HBT IC Technology Research Articles

InP HBT IC Technology for Terahertz Frequencies: Fundamental Oscillators Up to 0.57 THz

We report on the development of a 0.25-μm InP HBT IC technology for lower end of the THz frequency band (0.3-3 THz). Transistors demonstrate an extrapolated f <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">max</sub> of >;800 GHz while maintaining a common-emitter breakdown voltage (BVCEO) >;4 V. The transistors have been integrated in a full IC process that includes three-levels of interconnects, and backside processing. The technology has been utilized for key circuit building blocks (amplifiers, oscillators, frequency dividers, PLL, etc), all operating at ≥300 GHz. Next, we report a series of fundamental oscillators operating up to 0.57 THz fabricated in a 0.25-μm InP HBT technology. Oscillator designs are based on a differential series-tuned topology followed by a common-base buffer, in a fixed-frequency or varactor-tuned scheme. For ≥400 GHz designs, a subharmonic down-conversion mixer is integrated to facilitate spectrum measurement. At optimum bias, the measured output power was -6.2, -5.6, and -19.2 dBm, for 310.2-, 412.9-, and 573.1-GHz designs, respectively, with P <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">DC</sub> ≤ 115 mW. Varactor-tuned designs demonstrated 10.6-12.3 GHz of tuning bandwidth up to 300 GHz.

Sub-Nanosecond Greater-Than-10-V Compact Tunable Pulse Generator for Low-Duty-Cycle High-Peak-Power Ultra-Wideband Applications

An ultra-wideband pulse generator was designed and fabricated in GaAs HBT IC technology. The generator includes delay and differential circuits to convert a TTL input into a Gaussian pulse signal as well as a Class-C amplifier to boost the pulse amplitude while compressing the pulse width. By adjusting the collector bias of the Class-C amplifier, the pulse amplitude can be varied linearly between 3.5 V and 11.5 V while maintaining the pulse width at 0.3 ± 0.1 nanosecond. Alternatively, by adjusting the base bias of the Class-C amplifier, the pulse width can be varied linearly between 0.25 ns and 0.65 ns while maintaining the pulse amplitude at 10 ± 1 V. Finally, the amplified Gaussian signal can be shaped into a monocycle signal by anL-Cderivative circuit. The present pulse generator compares favorably with pulse generators fabricated in CMOS ICs, step-recovery diodes, or other discrete devices.

110+ GHz Transimpedance Amplifier in InP-HBT Technology for 100 Gbit Ethernet

A 50 dB-Ω transimpedance amplifier (TIA) with a bandwidth greater than 110 GHz has been demonstrated using InP HBT technology. The wide-band amplifier with a cutoff frequency > 110 GHz was designed and fabricated in HRL Laboratories' G4 0.25 μm InP HBT IC technology. The amplifier operates at -4.0 V with a current draw of 76 mA for a power consumption of 304 mW. The basic Cherry-Hooper gain cell is used with a single-ended input and a differential output buffer stage.

IF-sampling fourth-order bandpass /spl Delta//spl Sigma/ modulator for digital receiver applications

Bandpass modulators sampling at high IFs (/spl sim/200 MHz) allow direct sampling of an IF signal, reducing analog hardware, and make it easier to realize completely software-programmable receivers. This paper presents the circuit design of and test results from a continuous-time tunable IF-sampling fourth-order bandpass /spl Delta//spl Sigma/ modulator implemented in InP HBT IC technology for use in a multimode digital receiver application. The bandpass /spl Delta//spl Sigma/ modulator is fabricated in AlInAs-GaInAs heterojunction bipolar technology with a peak unity current gain cutoff frequency (f/sub T/) of 130 GHz and a maximum frequency of oscillation (f/sub MAX/) of 130 GHz. The fourth-order bandpass /spl Delta//spl Sigma/ modulator consists of two bandpass resonators that can be tuned to optimize both wide-band and narrow-band operation. The IF is tunable from 140 to 210 MHz in this /spl Delta//spl Sigma/ modulator for use in multiple platform applications. Operating from /spl plusmn/5-V power supplies, the fabricated fourth-order /spl Delta//spl Sigma/ modulator sampling at 4 GSPS demonstrates stable behavior and achieves a signal-to-(noise + distortion) ratio (SNDR) of 78 dB at 1 MHz BW and 50 dB at 60 MHz BW. The average SNDR performance measured on over 250 parts is 72.5 dB at 1 MHz BW and 47.7 dB at 60 MHz BW.

