LMX2487E

更新时间： 2024-11-21 03:54:15

品牌	Logo	应用领域
美国国家半导体 - NSC		/
页数	文件大小	规格书
38页	733K
描述
7.5 GHz High Performance Delta-Sigma Low Power Dual PLLatinum⑩ Frequency Synthesizers with 3.0 GHz Integer PLL

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LMX2487E 数据手册

May 2007

LMX2487E

7.5 GHz High Performance Delta-Sigma Low Power Dual

PLLatinum™ Frequency Synthesizers with 3.0 GHz Integer

PLL

WLAN Standards

■

General Description

The LMX2487E is a low power, high performance delta-sigma

Features

fractional-N PLL with an auxiliary integer-N PLL. It is fabricat-

ed using National Semiconductor’s advanced process.

Quadruple Modulus Prescalers for Lower Divide Ratios

With delta-sigma architecture, fractional spurs at lower offset

frequencies are pushed to higher frequencies outside the loop

bandwidth. The ability to push close in spur and phase noise

RF PLL: 16/17/20/21 or 32/33/36/37

■

IF PLL: 8/9 or 16/17

■

energy to higher frequencies is a direct function of the mod-

ulator order. Unlike analog compensation, the digital feed-

back technique used in the LMX2487E is highly resistant to

changes in temperature and variations in wafer processing.

The LMX2487E delta-sigma modulator is programmable up

to fourth order, which allows the designer to select the opti-

mum modulator order to fit the phase noise, spur, and lock

time requirements of the system.

Advanced Delta Sigma Fractional Compensation

12 bit or 22 bit selectable fractional modulus

■

Up to 4th order programmable delta-sigma modulator

Features for Improved Lock Times and Programming

Fastlock / Cycle slip reduction

■

Integrated time-out counter

Serial data for programming the LMX2487E is transferred via

a three line high speed (20 MHz) MICROWIRE interface. The

LMX2487E offers fine frequency resolution, low spurs, fast

programming speed, and a single word write to change the

frequency. This makes it ideal for direct digital modulation

applications, where the N counter is directly modulated with

information. The LMX2487E is available in a 24 lead

4.0 X 4.0 X 0.8 mm LLP package.

Single word write to change frequencies with Fastlock

Wide Operating Range

LMX2487E RF PLL: 3.0 GHz to 7.5 GHz

■

Useful Features

Digital lock detect output

■

Hardware and software power-down control

On-chip crystal reference frequency doubler.

Applications

RF phase comparison frequency up to 50 MHz

Cellular phones and base stations

■

2.5 to 3.6 volt operation with I_CC= 8.5 mA at 3.0 V

■

Direct digital modulation applications

Satellite and cable TV tuners

Functional Block Diagram

30013901

PLLatinum™ is a trademark of National Semiconductor Corporation.

300139

www.national.com

12 3 4 5 6 7...38

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与LMX2487E相关器件

型号	品牌	获取价格	描述	数据表
LMX2487ESQ	NSC	获取价格	7.5 GHz High Performance Delta-Sigma Low Powe
LMX2487ESQ/NOPB	TI	获取价格	用于射频个人通信的 3GHz 至 7.5GHz Δ-Σ 低功耗双路 PLL \| RTW \|
LMX2487ESQE/NOPB	TI	获取价格	Delta-Sigma Low Power Dual PLL for RF Personal Communications 24-WQFN -40 to 85
LMX2487ESQX	NSC	获取价格	7.5 GHz High Performance Delta-Sigma Low Powe
LMX2487ESQX/NOPB	TI	获取价格	Delta-Sigma Low Power Dual PLL for RF Personal Communications 24-WQFN -40 to 85
LMX2487ESQX/NOPB	NSC	获取价格	IC PLL FREQUENCY SYNTHESIZER, 7500 MHz, PQCC24, 4 X 4 MM, 0.80 MM HEIGHT, LEAD FREE, LLP-2
LMX2487SQ	TI	获取价格	Low-Power Dual PLLatinum Frequency Synthesizers
LMX2487SQ	NSC	获取价格	3.0 GHz - 6.0 GHz High Performance Delta-Sigma Low Power Dual PLLatinum? Frequency Synthes
LMX2487SQ/NOPB	TI	获取价格	Low-Power Dual PLLatinum Frequency Synthesizers
LMX2487SQX	NSC	获取价格	3.0 GHz - 6.0 GHz High Performance Delta-Sigma Low Power Dual PLLatinum? Frequency Synthes

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