LTC6946_15 Datasheet, PDF (1/32 Pages) Linear Technology – Ultralow Noise and Spurious 0.37GHz to 6.39GHz Integer-N Synthesizer with Integrated VCO

LTC6946
Ultralow Noise and Spurious
0.37GHz to 6.39GHz Integer-N
Synthesizer with Integrated VCO
Features
Description
nn _{Low Noise Integer-N PLL with Integrated VCO}
nn _{–226dBc/Hz Normalized In-Band Phase Noise Floor}
nn _{–274dBc/Hz Normalized In-Band 1/f Noise}
nn _{–157dBc/Hz Wideband Output Phase Noise Floor}
nn _{Excellent Spurious Performance}
nn _{Output Divider (1 to 6, 50% Duty Cycle)}
nn _{Output Buffer Muting}
nn _{Low Noise Reference Buffer}
nn _{Charge Pump Current Adjustable from 250µA to}
11.2mA
nn _{Configurable Status Output}
nn _{SPI Compatible Serial Port Control}
nn _{PLLWizard™ Software Design Tool Support}
Applications
nn _{Wireless Base Stations (LTE, WiMAX, W-CDMA, PCS)}
nn _{Broadband Wireless Access}
nn _{Military and Secure Radio}
nn _{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.
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
Typical Application
5V
15Ω
0.01µF
5.7GHz Wideband Receiver
4.7nF
2.2µF
57nF
97.6Ω
0.01µF
3.3V
0.01µF
3.3V
0.01µF
1µF
+
1µF
10MHz 51.1Ω
GND
V_CP+
CP
V_REF+
REF⁺
REF^–
LTC6946-3
3.3V
0.1µF
SPI BUS
BB
V_RF+
RF⁺
RF^–
GND
MUTE
1µF
0.01µF
3.3V
0.1µF
68nH
68nH
RF INPUT
SIGNAL
3.3V
100pF
RF
LO IF
TO IF
PROCESSING
100pF
50Ω
6946 TA01a
UNUSED OUTPUT
IS AVAILABLE
FOR OTHER USE
For more information www.linear.com/LTC6946
LTC6946-3 PLL Phase Noise
–80
–90
–100
–110
–120
–130
RMS NOISE = 0.61°
–140 _{RMS JITTER = 296fs}
–150
–160
f_RF = 5.7GHz
f_PFD = 10MHz
BW = 85kHz
100 1k 10k 100k 1M
OFFSET FREQUENCY (Hz)
10M 40M
6946 TA01b
6946fb
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