LTC6946

1

6946fa

TYPICAL APPLICATION

FEATURES

DESCRIPTION

Ultralow Noise and Spurious

0.37GHz to 5.7GHz Integer-N

Synthesizer with Integrated VCO

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.

LTC6946-3 PLL Phase Noise

APPLICATIONS

11.2mA

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.

OFFSET FREQUENCY (Hz)

–140

–130

–110

–90

–80

100

10k

100k

10M 40M

6946 TA01b

–150

1k

1M

–100

–120

–160

RMS NOISE = 0.61°

RMS JITTER = 296fs

BW = 85kHz

GND

CP

BB

+

GND

MUTE

LTC6946-3

0.01μF

0.01μF

2.2μF

0.01μF

100pF

0.01μF

68nH

68nH

1μF

3.3V

3.3V

4.7nF

57nF

100pF

UNUSED OUTPUT

IS AVAILABLE

FOR OTHER USE

RF INPUT

SIGNAL

TO IF

PROCESSING

LO

IF

RF

0.01μF

470pF

0.1μF

0.1μF

3.3V

6946 TA01a

3.3V

3.3V

+

470pF

51.1Ω

50Ω

SPI BUS

10MHz

15Ω

97.6Ω

5V

Frequency Coverage Options

LTC6946-1

LTC6946-2

LTC6946-3

VCO Frequency (GHz) 2.240 to 3.740

3.080 to 4.910

3.840 to 5.790

O DIV = 1

2.240 to 3.740

3.080 to 4.910

3.840 to 5.790

O DIV = 2

1.120 to 1.870

1.540 to 2.455

1.920 to 2.895

0 DIV = 3

0.747 to 1.247

1.027 to 1.637

1.280 to 1.930

O DIV = 4

0.560 to 0.935

0.770 to 1.228

0.960 to 1.448

O DIV = 5

0.448 to 0.748

0.616 to 0.982

0.768 to 1.158

O DIV = 6

0.373 to 0.623

0.513 to 0.818

0.640 to 0.965

5.7GHz Wideband Receiver