FeaTures
n
n
n
n
n
n
n
n
n
n
n
n
LTC6948
Ultralow Noise 0.37GHz to
6.39GHz Fractional-N Synthesizer
with Integrated VCO
DescripTion
The
LTC
®
6948
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), ultralow noise charge pump, fractional feedback
divider, and VCO output divider.
The fractional divider uses an advanced, 4th order Δ∑
modulator which provides exceptionally low spurious
levels. This allows wide loop bandwidths, producing
extremely low integrated phase noise values.
The programmable VCO output divider, with a range of 1
through 6, extends the output frequency range.
Output Frequency Options
LTC6948-1
O_DIV = 1
O_DIV = 2
O_DIV = 3
O_DIV = 4
O_DIV = 5
O_DIV = 6
LTC6948-2
LTC6948-3
LTC6948-4
2.240 to 3.740 3.080 to 4.910 3.840 to 5.790 4.200 to 6.390
1.120 to 1.870 1.540 to 2.455 1.920 to 2.895 2.100 to 3.195
0.747 to 1.247 1.027 to 1.637 1.280 to 1.930 1.400 to 2.130
0.560 to 0.935 0.770 to 1.228 0.960 to 1.448 1.050 to 1.598
0.448 to 0.748 0.616 to 0.982 0.768 to 1.158 0.840 to 1.278
0.373 to 0.623 0.513 to 0.818 0.640 to 0.965 0.700 to 1.065
Low Noise Fractional-N PLL with Integrated VCO
No ∆-∑ Modulator Spurs
18-Bit Fractional Denominator
–226 dBc/Hz Normalized In-Band Phase Noise Floor
–274 dBc/Hz Normalized In-Band 1/f Noise
–157 dBc/Hz Wideband Output Phase Noise Floor
Excellent Integer Boundary Spurious Performance
Output Divider (1 to 6, 50% Duty Cycle)
Output Buffer Muting
Reference Input Frequency Up to 425MHz
Fast Frequency Switching
FracNWizard™ Software Design Tool Support
applicaTions
n
n
n
n
Wireless Basestations (LTE, WiMAX, W-CDMA, PCS)
Microwave Data Links
Military and Secure Radio
Test and Measurement
L,
LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks and
FracNWizard is a trademark of Analog Devices, Inc. All other trademarks are the property of
their respective owners.
Typical applicaTion
6.3GHz Wideband Receiver
1.6nF
76.8
15
1µF
10µH
5V
76.8
–90
1µF
1µF
GND
REF
–
V
REF+
V
CP+
GND
V
VCO+
REF
+
STAT
CS
SCLK
SDI
SDO
LDO
V
D+
CP
BVCO
GND
CM
A
CM
B
CM
C
GND
TB
TUNE
1µF
2.2µF
0.01µF
56nF
0.01µF
PHASE NOISE (dBc/Hz)
1µF
–100
–110
–120
–130
RMS NOISE = 0.412°
–140 RMS JITTER = 183fs
f
PFD
= 50MHz
–150 LOOP BW = 186kHz
INTN = 0
CPLE = 1
–160
1M
1k
100
10k
100k
OFFSET FREQUENCY (Hz)
0.1µF 3.3V
2.4nF
LTC6948-4 Phase Noise,
f
RF
= 6236MHz
100MHz
51.1
SPI BUS
0.1µF
LTC6948-4
MUTE
V
RF+
GND
RF
–
RF
+
3.3V
3.3V
0.1µF
BB
UNUSED OUTPUT
AVAILABLE FOR
OTHER USE
50
3.3V
68nH
3.3V
0.01µF
100pF
R = 2, f
PFD
= 50MHz
N = 84 TO 127.8
LBW = 186kHz
O=1
10M 40M
6946 TA01b
0.1µF
68nH 100pF
f
LO
= 4200MHz TO 6390MHz IN 190.7Hz STEPS
RF INPUT SIGNAL
LO IF
RF
IF OUTPUT
6948 TA01a
6948fa
For more information
www.linear.com/LTC6948
1
LTC6948
absoluTe MaxiMuM raTings
(Note 1)
pin conFiguraTion
TOP VIEW
V
VCO+
22 BVCO
21 GND
20 CM
A
29
GND
19 CM
B
18 CM
C
17 GND
16 TB
15 TUNE
9 10 11 12 13 14
MUTE
V
RF+
GND
RF
–
RF
BB
+
Supply Voltages
V
+
(V
REF+
, 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)
LTC6948I ........................................... –40°C to 105°C
