LDMOS RF IC Amplifiers Boost 100 W At 900 MHz

April 12, 2007
These two-stage integrated-circuit amplifiers achieve discrete-device-like output power for GSM and EDGE base stations at 869 to 960 MHz and 1805 to 1880 MHz.

High output-power levels are generally considered the demesne of discrete transistors, and certainly beyond the reach of integrated circuits (ICs). But the latest LDMOSbased radio-frequency IC (RF IC) amplifiers from Freescale Semiconductor (www.freescale.com/rfpower) will force designers to change their thinking on ICs and power, since these over-molded plastic-packaged amplifiers can generate 100 W output power from 869 to 960 MHz and from 1805 to 1880 MHz. The firm's models MWE6IC9100N and MW7IC18100N two-stage RF IC amplifiers cover the 869-to-960-MHz and 1805-to-1880-MHz frequency ranges, respectively, with 100 W of Class AB output power.

Model MWE6IC9100N offers better than 100 W output power at 1-dB compression in the 869-to-894-MHz cellular band and the 920-to-960MHz GSM band. Designed for supplies from +26 to +32 VDC, it is built to work with the types of modulated signals found in GSM and GSM EDGE base stations. With a +26-VDC supply, the RF IC amplifier draws 120 mA current for stage one and 950 mA current for stage 2 under GSM signal conditions while delivering the 100W CW output power. For the same supply and under GSM EDGE signal conditions, it draws 230 mA current for the first stage and 870 mA current for the second stage in achieving 50 W average output power.

When evaluated in a Freescale test fixture in a 50-ohm test system under GSM signal conditions, the power gain ranges from 31 to 36 dB, with typical power gain of 33.5 dB at 960 MHz. The input return loss at that frequency is typically 15 dB and the power-added efficiency is typically 54 percent and no less than 52 percent. The output power at 1-dB compression at 960 MHz is at least 100 W and typically 112 W CW. Under typical GSM EDGE signal conditions (50-W average output power, running at +28 VDC from 869 to 894 MHz and 920 to 960 MHz with EDGE modulation), the power-added efficiency is typically 35.5 percent while the error-vector-magnitude (EVM) performance is typically 2 percent root mean square (RMS). The spectral regrowth at a 400-kHz offset frequency is typically 63 dBc while at a 600kHz offset frequency is typically 81 dBc.

With similar performance but at higher frequencies, model MW7IC18100N provides more than 100 W output power at 1-dB compression over the 1805 to 1880 MHz and 1930to-1990-MHz Personal Communications Services (PCS) bands with 30 dB gain and 48 percent PAE when operating under GSM conditions at +28 VDC. Spectral regrowth under GSM EDGE conditions (+28 VDC and 215 mA) with 40W output power from 1805 to 1880 MHz and 1930 to 1990 MHz is 63 dBc offset 400 kHz from the carrier and 80 dBc offset 600 kHz from the carrier. The EVM performance under GSM EDGE conditions is 1.5 percent.

Both RF IC amplifiers feature integrated electrostatic-discharge (ESD) protection. Both devices are supplied in plastic (TO-270 or TO-272) packages capable of withstanding temperatures to +200C, and both devices are RoHS compliant. Both power RF ICs are already internally impedance matched to 50 ohms for ease of use in high-frequency circuits, and both amplifier RF ICs are capable of handling a load mismatch equivalent to a 5.0:1 VSWR. The RF IC amplifiers can be supplied in tape-and-reel format for use with automated assembly equipment. The RF IC amplifiers are designed to work with the firm's extensive line of general-purpose amplifiers (GPAs) as the driver stage (see Microwaves & RF, March 2007, p. 104).

Freescale Semiconductor, Inc., 2100 East Elliot Rd., Tempe, AZ 85284; Internet: www.freescale.com/rfpower

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