A monolithic 35 GHz HBT quasi-optical grid oscillator

The authors report on the fabrication and testing of a monolithic 35-GHz grid oscillator. The frequency of operation was 34.6-GHz at 13 dBm estimated ERP (equivalent radiated power). The device consists of an array of 6 by 6 HBT (heterojunction bipolar transistor) unit cells. The chip dimensions were 6 mm by 7 mm. Oscillators of this kind utilize the free-space propagation characteristics of electromagnetic beams to synchronize the operation of many spatially separated devices. Grid devices use optical techniques to provide electrical functions such as feedback and power combining. The frequency of operation is determined by the dimension of the unit cell and by the distance from the reflecting (feedback) back mirror. Higher frequencies require smaller unit cells, thus opening the possibility of very compact high-power millimeter-wave sources.<>