Figure 1. The Amplifier Is Packaged in a WR5 waveguide module, with electric-field-plane alumina probes to interface the chip to the waveguide, and bypass capacitors to suppress low-frequency oscillations. The module is compact and can easily be integrated into a test system or with wafer probes.

A power-amplifier module that operates in the frequency range of 145 to 165 GHz has been designed and constructed as a combination of (1) a previously developed monolithic microwave integrated circuit (MMIC) power amplifier and (2) a waveguide module. The amplifier chip was needed for driving a high-electron-mobility- transistor (HEMT) frequency doubler. While it was feasible to connect the amplifier and frequency-doubler chips by use of wire bonds, it was found to be much more convenient to test the amplifier and doubler chips separately. To facilitate separate testing, it was decided to package the amplifier and doubler chips in separate waveguide modules. Figure 1 shows the resulting amplifier module.

Figure 2. Output Power and Gain at 150 GHz were measured as functions of input power. The output power exhibited saturation at 13 dBm.

The amplifier chip was described in “MMIC HEMT Power Amplifier for 140 to 170 GHz” (NPO-30127), NASA Tech Briefs, Vol. 27, No. 11, (November 2003), page 49. To recapitulate: This is a three-stage MMIC power amplifier that utilizes HEMTs as gain elements. The amplifier was originally designed to operate in the frequency range of 140 to 170 GHz. The waveguide module is based on a previously developed lower frequency module, redesigned to support operation in the frequency range of 140 to 220 GHz.

Figure 2 presents results of one of several tests of the amplifier module — measurements of output power and gain as functions of input power at an output frequency of 150 GHz. Such an amplifier module has many applications to test equipment for power sources above 100 GHz.

This work was done by Lorene Samoska and Alejandro Peralta of Caltech for NASA’s Jet Propulsion Laboratory. For further information, access the Technical Support Package (TSP) free on-line at www.techbriefs.com/tsp under the Electronics/Computers category. NPO-40260