Millimeter-wave AlGaAs-GaAs HBT power operation
The AlGaAs-GaAs HBT has demonstrated good power performance up to 18 GHz. Although f/sub max/ is typically above 100 GHz, the power performance limitation and large signal operation at millimeter wave frequencies have not been studied. Power results from two HBT structures at 35 GHz are analyzed based on numerical simulation. The HBT demonstrated 8.5-dB linear power gain, 30% PAE with 7.8-dB gain and 7.5-V V/sub ce/ bias. The power density reaches 1.25 mW/ mu m/sup 2/. A shorter collector (0.4 mu m) is shown to be better suited for 35-GHz operation as a result of shorter collector transit time and smaller residual collector voltage. Improvement can be achieved by reducing the base and collector resistance, and the collector capacitance.<<ETX>>
Self-Aligned, Emitter-Edge-Passivated AIGaAs/GaAs Heterojunction Bipolar Transistors with Extrapolated Maximum Oscillation Frequency of 350 GHz
Summary form only given. The authors present self-aligned, emitter-edge-passivated AlGaAs/GaAs heterojunction bipolar transistors (HBTs) with extrapolated maximum oscillation frequency of 350 GHz. To the authors' knowledge, this is the highest f/sub max/ ever reported for an HBT. The self-aligned, emitter-edge-passivated dual-liftoff process reported here enhances the device RF performance and DC current gain. The current gain of a typical HBT with 2 emitter fingers each 2 mu m*10 mu m was measured to be more than 20 at current density of 5*10/sup 4/ cm/sup 2/. A record high maximum oscillation frequency of 350 GHz was extrapolated by assuming 6-dB/octave falloff rate from the unilateral gains obtained from the s-parameters measured up to 40 GHz. >
Self-aligned AlGaAs/GaAs heterojunction bipolar transistors for high-speed digital circuits
The AlGaAs/GaAs HBT is one of the most promising of three-terminal high speed devices and has been demonstrated to have potential for digital applications. A frequency divider using CM1 gates operates at speed up to 8.5 GHz2(l) and propagation delay times are as short as 20 psec in NTL gates.(2) In this paper, we describe the successful fabrication of a 1/4 frequency divider which operates up to 13.7 GHz using newly developed self-aligned AlGaAs/GaAs HBTs.