A low-power 72.8-GHz static frequency divider in AlInAs/InGaAs HBT technology

We report a 72.8-GHz fully static frequency divider in AlInAs/InGaAs HBT IC technology. The CML divider operates with a 350-mV logic swing at less than 0-dBm input power up to a maximum clock rate of 63 GHz and requires 8.6 dBm of input power at the maximum clock rate of 72.8 GHz. Power dissipation per flip-flop is 55 mW with a 3.1-V power supply. To our knowledge, this is the highest frequency of operation for a static divider in any technology. The power-delay product of 94 fJ/gate is the lowest power-delay product for a circuit operating above 50 GHz in any technology. A low-power divider on the same substrate operates at 36 GHz with 6.9 mW of dissipated power per flip-flop with a 3.1-V supply. The power delay of 24 fJ/gate is, to our knowledge, the lowest power-delay product for a static divider operating above 30 GHz in any technology. We briefly review the requirements for benchmarking a logic family and examine the historical trend of maximum clock rate in high-speed circuit technology.

New submicron HBT IC technology demonstrates ultra-fast, low-power integrated circuits

A new submicron HBT-based integrated circuit technology has been developed to fabricate transistors as small as 0.2 /spl mu/m/sup 2/ emitter geometry. Using this novel process approach we have been able to reduce our minimum device geometry by a factor of more than ten, and reduce the metallization pitch by a factor of two compared to our baseline process. At the same time, the device RF performance improved by a factor of two. Submicron heterojunction bipolar transistors (HBT's) fabricated with this process exhibited f/sub T/ and f/sub max/ values greater than 165 and 140 GHz, respectively, and dc current gain of over 50. We have also demonstrated several circuits using submicron HBT's in this new IC technology. In particular, a latching comparator circuit which is a key building block of analog-to-digital converters, performed at 40 GHz. It exhibited three times the speed, one-third the dc power, and one-third the chip size of a similar circuit in our baseline process. A single-chip, PLL-based clock and data recovery circuit was fully functional at 4 GHz with a power supply voltage of 2.5 V. It consumed a total dc power of 50 mW, including input and output buffers.

Reliability of InP-based HBT IC technology for high-speed, low-power applications

We report on the reliability of an InP-based AlInAs/GaInAs heterojunction bipolar transistor technology which has applications in very high-speed and low power integrated circuits. We have performed extensive accelerated lifetest experiments under different dc bias conditions and different ambient temperatures. For high-performance devices we predict meantime-to-failures in excess of 10/sup 7/ hours at 125/spl deg/C junction temperatures. We have also investigated the effects of hydrogen on HBT device characteristics which is particularly important for integrated circuits in hermetically sealed packages. We show that the transistor performance is not sensitive to a 4% hydrogen ambient. For integrated circuits requiring precision thin-film resistors we performed lifetest experiments on tantalum-nitride resistors used in our IC process. We show that these thin-film resistors are very stable and exhibit mean-time-to-failures exceeding that of discrete transistors.

GaAs HBT 0.75-5 GHz multifunctional microwave-analog variable gain amplifier

We report on a GaAs HBT 3-stage variable gain amplifier operating over a 0.75-5 GHz frequency band. The amplifier is broken up into a single-ended HBT LNA pre-amplifier, an analog current steering differential cascode cell for variable gain control, and a differential amplifier output stage. The broadband pre-amplifier is required to reduce the inherently noisy differential cascode stage, and an output differential amplifier is used to provide output drive capability and differential to single-ended conversion. The VGA has a maximum gain of 23.8 dB gain, an IP3>18 dBm, and a noise figure of 6.5 dB. The variable gain control range is >35 dB. This chip demonstrates the versatility of HBT IC technology which can integrate digital, analog, and microwave circuit functions to achieve high performance in a single monolithic chip. >

First demonstration of 60 GHz- f T , GaInP/GaAs HBT IC technology with 28 ps ECL gate delay

A fully integrated GaInP/GaAs HBT IC process with Schottky diodes, nichrome resistors, MIM capacitors and air-bridge inductors is presented. The HBTs have an fT and fmax of 60 and 45 GHz, respectively. Unloaded ECL gate delays of 28 ps are obtained from ring oscillator measurements. A divide-by-eight prescaler circuit clocks at 12.5 GHz.

10-Gbit/s optical receiver using ICs with low-capacitance HBT technology

Abstract A 10-Gbit/s optical receiver is developed using low-capacitance HBT IC technology. The HBT allows a cutoff frequency of 45 GHz and a maximum oscillation frequency of 70 GHz. The receiver contains an automatic gain-control amplifier IC with a gain of 16 dB, a bandwidth of 10.7 GHz, and a decision-circuit IC with an ambiguity of 66 mVp-p at a data rate of 10 Gbit/s. The sensitivity of this receiver is −26.5 dBm at a bit error rate of 10−9. Transmission over a 140-km fiber was achieved successfully.

A 45GHz AlGaAs/GaAs HBT IC Technology without Ion-Implantation

A 45GHz HBT IC technology with 1.4THz Schottky diodes is described. The process is mesa isolated and implant-free. The process integrates NiCr resistors, MIM capacitors and air-bridge inductors. A divide-by-eight prescaler shows good performance up to 13.5GHz. A pulser circuit using the Schottky diodes produced a voltage pulse with 10.35ps rise time.