RF7115_1 Datasheet, PDF (11/22 Pages) RF Micro Devices – QUAD-BAND GSM850/GSM900/DCS/PCS TRANSMIT MODULE

RF7115
Theory of Operation
Product Description
The RF7115 is a high-power, high-efficiency, transmit module (TXM) with fully-integrated power control functionality, harmonic
filtering, band selectivity, and TX/RX switching. The TXM is self-contained, with 50Ω I/O terminals with four RX ports allowing
true quad band operation. The power control function eliminates all power control circuitry, including directional 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 provides 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 compliant harmonic suppression at the antenna
port even under high mismatch conditions, which is important as modern antennas today often present a load that signifi-
cantly deviates from nominal impedance.
Overview
The RF7115 is a true quad-band GSM850, EGSM900, DCS1800, and PCS1900 power amplifier module with fully integrated
power control functionality, harmonic filtering, band selectivity and TX/RX switching. This simplifies the phone design by elimi-
nating 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 baseband circuit. The module has 4
Rx ports for GSM850. EGSM900, DCS1800, and PCS1900 bands of operation. For optimum 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
0
0
0
0
0
1
1
B1 B2 B3
0
0
0
0
0
1
1
0
x
0
1
x
1
1
x
x
0
1
x
1
1
TX Module Mode
Stand by mode
RX 1
RX 2
RX 3
RX 4
TX low band (GSM850/EGSM900)
TX high band (DCS1800/PCS1900)
Rev A0 DS060808
7628 Thorndike Road, Greensboro, NC 27409-9421 · For sales or technical
support, contact RFMD at ([phone] or [e-mail].
11 of 22