-28 (UFD28)
LTC6946IUFD-1
LTC6946IUFD-2
LTC6946IUFD-3
LTC6946IUFD-4
0 DIV = 6
0.373 to 0.623
0.513 to 0.818
0.640 to 0.965
0.700 to 1.065
OUTPUT FREQUENCY RANGE vs OUTPUT DIVIDER SETTING (GHz)
0 DIV = 5
0.448 to 0.748
0.616 to 0.982
0.768 to 1.158
0.840 to 1.278
0 DIV = 4
0.560 to 0.935
0.770 to 1.228
0.960 to 1.448
1.050 to 1.598
0 DIV = 3
0.747 to 1.247
1.027 to 1.637
1.280 to 1.930
1.400 to 2.130
0 DIV = 2
1.120 to 1.870
1.540 to 2.455
1.920 to 2.895
2.100 to 3.195
0 DIV = 1
2.240 to 3.740
3.080 to 4.910
3.840 to 5.790
4.200 to 6.390
Overlapping Frequency Bands
GND
CP
2
6946fb
For more information
www.linear.com/LTC6946
LTC6946
elecTrical characTerisTics
SYMBOL
f
REF
V
REF
PARAMETER
Input Frequency
Input Signal Level
Input Slew Rate
Input Duty Cycle
Self-Bias Voltage
Input Resistance
Input Capacitance
Reference Output (REFO)
f
REFO
P
REFO
VCO
f
VCO
Frequency Range
LTC6946-1 (Note 3)
LTC6946-2 (Note 3)
LTC6946-3 (Note 3)
LTC6946-4 (Note 3)
LTC6946-1 (Notes 3, 4)
LTC6946-2 (Notes 3, 4)
LTC6946-3 (Notes 3, 4)
LTC6946-4 (Notes 3, 4)
l
l
l
l
l
l
The
l
denotes the specifications which apply over the full operating
junction temperature range, otherwise specifications are at T
A
= 25°C. V
REF+
= V
REF0+
= V
D+
= V
RF+
= 3.3V, V
CP+
= V
VCO+
= 5V unless
otherwise specified (Note 2). All voltages are with respect to GND.
CONDITIONS
l
MIN
10
0.5
20
TYP
MAX
250
UNITS
MHz
V
P-P
V/µs
%
Reference Inputs (REF
+
, REF
–
)
Single Ended, 1µF AC-Coupling Capacitors
l
l
2
50
2.7
1.65
6.2
1.85
8.4
3
2.25
11.6
V
kΩ
pF
Differential
Differential
l
Output Frequency
Output Power
Output Impedance, Disabled
f
REFO
= 10MHz, R
LOAD
= 50Ω
l
l
10
–0.2
800
2.24
3.08
3.84
4.20
4.7 to 7.2
4.7 to 7.0
4.0 to 6.0
4.5 to 6.5
0.373
1
50
111
2.4
–9.7
–6.8
–3.9
–1.2
136
250
3.2
MHz
dBm
Ω
3.74
4.91
5.79
6.39
GHz
GHz
GHz
GHz
%Hz/V
%Hz/V
%Hz/V
%Hz/V
K
VCO
Tuning Sensitivity
RF Output (RF
+
, RF
–
)
f
RF
O
Output Frequency
Output Divider Range
Output Duty Cycle
Output Resistance
Output Common Mode Voltage
P
RF(SE)
Output Power, Single Ended,
f
RF
= 900MHz
Output Power, Muted
Mute Enable Time
Mute Disable Time
Phase/Frequency Detector
f
PFD
t
LWW
Input Frequency
Lock Window Width
LKWIN[1:0] = 0
LKWIN[1:0] = 1
LKWIN[1:0] = 2
LKWIN[1:0] = 3
Increase in t
LWW
Moving from Locked State to
Unlocked State
l
6.39
6
GHz
%
All Integers Included
Single Ended, Each Output to V
RF+
RFO[1:0] = 0, R
Z
= 50Ω, LC Match
RFO[1:0] = 1, R
Z
= 50Ω, LC Match
RFO[1:0] = 2, R
Z
= 50Ω, LC Match
RFO[1:0] = 3, R
Z
= 50Ω, LC Match
R
Z
= 50Ω, Single Ended, f
RF
= 900MHz,
O = 2 to 6
l
l
l
l
l
l
l
l
l
l
159
V
RF+
–6.0
–3.6
–0.4
2.3
–60
110
170
100
Ω
V
dBm
dBm
dBm
dBm
dBm
ns
ns
MHz
ns
ns
ns
ns
%
Lock Indicator, Available on the STAT Pin and via the SPI-Accessible Status Register
3.0
10.0
30.0
90.0
22
t
LWHYS
Lock Window Hysteresis
6946fb
For more information
www.linear.com/LTC6946
3
LTC6946
elecTrical characTerisTics
SYMBOL
Charge Pump
I
CP
Output Current Range
Output Current Source/Sink Accuracy
Output Current Source/Sink Matching
12 Settings (See Table 5)
All Settings V
CP
= V
CP+
/2
I
CP
= 250µA to 1.4mA, V
CP
= V
CP+
/2
I
CP
= 2.0mA to 11.2mA, V
CP
= V
CP+
/2
l
l
The
l
denotes the specifications which apply over the full operating
junction temperature range, otherwise specifications are at T
A
= 25°C. V
REF+
= V
REF0+
= V
D+
= V
RF+
= 3.3V, V
CP+
= V
VCO+
= 5V unless
otherwise specified (Note 2). All voltages are with respect to GND.