Junction Temperature, T
JMAX
................................ 125°C
Storage Temperature Range .................. –65°C to 150°C
V
REF+
REF
–
V
CP+
28 27 26 25 24 23
REF
+
1
STAT 2
CS
3
SCLK 4
SDI 5
SDO 6
LDO 7
V
D+
8
UFD PACKAGE
28-LEAD (4mm
×
5mm) PLASTIC QFN
T
JMAX
= 125°C,
θ
JCbottom
= 7°C/W
EXPOSED PAD (PIN 29) IS GND, MUST BE SOLDERED TO PCB
orDer inForMaTion
LEAD FREE FINISH
LTC6948IUFD-1#PBF
LTC6948IUFD-2#PBF
LTC6948IUFD-3#PBF
LTC6948IUFD-4#PBF
TAPE AND REEL
LTC6948IUFD-1#TRPBF
LTC6948IUFD-2#TRPBF
LTC6948IUFD-3#TRPBF
LTC6948IUFD-4#TRPBF
http://www.linear.com/product/LTC6948#orderinfo
PART MARKING
69481
69482
69483
69484
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 nonstandard 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)
LTC6948IUFD-1
LTC6948IUFD-2
LTC6948IUFD-3
LTC6948IUFD-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
6948fa
For more information
www.linear.com/LTC6948
LTC6948
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
D+
= V
RF+
= 3.3V, V
CP+
= V
VCO+
= 5V unless otherwise
specified (Note 2). All voltages are with respect to GND.
SYMBOL
f
REF
V
REF
PARAMETER
Input Frequency
Input Signal Level
Input Slew Rate
Input Duty Cycle
Self-Bias Voltage
Input Resistance
Input Capacitance
VCO
f
VCO
Frequency Range
LTC6948-1 (Note 3)
LTC6948-2 (Note 3)
LTC6948-3 (Note 3)
LTC6948-4 (Note 3)
LTC6948-1 (Notes 3, 4)
LTC6948-2 (Notes 3, 4)
LTC6948-3 (Notes 3, 4)
LTC6948-4 (Notes 3, 4)
l
l
l
l
l
l
l
l
l
elecTrical characTerisTics
CONDITIONS
l
MIN
10
0.5
20
TYP
MAX
425
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
5.8
1.85
8.4
14
2.25
11.6
V
kΩ
pF
Differential
Differential
l
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
100
–9
–6.1
–2.9
0.1
136
–7.3
–4.5
–1.4
1.5
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
P
RF-SE
Output Power, Single-Ended, f
RF
= 900MHz
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, O = 2 to 6
l
l
l
l
l
l
l
l
l
6.39
6
GHz
%
All Integers Included
l
175
–5.5
–2.8
0.2
3
–80
110
170
100
76.1
66.3
56.1
45.9
34.3
Ω
dBm
dBm
dBm
dBm
dBm
ns
ns
MHz
MHz
MHz
MHz
MHz
MHz
mA
%
%
%
%/V
ppm/°C
nA
Output Power, Muted, f
RF
= 900MHz
Mute Enable Time
Mute Disable Time
Phase/Frequency Detector
f
PFD
Input Frequency
Integer mode
Fractional mode
LDOEN = 0
LDOV = 3, LDOEN = 1
LDOV = 2, LDOEN = 1
LDOV = 1, LDOEN = 1
LDOV = 0, LDOEN = 1
8 Settings (See Table 6)
All Settings, V(CP) = V
CP+
/2
I
CP
= 1.0mA to 2.8mA, V(CP) = V
CP+
/2
I
CP
= 4.0mA to 11.2mA, V(CP) = V
CP+
/2
l
l
l
l
l
l
Charge Pump
I
CP
Output Current Range
Output Current Source/Sink Accuracy
Output Current Source/Sink Matching
1
11.2
±6
±3.5
±2
l
+
/2
Output Current vs Output Voltage Sensitivity (Note 5)
Output Current vs Temperature
Output Hi-Z Leakage Current
V(CP) = V
CP
I
CP
= 11.2mA, CPCLO = CPCHI = 0 (Note 5)
0.2
170
0.03
1
l
6948fa
For more information
www.linear.com/LTC6948
3
LTC6948
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
D+
= V
RF+
= 3.3V, V
CP+
= V
VCO+
= 5V unless otherwise
specified (Note 2). All voltages are with respect to GND.
