RF2705GPCBA-41X View Datasheet(PDF) - RF Micro Devices

Part Name

Description

MFG CO.

RF2705GPCBA-41X

LOW NOISE, MULTI-MODE, QUAD-BAND, QUADRATURE MODULATOR AND PA DRIVER

RF Micro Devices 

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Pin Function Description

1

VCC2

Supply for LO buffers, frequency doubler and dividers.

RF2705G

Interface Schematic

VCC2

Modulator and

VGA

2

LO HB P High band local oscillator input (1800MHz).

In “low band FLO/2” modes the signal (LOHBP-LOHBN) undergoes a fre-

quency division of 2 to provide the low band LO signal for the modulator.

In “high band FLOx1” modes the signal (LOHBP-LOHBN) is used as the

high band LO signal for the modulator.

VCC

In “high band bypass” a modulated DCS1800/PCS1900 signal (LOHBP-

LOHBN) is switched into the RF signal path. The modulator is disabled and

the signal is routed to the RFOutHb outputs through a differential PA driver

amplifier.

The LOHBP input is AC-coupled internally.

The noise performance, carrier suppression at low output powers and side- LO HB P

band suppression all vary with LO power. The optimum LO power is

between -3dBm and +3dBm. The device will work with LO powers as low as

-20dBm however this is at the expense of higher phase noise in the LO cir- LO HB N

cuitry and poorer sideband suppression.

The input impedance should be externally matched to 50Ω. The port can

be driven either differentially or single ended. The port impedance does

not vary significantly between active and power down modes.

The RF2705 is intended for use with the RF6002. This performs the GSM

GMSK modulation within a Frac-N synthesizer loop. The 8PSK EDGE and

W-CDMA signal modulations are performed in the RF2705 and uses the

RF6002’s synthesizers to generate the LO signals. The LO signal for

EDGE900 mode is derived by frequency division by 2 of the RF6002’s

DCS1800 VCO. This helps protect the system against PA pulling.

3

LO HB N The complementary LO input for both LOHBP LO signals.

See pin 2.

In any of the modes the LOHB input may be driven either single ended or

differentially. If the LO is driven single ended then the PCB board designer

can ground this pin.

It is recommended that if this pin is grounded that it is kept isolated from

the GND1 pin and the die flag ground. All connections to any other ground

should be made through a ground plane. Poor routing of this ground signal

can significantly degrade the LO leakage performance.

Rev A0 DS060206

7628 Thorndike Road, Greensboro, NC 27409-9421 · For sales or technical

support, contact RFMD at (+1) 336-678-5570 or sales-support@rfmd.com.

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