PARAMETER
CONDITIONS
MIN
0.25
TYP
MAX
11.2
±6
±3.5
±2
0.1
170
0.5
5
0.84
–0.96
0.48
l
UNITS
mA
%
%
%
%/V
ppm/°C
nA
nA
V
V
V/V
Output Current vs Output Voltage Sensitivity (Note 5)
Output Current vs Temperature
Output Hi-Z Leakage Current
V
CLMP(LO)
V
CLMP(HI)
V
MID
R
N
V
IH
V
IL
V
IHYS
I
OH
I
OL
Low Clamp Voltage
High Clamp Voltage
Mid-Supply Output Bias Ratio
Divide Range
Divide Range
High Level Input Voltage
Low Level Input Voltage
Input Voltage Hysteresis
Input Current
High Level Output Current
Low Level Output Current
SDO Hi-Z Current
Digital Timing Specifications (See Figures 7 and 8)
t
CKH
t
CKL
t
CSS
t
CSH
t
CS
t
CH
t
DO
SCLK High Time
SCLK Low Time
CS
Setup Time
CS
High Time
SDI to SCLK Setup Time
SDI to SCLK Hold Time
SCLK to SDO Time
V
REF+
Supply Range
V
REFO+
Supply Range
V
D+
Supply Range
V
RF+
Supply Range
V
VCO+
Supply Range
V
CP+
Supply Range
To V
IH
/V
IL
/Hi-Z with 30pF Load
V
CP
= V
CP+
/2
I
CP
= 700µA, CPCLO = CPCHI = 0 (Note 5)
I
CP
= 11.2mA, CPCLO = CPCHI = 0 (Note 5)
CPCLO = 1
CPCHI = 1, Referred to V
CP+
Referred to (V
CP+
– GND)
All Integers Included
All Integers Included
MUTE, CS,
SDI, SCLK
MUTE, CS,
SDI, SCLK
MUTE, CS,
SDI, SCLK
MUTE, CS,
SDI, SCLK
SDO and STAT, V
OH
= V
D+
– 400mV
SDO and STAT, V
OL
= 400mV
1.0
Reference (R) Divider
1
32
1.55
0.8
250
l
l
l
l
1023
65535
counts
counts
V
V
mV
µA
mA
mA
µA
ns
ns
ns
ns
ns
ns
VCO (N) Divider
l
Digital Pin Specifications
l
l
±1
–2.3
1.8
2.6
±1
25
25
10
10
6
6
16
3.15
3.15
3.15
3.15
4.75
4.0
3.3
3.3
3.3
3.3
5.0
3.45
3.45
3.45
3.45
5.25
5.25
– 1.4
l
l
l
l
l
l
l
ns
V
V
V
V
V
V
Power Supply Voltages
l
l
l
l
l
l
4
6946fb
For more information
www.linear.com/LTC6946
LTC6946
elecTrical characTerisTics
SYMBOL
I
DD
I
CC(5V)
I
CC(REFO)
I
CC (3.3V)
PARAMETER
V
D+
Supply Current
Sum V
CP+
, V
VCO+
Supply Currents
V
REFO+
Supply Currents
Sum V
REF+
, V
RF+
Supply Currents
Power Supply Currents
Digital Inputs at Supply Levels
I
CP
= 11.2mA
I
CP
= 1.0mA
PDALL = 1
REFO Enabled, R
Z
=
∞
RF Muted, OD[2:0] = 1
RF Enabled, RFO[1:0] =0, OD[2:0] = 1
RF Enabled, RFO[1:0] = 3, OD[2:0] = 1
RF Enabled, RFO[1:0] =3, OD[2:0] = 2
RF Enabled, RFO[1:0] =3, OD[2:0] = 3
RF Enabled, RFO[1:0] =3, OD[2:0] = 4 to 6
PDALL = 1
l
l
l
l
l
l
l
l
l
l
l
l
The
l
denotes the specifications which apply over the full operating
junction temperature range, otherwise specifications are at T
A
= 25°C. V
REF+
= V
REF0+
= V
D+
= V
RF+
= 3.3V, V
CP+
= V
VCO+
= 5V unless
otherwise specified (Note 2). All voltages are with respect to GND.
