RF7115 datasheet(11/22 Pages) RFMD

11 / 22 page

11-375

RF7115

Rev A0 060808

Theory of Operation

Product Description

The RF7115 is a high-power, high-efficiency, transmit module (TXM) with fully-integrated power control functionality, har-

monic filtering, band selectivity, and TX/RX switching. The TXM is self-contained, with 50

Ω I/O terminals with four RX

ports allowing true quad band operation. The power control function eliminates all power control circuitry, including direc-

tional couplers, diode detectors, and power control ASIC’s, etc. The power control capability provides 50dB continuous

control range, and 70dB total control range, using a DAC-compatible, analog voltage input. The TX Enable feature pro-

vides for PA activation (TX mode) or RX mode/Stand-by. Internal switching provides a low-loss, low-distortion path from

the Antenna port to the TX path (or RX port), while maintaining proper isolation. Integrated filtering provides ETSI com-

pliant harmonic suppression at the antenna port even under high mismatch conditions, which is important as modern

antennas today often present a load that significantly deviates from nominal impedance.

Overview

The RF7115 is a true quad-band GSM850, EGSM900, DCS1800, and PCS1900 power amplifier module with fully inte-

grated power control functionality, harmonic filtering, band selectivity and TX/RX switching. This simplifies the phone

design by eliminating the need for the complicated control loop design, harmonic filters, TX/RX switch and possible

matching components between these. The power control loop can be driven directly from the DAC output in the base-

band circuit. The module has 4 Rx ports for GSM850. EGSM900, DCS1800, and PCS1900 bands of operation. For opti-

mum performance, it is best to use Rx1 and Rx2 for low band, and Rx3 and Rx4 for high band operation. Best forward

isolation can be achieved in these states during the off mode as well. To control the mode of operation, there are four

logic control signals; TX Enable, B1, B2, and B3. Refer to truth table below for mode of operations. If control signals are

limited, eliminate the use of the standby mode and B3 may remain in the high state for all modes of operation. By also

changing the don’t care state (X) of B1 allows minimum control logic switching between on and off states.

Module Control and Antenna Switch Logic

TX_EN

TX Module Mode

Stand by mode

RX 1

RX 2

RX 3

RX 4

TX low band (GSM850/EGSM900)

TX high band (DCS1800/PCS1900)

RF7115 Datasheet(PDF) 11 Page - RF Micro Devices