Telecoms ♦ news digest
At the Ferdinand-Braun-Institut (FBH), a transferred substrate (TS) technology has been established to optimise high frequency and power performance of InP heterojunction bipolar transistors (HBTs). The 3” wafer-level process enables lithographic access to both the front- and backside of the HBT aligned to each other.
The resulting linear device set-up, shown in Fig. 1, eliminates dominant transistor parasitics and relaxes design trade-offs. The essential step for gaining access to both sides of the epitaxial structure is to completely remove the supporting substrate.
to further enhance the high frequency as well as power performance in the future.
In the study, the researchers designed and produced power amplifiers using TS technology for 90 GHz operation. The S-parameter measurements shown in Fig. 3 agree well with modelling.
Fig. 3: S-parameter measurements of a 90 GHz power amplifier in TS technology
Currently, the innovative transistor set-up is utilised in an ongoing project to integrate InP-based circuits on top of BiCMOS wafers heterogeneously.
Fig. 1: FIB cross-section of a TS-HBT with emitter (e), base (b) and collector (c)
Therefore, a robust adhesive wafer bonding procedure via benzocyclobutene (BCB) has been developed. It yields a homogenous, crack- and void-free composite matrix of transistors transferred on a wafer-level scale.
The optimised device topology enhances the HBT performance dramatically. Transistors with 2 × 0.8 × 5 μm2emitter area, as shown in Fig. 2, feature fT= 376 GHz and fmax= 385 GHz at breakdown voltages BVCEO > 4.5 V.
This research has been described in detail in the paper, “W-Band Amplifier with 8 dB Gain Based on InP- HBT Transferred-Substrate Technology,” by T. Al-Sawaf et al, Proc. German Microwave Conference, Ilmenau, Germany, 12--14 March 2012.
Avago can repurchase up to 15 million shares
The amended share purchase mandate permits the company to repurchase up to 10 percent of its outstanding ordinary shares before its 2013 AGM
Avago Technologies, a supplier of analogue interface components for communications, industrial and consumer applications, has announced that its Board of Directors has authorised the Company to repurchase up to 15 million of its ordinary shares.
This replaces the share repurchase program announced by the company on June 9, 2011, which expired at the Company’s 2012 annual general meeting on April 4, 2012.
Fig. 2: Extrapolated fTand fmax of a TS-HBT
They combine high frequency performance with saturated output power Pout> 14.2 dBm @ 77 GHz and an inherently good matching to 50 Ω. As the device architecture is highly scalable, the researchers at FBH say they may be able
This share repurchase program was adopted pursuant to the share purchase mandate approved by the Avago’s shareholders at its 2012 annual general meeting. The share purchase mandate authorises the repurchase by the Company of up to 10 percent of its outstanding ordinary shares prior to the date of the Company’s 2013 annual general meeting.
Share repurchases, if any, will be made in the open market at April/May 2012
www.compoundsemiconductor.net 107
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