Multiband Linear Power Amplifiers

ITS Electronics Inc.
Concord, Ontario, Canada

A family of wideband linear power amplifiers have been developed to service cellular/PCS applications as well as electronic warfare (EW)/electronic countermeasures (ECM), local multipoint distribution service and active load pull applications. The amplifier models cover four basic frequency ranges (0.8 to 2 GHz, 1.8 to 3.8 GHz, 6 to 18 GHz and 24 to 31 GHz) and are provided in various power output levels from 10 to 100 W at the lower frequency bands to 0.1 to 2 W at the higher bands. These power amplifiers are class A GaAs FET-type configurations that set new price and performance standards for wideband power and reliability.

In the 0.8 to 2 GHz frequency range, the model PA0820-4030M power amplifier provides 10 W of output power at the 1 dB compression point (P1dB) and a third-order intercept point (IP3 ) of 50 dBm. The amplifier features a gain of 30 dB (min) and a gain flatness of ± 0.7 dB, as shown in Figure 1 . Harmonic and spurious levels at P1dB are -38 and -64 dBc, respectively, and intermodulation distortion from a two-tone signal at 34 dBm is -30.8 dBc, as shown in Figure 2 . The amplifier operates from a ±12 V DC supply.

The model PA-1A2-001 amplifier also operates over the 0.8 to 2 GHz frequency range and is rated for 50 W power output at P1dB and 55 W at saturation. Gain is 47 dB at rated power with a gain flatness of ±1.5 dB. The amplifier features low harmonic levels, a high IP3 and high efficiency and dynamic range. Minimum in-band and out-of-band harmonic levels are -25 and -40 dBc, respectively, at P1dB. Spurious levels are -70 dBc and the amplifier is unconditionally stable for all phases of an infinite-load SWR. The amplifier accepts input signals of +10 dBm or less consisting of CW, AM, FM, or pulse or phase modulation.

In addition, the unit contains a thermal shutdown feature that continuously monitors the base plate temperature and automatically disables the amplifier and provides a visual front-panel alarm if the base plate temperature exceeds the factory-preset limit. An internal fan provides sufficient cooling to ensure low device junction temperatures and high mean time between failures. The power amplifier utilizes type N female front-panel input and output connectors and is contained in a 3U 19" rack-mounted housing measuring 5.25" x 19.00" x 21.00". Applications for the model PA-1A2-001 linear power amplifier include communication, instrumentation, electromagnetic compatibility, EW and ECM applications as well as intermodulation and device testing.

An additional series of linear power amplifiers are available that span the 1.8 to 3.8 GHz frequency range for use in harmonic load pull and EW applications. The amplifiers are available at P1dB power levels of 2, 10 and 40 W. The models PA1838-4040 and PA1838-4640 are 10 and 40 W power amplifiers, respectively, that are specifically designed for harmonic load pull applications. Figure 3 shows an internal view of the model PA1838-4640 amplifier module. Both PCS fundamental and first harmonic frequencies can be matched using these units. This technique provides the device manufacturer and amplifier designer with optimum data to effect an efficient PCS amplifier design. The amplifiers are available as modules or integrated in a 19" rack-compatible shelf complete with power supply and digital interface card compatible with all standard interface protocols.

The broadband power amplifier family is further extended in frequency with amplifiers in the 6 to 18 GHz frequency range featuring power outputs of 2 to 4 W. These amplifiers are targeted primarily for EW and phased-array transmit/receive module testing. The units use a mixture of discrete devices and MMICs, and have been field proven in airborne environments. The model PA-618-3535 amplifier is representative of this group, producing +35 dBm output at P1dB over the 6 to 18 GHz range. The amplifier features a gain of greater than 35 dB, noise figure of less than 10 dB and IP3 of greater than 40 dBm. The unit operates from ±15 V DC over a temperature range of 0° to +50°C and contains SMA female input and output connectors. Figure 4 shows the amplifier's Pout vs. Pin .

As an answer to the growing need for local multipoint distribution and cellular system and Ka-band satellite communications terminals, a family of power amplifiers also have been developed that deliver from 0.1 to 2 W in the 24 to 31 GHz frequency range. These amplifiers have an instantaneous bandwidth of 1 GHz (min). The model PA2930-3030 power amplifier is a 1 W unit covering the 29.5 to 30.5 GHz range. The amplifier features a small-signal gain of 30 dB, gain flatness of ±1.5 dB and harmonic levels of -25 dBc at P1dB. The unit operates from ±12 V DC at a nominal current of 3.5 A (max). The amplifier utilizes K-type input and output connectors and is supplied in a 2.2" x 1.6" x 0.5" housing. Figures 5 and 6 show the amplifier's frequency response at P1dB and Pout vs. Pin, respectively. The 1 W amplifier can be used as a stand-alone component in a transmitter or transceiver, or as a driver for a traveling-wave tube or klystron power amplifier.

Additional linear power amplifiers within the same frequency ranges, including S-band units for wireless local loop applications and narrowband versions, also are available. These amplifiers utilize innovative manufacturing techniques to ensure repeatability, reproducibility and competitive cost.

ITS Electronics Inc.,
Concord, Ontario, Canada
(905) 660-0405.