Adding gain to a high-frequency circuit is often as simple as designing in an integrated-circuit (IC) amplifier. But when more gain and power is needed for a specific frequency range, it is usually preferable to work with a power transistor chip, developing impedance-matching networks suited to the frequency range of interest. For those in need of discrete transistor chips rather than ICs, the BCP series GaAs pseudomorphic-high-electron-mobility-transistor (pHEMT) chips from BeRex (www.berex.com) are supplied in bare-die form. The series features a wide range of device sizes for low-noise, high-gain, and medium-output-power from about 100 MHz to about 26.5 GHz. They can be impedance matched according to a customer’s requirements, either for narrowband or broadband uses.

The BeRex pHEMT chips are fabricated with nominal quarter-micron gate length and a number of different gate widths (for different output-power levels) ranging from 200 to 2400 microns (see table). The smallest device is model BCP020T, with 200-μm gate width that yields typical 0.25-W (+24 dBm) output power at 1-dB compression when tuned for power and tested at either 12 or 18 GHz with drain-source voltage of +8 VDC and about 30 mA drain-source current (or 50% of the typical saturated drain-source-current rating). Under those same conditions, it provides 14-dB gain at 12 GHz and 12-dB gain at 18 GHz. It can also be tuned for gain (with +21 dBm output power) to achieve typical 17-dB gain at 12 GHz and 13-dB gain at 18 GHz. The chip is also suitable for low-noise-amplifier (LNA) applications, with a noise figure of typically 1.09 dB at 12 GHz. As with the other BeRex pHEMT chips, the BCP020T boasts impressive power-added efficiency—typically 60% at 12 GHz and 55% at 18 GHz—tested under the same conditions as for output power.

The largest of the BCP series GaAs pHEMT chips is model BCP240T, with a gate width of 2400 μm for the highest output power of the series—typically +34.8 dBm at 12 GHz and +33.7 dBm at 18 GHz when impedance matched for power (drain-source voltage of +8 VDC and drain-source current of about 360 mA). The gain under those matching conditions is 10.2 dB at 12 GHz and 7.7 dB at 18 GHz. When the chip is tuned for gain, the levels increase to 11.0 dB at 12 GHz and 8.7 dB at 18 GHz, with the output power dropping to +32.5 dBm at 12 GHz and +31.2 dBm at 18 GHz. When tuned for power, the PAE is 58% at 12 GHz and 42% at 18 GHz. When tuned for gain, the PAE is 36% at 12 GHz and 27% at 18 GHz.

In between these two devices, the BCP series includes transistor chips such as the BCP080T with 800-micron gate width and the BCP160T with 1600-micron gate width. The former can provide typically 1 W (+30 dBm) output power at 12 and 18 GHz when tuned for power, with associated gains of 10.4 and 6.7 dB at 12 and 18 GHz, respectively. The latter generates typically 2 W (+33 dBm) output power at 12 and 18 GHz, with associated gains of 10.4 and 6.7 dB at 12 and 18 GHz, respectively, when tuned for power. Under those conditions, the PAE for the BCP080T is typically 60% at 12 GHz and typically 55% at 18 GHz, while for the BCP160T, the PAE is typically 63% at 12 GHz and typically 47% at 18 GHz.

All of the BCP series GaAs pHEMT chips employ recessed gates with silicon nitride (Si3N4) passivation for high reliability. All are designed and manufactured in the United States on 100-micron-thick substrates and are suited for a wide range of applications in commercial, military, and test-and-measurement systems. As Dr. Alex Yoo, BeRex’s Vice-President of Research and Development, has noted: “BeRex, Inc. is committed to being a dominate player in providing high performance PHEMT devices. Our company’s Silicon Valley location has allowed us to assemble a ‘dream team’ of highly experienced PHEMT designers, quality and applications engineers, all of whom are focused on providing our clients with the highest quality parts, consistently and reliably.”

BeRex, Inc.
1735 N. 1st St., #302
San Jose, CA 95112
(408) 452-5595