RF137 查看數據表（PDF） - Conexant Systems

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RF137

Transceiver For GSM Applications

Conexant Systems 

Transceiver

There are two frequency synthesizers on the chip, one UHF and

one VHF. The UHF synthesizer can provide frequencies from

500 MHz to 2 GHz. It consists of a 32/33 modulus prescaler, a

13-bit R counter, an 18-bit N counter, a phase detector with lock

detection, and a charge pump. The VHF synthesizer, with a

frequency range from 150 MHz to 450 MHz, consists of an 8/9

modulus prescaler, a 13-bit R counter, a 16-bit N counter, a

phase detector with lock detection, and a charge pump. Each

synthesizer has four charge pump current settings for optimal

performance.

The on-chip oscillator together with a few external components

as resonant elements, form a VHF VCO (Figure 3 shows the

VCO configuration). The differential VCO output is buffered and

then fed to three dividers (Rx, Tx, Sx) with a selectable divide

ratio of either 2 or 4. The Rx and Tx dividers are both

quadrature dividers, which generates in-phase and quadrature

phase LOs.

The on-chip oscillator with the on-chip VHF synthesizer,

provides complete VHF frequency synthesis for the Rx VHF LO

and Tx VHF LO.

The three-wire bus control allows the RF137 to be optimized for

any desired frequency plan. It also programs the two on-chip

RF137

frequency synthesizers. To ensure that the data remains

latched, one of the signals TXENA, RXENA, or SXENA must

stay enabled.

When bit C0 is set to 1, it allows for divider selections in the

translation loop, high-side/low-side injection for the image reject

mixer and the receive IF amplifiers’ gain setting. When bit C0 is

set to 0, it programs the UHF/VHF synthesizer, the R/N counter,

charge pump polarity, charge pump output current, and

prescaler setting.

The three-wire bus timing diagram is provided in Figure 4.

Figure 5 illustrates a typical RF137 application circuit. Figure 6

provides the package dimensions for the 48-pin TQFP RF137

transceiver and Figure 7 provides the tape and reel dimensions.

ESD Sensitivity

Because the RF137 is a static-sensitive electronic device,

proper ESD precautions must be taken when using the RF137.

Do not operate or store the RF137 near strong electrostatic

fields.

VCC

Vtune

External

Resonator

RES1

(pin 33)

RES2

(pin 32)

RF137

100777C

C588

Figure 3. RF137 Internal VCO

Conexant - Proprietary

Data Subject to Change

9

October 11, 2000

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