Abstract: The present invention relates to a heterojunction bipolar transistor structure having a device mesa 401 with a collector region 402, a base region 403 and an emitter region 404. An emitter metal layer 405 is connected to a ballast resistor 406 which in turn is connected to an emitter bump 407 by way of the air bridge 408. The thermal bump 409 is connected to the emitter metallization by way of a layer of heat dissipation material 410, preferably silicon nitride. The present structure enables dissipation of heat at the emitter contact as well as a ballast resistor connected to the emitter by way of metallization 405. This arrangement enables the dissipation of joule heat to avoid higher temperature of operation which results increased current at the collector which increases the temperature thereby further increasing the current, as well as provides a ballast resistor to reduce the collector current back to an acceptable value to avoid thermal runaway.

Abstract: A silicon bipolar junction transistor in integrated form is disclosed having a ballast resistance integrated onto a silicon chip. This resistance is for the purpose of thermal stability. In addition, a bypass capacitance circuit is placed in parallel with the ballast resistance again in integrated form. The silicon BJT is flip-chip mounted on a heterolithic microwave integrated circuit glass substrate having the integrated bypass capacitor circuit fabricated directly thereon. This bypass capacitor circuit is electrically in contact with the emitter fingers of the bipolar junction transistor.

Abstract: A PIN detector for use in the communications industry having increased linearity and increased maximum optical power detection levels without distortion is disclosed herein. To this end, a PIN structure having a high carrier mobility quaternary material cap layer and a ternary photosensitive layer is disclosed that overcomes the limitations of low mobility devices as described above. The quaternary materials have much greater carrier mobility than InP material and thereby a much shorter carrier transit time across these layers. This reduced carrier transit time effect results in a much more linear response and accordingly greatly reduced intermodulation distortion.

Abstract: A short distance ultrasonic distance meter is disclosed with provisions to reduce the ill-effects of ringing when measurements are of obstacles closer than about ten inches. In one embodiment an opposite phase ultrasonic wave is introduced by a circuit (245) and in another embodiment a strain sensor (232) introduces negative feedback to effect cancellation of ringing (147). Finally, in a third embodiment, both the negative feedback and opposite phase methods are employed for optimal results.