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GPAs Extend Linear Gain To 6 GHz

These broadband amplifiers run on a single +5-VDC supply and combine high intercept points with low noise figures to excel in applications requiring good linearity.

General-purpose amplifiers (GPAs) are among the most versatile of active components. They can be used wherever gain is needed and signal losses must be overcome. These devices can be used as buffer amplifiers to create isolation between devices. Freescale Semiconductor (Tempe, AZ) has increased the usefulness of its own GPA line by adding four linear Class A devices with frequency coverage to 6 GHz to its GPA product lineup. The RF power devices are internally matched to 50 ohms for ease of installation in RF and microwave circuits and systems.

The new GPA additions include the model MMH3111N, the firm's first GaAs heterostructure-field-effect-transistor, and the InGaP heterojunction-bipolar-transistor (HBT) devices MMG3014N, MMG3015N, and MMG3016N (see table). All of the GPAs are supplied in SOT-89 plastic packages and are designed for a single positive supply of +5 VDC.

Both HFETs and HBTs provide extremely good linearity and reliability. In fact, the HFET technology is meant to provide wide dynamic range in terms of lower distortion than an HBT at the same bias current with higher associated output third-order intercept point (OIP3). As a case in point, the MMH3111N operates from 250 MHz to 3 GHz with OIP3 of +41 dBm and noise figure of 3.7 dB. It achieves +21.5 dBm output power with 11.5 dB gain at 2.14 GHz. The amplifier draws 150 mA current from a +5-VDC supply.

In contrast, the three InGaP HBTs feature DC-coupled performance with nearly the same upper limit to the dynamic range (OIP3), but with somewhat higher noise figure. The MMG3014N, for example, offers an OIP3 of +40.5 dBm with noise figure of 4 dB across the frequency range from DC to 4 GHz. Because of the high OIP3, it draws a similar amount of current as the HFET amplifier, with 160 mA current consumed from a single +5-VDC supply. The amplifier achieves 20 dB gain at 900 MHz with +24 dBm output power at P1-dB compression.

The MMG3015N offers the widest frequency coverage of the group, with range of DC to 6 GHz. It has an OIP3 of +37 dBm with noise figure of 4.5 dB. The decreased OIP3 results in less current draw than the other devices, with typically 95 mA current consumed from a single +5-VDC supply. The GPA generates 15.5 dB small-signal gain at 2.14 GHz with +21.5 dBm output power at 1-dB compression.

The MMG3016N features OIP3 of +40.5 dBm and 4.5 dB noise figure from DC to 4 GHz. As expected, the current draw is higher, at 160 mA from a +5-VDC supply, which results in output power of 0.25 W (+24 dBm) with 15-dB gain at 1-dB compression at 900 MHz. The devices feature low thermal resistance for long operating lifetimes.

The GPAs are designed to run from a single-voltage supply without external resistors. They are all RoHs compliant and well suited for both commercial and military applications, including predriver and driver amplifiers for wireless base-station amplifiers.

Freescale Semiconductor, Inc., 2100 East Elliot Rd., Tempe, AZ 85284; Internet:

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