Chun-Tung Cheung

A Ka-band grid amplifier module with over 10 Watts output power

We present a Ka-band grid amplifier power module. The module is fully packaged with waveguide input and output flanges. It includes a driver grid amplifier chip for gain, followed by a booster grid amplifier chip for power. With a 50/spl deg/C baseplate temperature, the module has a small signal gain of 12 dB. The single-chip output booster stage delivers over 16 Watts of saturated power. The module delivers over 10 Watts output with a constant 1.6 Watts input over a 550 MHz bandwidth. We also present a large-signal third-order intermodulation and AM/PM conversion measurements, which are consistent with expectations. To our knowledge, this is the highest power ever reported from a monolithic single-chip power amplifier at Ka-band.

A waveguide mode-converter feed for a 5-W, 34-GHz grid amplifier

We have demonstrated a compact waveguide mode converter that excites a combination of TE/sub 10/ and TE/sub 30/ modes for feeding a grid amplifier. The length of the mode converter is only 13 mm. The effective transmitter power (ETP) at 34 GHz is 5 W, with a gain of 5.5 dB and a power-added efficiency (PAE) of 21%. The supply voltage is 3 V, with a bias current of 5.6 A. These results are comparable to those reported earlier for the same grid-amplifier design measured in free space. A spurious oscillation with a broad radiation pattern was observed at 33.6 GHz with an effective isotropic radiated power (EIRP) of 23 mW. This oscillation was suppressed when the grid was operating at high power levels, and disappeared entirely at output powers above 4.5 W.

A single chip two-stage W-band grid amplifier

The first monolithic grid amplifier using a cascade differential-pair amplifier unit cell has been designed and measured. The grid is packaged using reflection architecture with waveguide input and output. The measured gain at 82 GHz is 5.5 dB. The measured output power is 110 mW with 2.5 dB residual gain. The size of the amplifier module is 20 mm/spl times/10 mm/spl times/10 mm.

V-band transmission and reflection grid amplifier packaged in waveguide

We designed and demonstrated two monolithic V-band grid amplifiers packaged in waveguides. We measured a 2 dB small-signal system gain for both transmission and reflection amplifiers. This is the first monolithic grid amplifier packaged and measured in a waveguide in the V-band.

W-band waveguide-packaged InP HEMT reflection grid amplifier

This letter presents a 79-GHz broadband reflection-type grid amplifier using spatial power combining to combine the power of 64 unit cells. Each unit cell uses a two-stage cascade configuration with InP HEMTs arranged as a differential pair. A broadband orthogonal mode transducer (OMT) separates two orthogonally polarized input and output signals over a 75 to 85GHz range. In conjunction with the OMT, a mode converter with quadruple-ridged apertures was designed to enhance the field uniformity over the active grid. Measurements show 5-dB small signal gain at 79GHz and an 800-MHz 3-dB bandwidth. The amplifier generates an output power of 264mW with little evidence of saturation.

Power and spectral regrowth performance of 10-W and 16-W Ka-band power amplifiers with single-chip output stages

By spatially combining the outputs of many solid-state devices on a single chip, grid amplifiers are not only powerful, linear, and efficient, but also are compact, rugged, and robust. We present measured data from a fully-packaged Ka-band module with standard waveguide input and output flanges. With a 50/spl deg/C baseplate temperature, the module can be biased to deliver from 10 to 16 Watts of rated output power in the 30-31 GHz band. The module exhibits very good spectral regrowth performance, and can be operated well into saturation in single-carrier terminals for shared-spectrum multiple-access applications.

A novel dielectric loaded antenna for wireless applications

A new modified gamma-matched dielectric-loaded antenna suitable for terrestrial cellular applications is presented. A lumped-element equivalent circuit model is developed based on the electrical contribution of different elements of the antenna. Measured, simulated and equivalent circuit model predicted return losses are compared to test the validity of our equivalent circuit model.