CONDITIONS
MIN
TYP
MAX
500
50
28
405
7.8
65
76
85
103
108
113
195
–80
–130
–157
–77
–127
–156
–75
–126
–155
–73
–132
–154
–81
–132
–155
–84
–135
–156
–87
–138
–156
–89
–140
–157
–90
–141
–158
–226
–274
–99
0.17
–103
63
39
660
9.0
76
86
97
117
123
128
340
UNITS
µA
mA
mA
µA
mA
mA
mA
mA
mA
mA
mA
µA
dBc/Hz
dBc/Hz
dBc/Hz
dBc/Hz
dBc/Hz
dBc/Hz
dBc/Hz
dBc/Hz
dBc/Hz
dBc/Hz
dBc/Hz
dBc/Hz
dBc/Hz
dBc/Hz
dBc/Hz
dBc/Hz
dBc/Hz
dBc/Hz
dBc/Hz
dBc/Hz
dBc/Hz
dBc/Hz
dBc/Hz
dBc/Hz
dBc/Hz
dBc/Hz
dBc/Hz
dBc/Hz
dBc/Hz
dBc/Hz
°RMS
dBc
Phase Noise and Spurious
L
M
Phase Noise (LTC6946-1, f
VCO
= 3.0GHz, f
RF
10kHz Offset
= 3.0GHz, OD[2 :0] = 1 (Note 6))
1MHz Offset
40MHz Offset
Phase Noise (LTC6946-2, f
VCO
= 4.0GHz, f
RF
10kHz Offset
= 4.0GHz, OD[2 :0] = 1 (Note 6))
1MHz Offset
40MHz Offset
Phase Noise (LTC6946-3, f
VCO
= 5.0GHz, f
RF
10kHz Offset
= 5.0GHz, OD[2 :0] = 1 (Note 6))
1MHz Offset
40MHz Offset
VCO Phase Noise (LTC6946-4, f
VCO
=
10kHz Offset
6.0GHz, f
RF
= 6.0GHz, OD[2 :0] = 1 (Note 6)) 1MHz Offset
40MHz Offset
Phase Noise (LTC6946-3, f
VCO
= 5.0GHz, f
RF
10kHz Offset
= 2.50GHz, OD[2 :0] = 2 (Note 6))
1MHz Offset
40MHz Offset
Phase Noise (LTC6946-3, f
VCO
= 5.0GHz, f
RF
10kHz Offset
= 1.667GHz, OD[2 :0] = 3 (Note 6))
1MHz Offset
40MHz Offset
Phase Noise (LTC6946-3, f
VCO
= 5.0GHz, f
RF
10kHz Offset
= 1.25GHz, OD[2 :0] = 4 (Note 6))
1MHz Offset
40MHz Offset
Phase Noise (LTC6946-3, f
VCO
= 5.0GHz, f
RF
10kHz Offset
= 1.00GHz, OD[2 :0] = 5 (Note 6))
1MHz Offset
40MHz Offset
Phase Noise (LTC6946-3, f
VCO
= 5.0GHz, f
RF
10kHz Offset
= 0.833GHz, OD[2 :0] = 6 (Note 6))
1MHz Offset
40MHz Offset
L
M(NORM)
L
M(IB)
Normalized In-Band Phase Noise Floor
In-Band Phase Noise Floor
Integrated Phase Noise from
100Hz to 40MHz
Spurious
I
CP
= 11.2mA (Notes 7, 8, 9)
I
CP
= 11.2mA (Notes 7, 10)
(Notes 7, 8, 9, 11)
(Notes 8, 12)
f
OFFSET
= f
PFD
, PLL Locked (Notes 8, 12, 13)
L
M(NORM – 1/f)
Normalized In-Band 1/f Phase Noise
6946fb
For more information
www.linear.com/LTC6946
5
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