Y.K. Allen

39.5-GHz static frequency divider implemented in AlInAs/GaInAs HBT technology

A static divide-by-4 frequency divider operating at 39.5 GHz with a corresponding gate delay of 12.6 ps was implemented using InP-based HBT technology. The AlInAs/GaInAs HBT devices utilized in the divider incorporated a graded emitter-base (E-B) junction and had a unity gain cutoff frequency, maximum frequency of oscillation, and current gain beta of 130 GHz, 91 GHz, and 39, respectively. The divider was operated with a 3-V power supply and consumed a total power of 425 mW (77 mW per flip-flop). The divider functional yield was over 90%. The operating frequency of this circuit is the highest ever reported for a static divider.<<ETX>>

33-GHz monolithic cascode AlInAs/GaInAs heterojunction bipolar transistor feedback amplifier

Microwave cascode feedback amplifiers with 8.6-dB gain and DC to 33-GHz bandwidth were developed. The amplifiers utilize AlIn-As/GaInAs heterojunction bipolar transistors having f/sub max/=70 GHz and f/sub tau /=90 GHz. Because of the significant collector-base feedback time constant the cascode configuration provides a large improvement in amplifier bandwidth, but a low-impedance bias node must be provided for the common-base transistor. An active bias network was thus used which eliminates the need for on-wafer Si/sub 3/N/sub 4/ bypass capacitors. >

Improved high frequency performance of AlInAs/GaInAs HBTs through use of low temperature GaInAs

GaInAs grown at lower than normal substrate temperatures was used to reduce the amount of beryllium out-diffusion from the heavily doped bases of AlInAs/GaInAs Npn HBTs. A combined 20-nm-thick spacer structure of p-doped and undoped GaInAs grown at 300 degrees C prevented excessive amounts of beryllium from diffusing into the AlInAs emitter. This allowed base beryllium doping concentrations up to 10/sup 20/ cm/sup -3/ to be achieved, thereby reducing base resistance and increasing f/sub max/ to 70 GHz. A fifteen-stage ring oscillator utilizing these HBTs demonstrated a gate delay of 15.8 ps. The reduced outdiffusion was confirmed by secondary ion mass spectrometry (SIMS) elemental profiles in addition to electrical measurements.<<ETX>>

AlInAs/GaInAs HBT IC technology

CML ring-oscillators and static frequency divider circuits implemented with AlInAs/GaInAs heterojunction bipolar transistors (HBTs) lattice matched to InP substrates are demonstrated. A cutoff frequency (f/sub t/) and a maximum frequency of oscillation of 90 GHz and 70 GHz, respectively, have been achieved with a 2*5- mu m/sup 2/ emitter. The ring oscillators demonstrated a 15.8 ps gate delay. The divide-by-two and divide-by-four circuits operated at 22 GHz and 24.8 GHz, respectively.<<ETX>>

High speed dual modulus dividers using AlInAs-GaInAs HBT IC technology

4/5 and 8/9 dual-modulus prescalers are fabricated using AlInAs-GaInAs heterojunction bipolar transistors (HBTs) which operate at clock frequencies up to 9 GHz and which dissipate 700 mW and 900 mW, respectively. The transistor technology results in a cutoff frequency and maximum frequency of oscillation of 90 GHz and 70 GHz, respectively. The 4/5 and 8/9 dividers consists of 106 and 124 transistors, respectively. These are the largest circuits fabricated with HBTs on InP substrates and are among the fastest reported dual-modulus prescalers. The AlInAs-GaInAs HBT technology, circuit design, and measurement results are described.<<ETX>>

Emitter injection and collector current ideality in abrupt heterojunction AlInAs/GaInAs HBTs

Abstract We investigated the electron injection process for high-speed N-p-n AlInAs/GaInAs HBTs by measuring collector and base currents as a function of base-emitter voltage with collector-base voltage equal to zero (Gummel plots) at temperatures from 77 to 300 K. We compared the measured collector current with calculations based on electron injection from emitter to base by tunneling through the conduction band spike and thermionic emission over it, using a modified version of the thermionic-field emission theory developed by Crowell and Rideout. Good agreement was obtained between the experimental collector current ideality factor and tunneling-thermionic emission theory for all temperatures and currents. This is an improvement over drift-diffusion and thermionic emission models, which have been used for HBTs but which do not correctly describe the experimentally observed temperature and current dependence of the ideality of the collector current. The tunneling-thermionic emission model explains the increase in collector current ideality factor that occurs as the transistor is biased at high collector current density ( J C ≧ 10 5 A cm −2 ), which is the regime of operation in which fT is maximized and a low ideality factor is most important. The model also explains the experimentally observed variation of hFE with ln IC. Thus the tunneling-thermionic emission model is a useful aid in the design of the epitaxial structure for high-frequency HBTs.

Performance of AlInAs/GaInAs/InP microwave DHBTs

The authors report the experimental characteristics obtained from AlInAs/GaInAs/InP double heterojunction bipolar transistors (DHBTs) grown by gas source molecular beam epitaxy. They describe the fabrication and measured performance of two AlInAs/GaInAs/InP DHBT structures, one having a relatively thin 390 nm collector and the other having a relatively thick 1200 nm collector. Their performance results are presented within the context of their application to linear ICs and microwave power amplification. The results include the first reported microwave power measurements on this InP-based DHBT structure featuring a continuous wave output power density of 3.3 W/mm at 4 GHz.<<ETX>>

Improved AlInAs/GaInAs HBTs for high-speed circuits

This paper describes the demonstration of CML ring-oscillators and static frequency divider circuits implemented with AlInAs/GalnAs heterojunction bipolar transistors (HBTs) lattice matched to InP substrates. A cutoff frequency (fT) and a maximum frequency of oscillation of 90 GHz and 70 GHz, respectively, have been achieved with a 2x5-?m2 emitter. The ring oscillators demonstrated a 15.8 ps gate delay. The divider circuits were clocked at 24.8 GHz.