SYMBOL
V
CLMP-LO
V
CLMP-HI
V
MID
R
N
PARAMETER
Low Clamp Voltage
High Clamp Voltage
Mid-Supply Output Bias Ratio
Divide Range
Divide Range
CONDITIONS
CPCLO = 1
CPCHI = 1, Referred to V
CP+
Referred to (V
CP+
– GND)
All Integers Included
All Integers Included, Integer Mode
All Integers Included, Fractional Mode
All Integers Included
LDO Enabled, Four Values
LDO Disabled
Required for LDO Stability
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
l
l
l
l
l
l
elecTrical characTerisTics
MIN
TYP
0.84
–0.96
0.48
MAX
UNITS
V
V
V/V
Reference (R) Divider
1
32
35
1
1.7 to 2.6
V
D+
0.047
1.55
0.8
250
±1
–3.3
2.0
3.4
±1
25
25
10
10
6
6
16
3.15
3.15
3.15
4.75
4.0
3.3
3.3
3.3
5.0
3.45
3.45
3.45
5.25
5.25
1500
22
60
35
1000
–1.9
0.1
1
31
1023
1019
262143
Counts
Counts
Counts
Counts
V
V
µF
V
V
mV
µA
mA
mA
µA
ns
ns
ns
ns
ns
ns
ns
V
V
V
V
V
µA
mA
mA
mA
µA
6948fa
VCO (N) Divider
l
l
Fractional ∆∑ Modulator
Numerator Range
Modulator LDO
Output Voltage
External Pin Capacitance
Digital Pin Specifications
V
IH
V
IL
V
IHYS
I
OH
I
OL
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 Figure 6 and Figure 7)
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
D+
Supply Range
V
RF
+
Supply Range
+
Supply Range
l
l
l
l
l
l
l
l
l
To V
IH
/V
IL
/Hi-Z with 30pF Load
l
Power Supply Voltages
l
l
l
l
l
V
VCO
V
CP+
Supply Range
Power Supply Currents
I
DD
I
CC(5V)
V
D+
Supply Current
Sum V
CP+
, V
VCO+
Supply Currents
Digital Inputs at Supply Levels, Integer Mode
l
l
Digital Inputs at Supply Levels, Fractional
Mode, f
PFD
= 66.3MHz, LDOV[1:0] = 3
I
CP
= 11.2mA
I
CP
= 1.0mA
PDALL = 1
l
l
l
18.2
48
26
450
4
For more information
www.linear.com/LTC6948
LTC6948
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
D+
= V
RF+
= 3.3V, V
CP+
= V
VCO+
= 5V unless otherwise
specified (Note 2). All voltages are with respect to GND.
