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HMC703LP4E

v02.0813

8 GHz fractional syntHesizer

For price, delivery and to place orders: Hittite Microwave Corporation, 2 Elizabeth Drive, Chelmsford, MA 01824

978-250-3343 • 978-250-3373 fax • Order On-line at www.hittite.com

Application Support: pll@hittite.com

Required CP Offset = (2.5 ∙ 10-9+ 4TPS) ∙ (Fcomparison) ∙ ICP where:

TPS: is the RF period at the fractional prescaler input

ICP: is the full scale current setting of the switching charge pump

Note that this calculation can be performed for the center frequency of the VCO, and does not need refinement for small

differences (<25%) in center frequencies. Also, operation with unreasonably large charge pump offset may cause Lock

Detect to incorrectly indicate an unlocked condition. To correct, reduce the offset to recommended levels.

Another factor in Fractional spectral performance is the choice of the Delta-sigma Modulator mode. Mode B is normally

recommended, as it allows higher PD frequencies and makes it easier to filter the fractional quantization noise. For low

prescaler frequencies (<1.5GHz), however, mode A can offer better in-band spectral performance. see Reg 06h[0] for

DsM mode selection. Finally, all fractional synthesizers create fractional spurs at some level. Hittite offers the lowest

level fractional spurious in the industry in an integrated solution.

operational Modes

The HMC703LP4E can operate in a eight of different modes (Reg 06h[7:5]), and supports “Triggering” from 3 different

sources. The modes of operation include:

“Integer Mode”

“Fractional Mode”

“Exact Frequency Mode”

Frequency Modulation “FM Mode”

Phase Modulation “PM Mode”

“Frequency sweep Mode” (3 types)

All modes require Fractional mode to be enabled except for Integer mode. Fractional mode allows fine frequency

steps. Exact Frequency mode allows precise fractional frequency steps with zero frequency error. FM and PM modes

can be used for simple communications links, with data rate limitations set by the loop filter bandwidth. The PM mode

also allows for precise incremental phase adjustments, which can be important in phased arrays and other systems.

Frequency sweep supports built-in one-way, two-way, or user defined frequency sweeps, useful in FMCW radar

applications.

Depending on the mode, the auxiliary registers Reg 0Ah, Reg 0Ch and Reg 0Dh are used for different functions, as

shown in Table 6.

(eQ 4)

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responsibility is assumed by Analog Devices for its use, nor for any infringements of patents or other

rights of third parties that may result from its use. Specifications subject to change without notice. No

license is granted by implication or otherwise under any patent or patent rights of Analog Devices.

Trademarks and registered trademarks are the property of their respective owners.

For price, delivery, and to place orders: Analog Devices, Inc.,

One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106

Phone: 781-329-4700 • Order online at www.analog.com

Application Support: Phone: 1-800-ANALOG-D

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