Toshiba breaks output record for X-band FET
Toshiba claims that it has broken the output power record for a GaN field effect transistor (FET) operating in the X-band (8 GHz-12 GHz), a frequency range used for radar and satellite communications.
The latest chip, which is 3.4 mm by 0.53 mm in size, delivers 81.3 W at 9.5 GHz and operates at a power density that is six times greater than that of a GaAs FET.
The record output results from optimization of the composition and thickness of the epilayers, the gate length and the distance between the source and drain electrodes.
A unique gate electrode structure and overcoat process suppressed the gate leakage current to one-thirtieth of that of FETs built using today's conventional technology, says Toshiba, and this improved high-voltage operation.
The chip's power dissipation was improved by mounting the FET in a 21.5 mm x 12.9 mm package.
Toshiba is now releasing samples based on this technology with output powers of typically 50 W, and plans to begin mass production within six months.
The chips will be manufactured using stepper technology, because this better-suited to X-band FETs, which feature a gate length of less than 0.5 µm, than a lithographic process.
The company is also developing Ku-band FETs (12 GHz-18 GHz) that will draw on the technology that features in the X-band transitors.
