Transferred-substrate HBT Research Articles

Transferred-substrate HBT integrated circuits

Using substrate transfer processes, we have fabricated heterojunction bipolar transistors with submicron emitter-base and collector-base junctions, minimizing RC parasitics and increasing f max to 500 GHz. The process also provides a microstrip wiring environment on a low- ϵ r dielectric substrate. Demonstrated small-scale ICs in the process include lumped and distribute amplifiers with bandwidths to 85 Hz, 48 GHz static frequency dividers, and 50GHz AGC/limiting amplifiers.

Transferred-substrate HBTs with 254 GHz f τ

The authors report the simultaneous achievement of record current gain cutoff frequency f/sub /spl tau// and high power gain cutoff frequency f/sub max/ in a transferred-substrate HBT. The device parasitics are examined, and inferences made about the relative value of various approaches toward further improvements in f/sub /spl tau// and f/sub max/. Transferred-substrate HBTs with record f/sub /spl tau// of 254 GHz are reported.

48-GHz digital ICs and 85-GHz baseband amplifiers using transferred-substrate HBT's

Using substrate transfer processes, we have fabricated heterojunction bipolar transistors with submicrometer emitter-base and collector-base junctions, minimizing RC parasitics and increasing f/sub max/ to 500 GHz. The process also provides a microstrip wiring environment on a low-/spl epsiv//sub r/ dielectric substrate. First design iterations of emitter-coupled-logic master-slave flip-flops exhibit 48 GHz maximum clock frequency when connected as static frequency dividers. Baseband amplifiers have been demonstrated with bandwidths up to 85 GHz.

48 GHz static frequency dividers in transferred-substrate HBT technology

In addition to an ultrahigh heterojunction bipolar transistor bandwidth, the transferred-substrate process offers the significant advantages of a low parasitic microstrip wiring environment and a low thermal impedance environment. The first digital integrated circuits using this technology, D-flipflops connected as 2:1 static frequency dividers, are reported.

A>400 GHz f/sub max/ transferred-substrate heterojunction bipolar transistor IC technology

We report transferred-substrate AlInAs/GaInAs bipolar transistors. A device having a 0.6 μm×25 μm emitter and a 0.8 μm×29 μm collector exhibited f/sub /spl tau//=134 GHz and f <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">max</sub> >400 GHz. A device with a 0.6 μm×25 μm emitter and a 1.8 μm×29 μm collector exhibited 400 GHz f <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">max</sub> 164 GHz f/sub /spl tau//. The improvement in f <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">max</sub> over previous transferred-substrate HBT's is due to improved base Ohmic contacts, narrower emitter-base and collector-base junction areas, and slightly reduced transit times. The transferred-substrate fabrication process provides electroplated gold thermal vias for transistor heat-sinking and a microstrip wiring environment on a low dielectric constant polymer substrate.

80-GHz distributed amplifiers with transferred-substrate heterojunction bipolar transistors

We report distributed amplifiers with 80 GHz bandwidth and 6.7 dB mid-band gain. These amplifiers were fabricated in the transferred-substrate heterojunction bipolar transistor integrated circuit technology. Transferred-substrate HBT's have very high f/sub max/ (>400 GHz) and have yielded distributed amplifiers with record gain-bandwidth product.