Experimental Transistor Breaks 600 Gigahertz

neutron_p writes "The goal of a terahertz transistor for high-speed computing and communications applications could now be within reach. A new type of transistor structure, invented by scientists at the University of Illinois, has broken the 600 gigahertz speed barrier. A new type of transistor - built from indium phosphide and indium gallium arsenide - is designed with a compositionally graded collector, base and emitter to reduce transit time and improve current density. With their pseudomorphic heterojunction bipolar transistor, the researchers have demonstrated a speed of 604 gigahertz - the fastest transistor operation to date."

Comments

Transistor Breaks 600 Gigahertz

[Timesprout]

And is forced to pay for their replacement as well as 100 hours community service.

Re:Transistor Breaks 600 Gigahertz

[sentientbeing]

Terahertz transistors, indium phosphides, indium gallium arsenide, compositionally graded collectors, bases and emitters, reduced transit time and improved current density... And a pseudomorphic heterojunction bipolar transistor with speeds of 604 gigahertz.....

At times like this I like to leave a slashdot page open on articles and walk away from my computer.

Anybody walking past my computer looks at the screen and thinks 'JESUS! How clever is that guy?'

But...

[sulli]

can it be overclocked?

huh

[moonbender]

their pseudomorphic heterojunction bipolar transistor

*blank stare*

What now? It's pronounced nu-cu-lar!

Re:huh

[Anonymous Coward]

pseudomorphic heterojunction bipolar transistor

[sarcasm]
Thank GOD they got this one right! If they would have invented a pseudomorphic homojunction bipolar transistor, the right-wing would have gotten pissed.*
[/sarcasm]

*If you're offended by the above, bugger off.

Bipolar?

[TripMaster Monkey]

From the article:

With their pseudomorphic heterojunction bipolar transistor, the researchers have demonstrated a speed of 604 gigahertz - the fastest transistor operation to date.

Sure...it's fast now, but just wait until it goes into its depressive phase...

Terahertz transistor within reach?

[isd_glory]

Yeah, because after the first 600 GHz, the next 400 GHz are a piece of cake.

Longhorn

[faqmaster]

Just in time for Longhorn!

Not being an EE geek...let me ask a question

[nebaz]

If we assumed that all transistors on a chip (say a P4) were this type of transistor, and could run at 600 GHz, I know there is time required for a signal to cross all of these transistors, etc., and that some chips have a billion transistors on them, how fast could the current chips run with these transistors?

Re:Not being an EE geek...let me ask a question

[RayDude]

I suspect the power requirements for this bi-polar transistor would make it impossible to build something on the scale of a P4.

Bipolar eats power.

I think these transistors, if found to be manufacturable, will probably be used in communications not digital logic.

Raydude

Re:Not being an EE geek...let me ask a question

[mlyle]

It all depends on the wiring delay and how many transistors deep a pipeline stage is.

fMax of a pipeline stage is 1/(switching times+wiring delays) under worst case thermal conditions. The wiring delays will stay about the same unless they're also improved by the new process, which is unlikely.

A 600GHz transistor, with really deep pipelines like the P4, and very good interconnect technology might allow 20-50GHz operation; but there are many other things to contend with (like thermals/dissipation) that can limit speed. Thermals, in turn, depend on the amount of capacitance being switched, which isn't specified here.

Re:Not being an EE geek...let me ask a question

[mothz]

I think these transistors, if found to be manufacturable, will probably be used in communications not digital logic.

Indeed. The transistors used for digital circuits (i.e., computers) are mostly MOSFETs. The chief benefit of MOS transistors is that no current goes into the gate, so power is only used when switching from one state to the other (i.e. from a 1 to a 0).

Bipolar transistors have a base current (albeit small), so they draw power even when responding to a constant signal. However, they're faster and can output a lot more current than MOSFETs, so they do have plenty of other applications.

Re:Not being an EE geek...let me ask a question

[ChrisMaple]

So, if you build the world's fastest transistor, then how do you know how fast it is going since it is obviously well beyond the range of your test equipment?

By heterodyning with (multiplying by) a lower frequency. Look up formula for sin(at) x sin(bt).

Note also that harmonics of a given frequency can be created by passing it through a nonlinearity.

Just like Illinois

[lheal]

They'll be clearly the best engineering team, but will lose in the finals to the more talented squad from MIT.

Another Fast Transistor

[ncg]

More and more we here about these new HBT circuits that are faster than all get out.
The truth is that nothing will replace CMOS anytime soon. The infrastructure is already there, and it is being optimized over and over again and has a huge work force to man it.

I once heard someone ask Intel is they ever plan to switch to HBT for speed. Their response is, and will probably be for a while, that why would they switch technologies after investing $50 billion a year in their CMOS foundries etc.

These advancements may never make it to the point that the average consumer will take notice of them.
And it may be that these academic inventions will never find any market relevance.

Pseudomorphic heterojunction bipolar transistor?

[Wandering Wombat]

Man, that was Final Jeopardy's question last night! Where was this post when I needed it?

Zero gain bandwidth

[wowbagger]

OK, I cannot RTFM right now as it is /.ed, but:

This sounds an awful lot like they are giving the zero-gain bandwidth of the transistor - the frequency at which the transistor does NOT amplfy a signal anymore.

So, at 599GHz the transistor will amplify a little. At 600 GHz the transistor takes as much power to drive the input as it is able to switch at the output. At 601 GHz the transistor takes more power to control than it can switch.

Given a 600 GHz zero-gain bandwidth transistor you ARE NOT going to make a 600 GHz clockspeed processor.

Re:Power usage?

[jridley]

Even worse, over 100 watts of the power is lost to heat!

For all practical purposes, ALL the power is "lost" to heat. Information has SOME thermodynamic value, but it's pretty damn small.

If you have a computer that draws 500 watts of power, you have a 499.99999(etc) watt heater.

How do you measure 604 gigahertz?

[MOBE2001]

the researchers have demonstrated a speed of 604 gigahertz - the fastest transistor operation to date.

How does one measure 604 gigahertz? Just asking.

Re:How do you measure 604 gigahertz?

[John Miles]

Spectrum analyzers could "see" up to 325 GHz directly in the early Eighties. So I'd guess that newer and better waveguide mixers are available now. A Tek 2782 or 2784 analyzer could theoretically display a harmonically-downmixed signal 1.2 THz, although I have no idea how you were supposed to acquire the signal in the first place.

You may not be able to see a single one-picosecond pulse in the time domain, but if you fire off a bunch of them in succession, you can build a picture of the waveform with repetitive sampling techniques. Technology was available in the 1960s to perform repetitive sampling in the 20-picosecond regime, so someone like Tek or Agilent or Picosecond Pulse Labs may have a sampling gate that can do the job.

I would recommend surfing around at PPL's site if you're seriously interested in this stuff. There may also be some photonic tech involved in the measurement; I haven't RTFA yet.

Re:Scope This

[elgatozorbas]

Good question, I asked myself the same one. They did NOT use a string of divider flipflops, as they only just developed the transistor itself, and to do the division the flipflops should be made of a superior technology.

I know special methods exist to predict the f_s from low-frequency measurements. Maybe they measure the amplification at a some 'low' frequencies (GHz range) and extrapolate the gain-bandwidth pruduct from this?

Second answer

[ChrisMaple]

Filters of known frequency response can be made by knowing only their geometry. Pass the signal through several filters of different frequency responses (one at a time) and feed the output of the filter into a resistive material. Measure the temperature of the resistive material. The peak frequency of the filter which warms the resistive material the most is the (approximate) frequency being generated.