C. Bergamaschi

A laterally etched collector InP/InGaAs(P) DHBT process for high speed power applications

We present a selective laterally wet etched collector InP/InGaAs/InGaAsP double heterojunction bipolar transistor (DHBT) with a quaternary step graded base collector structure. This device shows a DC current gain of /spl beta/=70 over a large collector current range, a breakdown voltage of BV/sub CEO/=10.5 V, and a maximal collector emitter voltage of more than 5.5 V at 10/sup 5/ A/cm/sup 2/ collector current density. A transit frequency of f/sub T/=115 GHz and a maximum oscillation frequency of f/sub max/=170 GHz were achieved.

Gain limitations of scaled InP/InGaAs heterojunction bipolar transistors

We investigate a current gain degradation mechanism in self-aligned InP/InGaAs heterojunction bipolar transistors. We show that surface level pinning at the emitter sidewall gives rise to a peripheral emitter injection current into the base which increases the base current due to electrons recombining at the base contacts. The surface charge at the extrinsic base surface causes the formation of a conducting channel which further enhances the electron flow from the emitter to the base contacts. Two-dimensional numerical simulations of the emitter region combined with Monte-Carlo simulations of the injection process at the abrupt base-emitter heterojunction are in good agreement with the measurements. This effect will be especially severe for submicron emitter widths where the emitter perimeter to emitter area ratio is large.

A 53 GHz monolithically integrated InP/InGaAs PIN/HBT receiver OEIC with an electrical bandwidth of 63 GHz

We report on the characterization of a monolithically integrated InP/InGaAs PIN/HBT-Photoreceiver for a wavelength of /spl lambda/=1.55 /spl mu/m. The preamplifier achieves a transimpedance gain of 44.3 dB/spl Omega/ (164 /spl Omega/) and a bandwidth of 63 GHz, whereas the optical/electrical -3 dB-bandwidth of the entire receiver is 53 GHz. A pulse width of 10.5 ps was measured for the system consisting of receiver, on-wafer probe, bias-tee and sampling-scope. Finally we present eye pattern measurements at 40 Gb/s with a RZ coded optical input signal.

High speed, monolithically integrated pin-HEMT photoreceiver fabricated on InP with a tunable bandwidth up to 22 GHz using a novel circuit design

High speed monolithically integrated photoreceivers were fabricated showing flat photo response and a state of the art bandwidth of 18 GHz, which should be sufficient for data transmission systems well beyond 20 Gbit/s. The circuitry consists of a high input impedance front-end design followed by an equalizing second stage to compensate the input capacitance. A state of the art input noise current of 12 pA//spl radic/Hz within the bandwidth was obtained. The bandwidth of the photoreceiver can be tuned with the bias voltages. For a 3 dB peak at 15 GHz a total bandwidth of 22 GHz was obtained.

23 GHz monolithically integrated InP/InGaAs PIN/HBT-receiver with 12 THz/spl Omega/ gain-bandwidth product

We report on the design, fabrication and characterization of a monolithically integrated InP/InGaAs PIN/HBT-photoreceiver for a wavelength of /spl lambda/=1.55 /spl mu/m. The three-stage-amplifier achieves a transimpedance of 54.5 dB/spl Omega/ (530 /spl Omega/) and the optical/electrical -3dB-bandwidth of the entire receiver is 23 GHz. This corresponds to a transimpedance-bandwidth product of 12 THz/spl Omega/, which is one of the highest values published to date.

50 GHz monolithically integrated InP/InGaAs PIN/HBT-receiver

We have designed and fabricated a monolithically integrated InP/InGaAs PIN/HBT-photoreceiver for a wavelength of /spl lambda/=1.55 /spl mu/m. The transimpedance amplifier achieves a gain of 44.6 dB/spl Omega/ 170 /spl Omega/, and the optical/electrical -3 dB-bandwidth of the entire receiver is 50 GHz, the largest bandwidth reported for any long-wavelength receiver OEIC.

Minimization of the noise measure of InP/InGaAs HBTs

A complete noise characterization as a function of emitter-geometry, temperature, bias-point and frequency (2-26 GHz) of InP/InGaAs HBTs was carried out. Measurements and simulations have shown that there is an optimum emitter geometry and bias point for achieving a minimum noise measure. The noise measure is very important figure of merit in broadband amplifier design because not only the noise but also the gain of the device is taken into account. The measured noise characteristics are validated by an equivalent circuit model with associated noise sources at different device temperatures.

18 GHz high gain monolithically integrated InP/InGaAs PIN/HBT-Receiver

We report on the design, fabrication and characterization of a monolithically integrated InP/InGaAs PIN/HBT-Photoreceiver for a wavelength of . Base and collector layers of the HBT have been used to implement the photodiodes. The three-stage-amplifi erachieves a transimpedance of ( ) and the optical/electrical -bandwidth of the entire receiver is . This corresponds to a transimpedancebandwidth product of , which is one of the highest values published to date.

Noise model of InP-InGaAs SHBTs for RF circuit design

A scalable small-signal and noise model of InP-InGaAs single heterojunction bipolar transistors was developed. Effects which become important at higher frequencies such as the correlation between base and collector current noise and frequency-dependent base current noise are taken into account. We will show that these effects are significant at frequencies higher than 40 GHz and can no longer be neglected. Our model also includes the effects of the different emission coefficients of the base and collector currents. Using this improved model, a direct-coupled, lumped broad-band amplifier was designed. We completely characterized the fabricated circuit with respect to small-signal, noise, and linearity behavior. A -3-dB bandwidth of 50 GHz with a dc gain of 9.8 dB and a gain-peaking of only 1.2 dB were achieved. All these values agree very well with the simulation results. The noise figure is 7.5 dB over a large frequency range. In the frequency range from 2 to 50 GHz, the third-order intercept point IP/sub 3/ and 1-dB compression point at the output have values from 17 to 10 dBm and 3 to 0 dBm, respectively.

Design and characterization of a 50 GHz InP/InGaAs HBT amplifier

The design and a complete small-signal, noise and linearity characterization ion of a direct-coupled, lumped broadband amplifier utilizing InP/InGaAs single heterojunction bipolar transistors (SHBT) was carried out. A -3 dB-bandwidth of 50 GHz with a DC-gain of 9.8 dB and a gain-peaking of only 1.2 dB were achieved. The noise figure is 7.5 dB over a large frequency range. In the frequency range from 2 to 50 GHz, the third-order intercept point and 1 dB compression point at the output have values from 17 to 10 dBm and 3 to 0 dBm, respectively.