SYMBOL
I
CC(3.3V)
PARAMETER
Sum V
REF+
, V
RF+
Supply Currents
CONDITIONS
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
elecTrical characTerisTics
MIN
TYP
70.4
81.1
91.3
109.2
114.8
119.6
53
–80
–130
–157
–77
–127
–156
–75
–126
–155
–73
–123
–154
–81
–132
–155
–84
–135
–156
–87
–138
–156
–89
–140
–157
–90
–141
–158
–226
–225
–274
–113
0.14
–98
MAX
80
95
105
125
135
140
250
UNITS
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
dBc/Hz
°RMS
dBc
Phase Noise and Spurious
L
VCO
VCO Phase Noise (LTC6948-1, f
VCO
= 3.0GHz, 10kHz Offset
f
RF
= 3.0GHz, OD[2:0] = 1 (Note 6))
1MHz Offset
40MHz Offset
VCO Phase Noise (LTC6948-2, f
VCO
= 4.0GHz, 10kHz Offset
f
RF
= 4.0GHz, OD[2:0] = 1 (Note 6))
1MHz Offset
40MHz Offset
VCO Phase Noise (LTC6948-3, f
VCO
= 5.0GHz, 10kHz Offset
f
RF
= 5.0GHz, OD[2:0] = 1 (Note 6))
1MHz Offset
40MHz Offset
VCO Phase Noise (LTC6948-4, f
VCO
= 6.0GHz, 10kHz Offset
f
RF
= 6.0GHz, OD[2:0] = 1 (Note 6))
1MHz Offset
40MHz Offset
VCO Phase Noise (LTC6948-3, f
VCO
= 5.0GHz, 10kHz Offset
f
RF
= 2.50GHz, OD[2 :0] = 2 (Note 6))
1MHz Offset
40MHz Offset
VCO Phase Noise (LTC6948-3, f
VCO
= 5.0GHz, 10kHz Offset
f
RF
= 1.667GHz, OD[2 :0] = 3 (Note 6))
1MHz Offset
40MHz Offset
VCO Phase Noise (LTC6948-3, f
VCO
= 5.0GHz, 10kHz Offset
f
RF
= 1.25GHz, OD[2 :0] = 4 (Note 6))
1MHz Offset
40MHz Offset
VCO Phase Noise (LTC6948-3, f
VCO
= 5.0GHz, 10kHz Offset
f
RF
= 1.00GHz, OD[2 :0] = 5 (Note 6))
1MHz Offset
40MHz Offset
VCO Phase Noise (LTC6948-3, f
VCO
= 5.0GHz, 10kHz Offset
f
RF
= 0.833GHz, OD[2 :0] = 6 (Note 6))
1MHz Offset
40MHz Offset
L
NORM(INT)
L
NORM(FRAC)
L
1/f
Integer Normalized In-Band Phase Noise
Floor
Fractional Normalized In-Band Phase Noise
Floor
Normalized In-Band 1/f Phase Noise
In-Band Phase Noise Floor
Integrated Phase Noise from 100Hz to
40MHz
Spurious
INTN = 1, I
CP
= 5.6mA (Notes 7, 8, 10)
INTN = 0, CPLE = 1, I
CP
= 5.6mA
(Notes 7, 8, 10)
I
CP
= 11.2mA (Notes 7, 11)
Fractional Mode, CPLE = 1
(Notes 7, 9, 10, 12)
Fractional Mode, CPLE = 1 (Notes 9, 12)
Fractional Mode, f
OFFSET
= f
PFD
, PLL locked
(Notes 8, 13, 14)
Note 1:
Stresses beyond those listed under Absolute Maximum Ratings
may cause permanent damage to the device. Exposure to any Absolute
Maximum Rating condition for extended periods may affect device
reliability and lifetime.
Note 2:
The LTC6948I is guaranteed to meet specified performance limits
over the full operating junction temperature range of –40°C to 105°C.
6948fa
For more information
www.linear.com/LTC6948
5
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