we say CMOS is more reliable than BJT,why?

[hsiangleung]

CMOS continues its dominance over BJT for many reasons. One of them I found is CMOS is more reliable. What does that mean? I interpret it as CMOS has less leakage current while BJT requires base current. is it right? how do we understand cmos more reliable?

 

[snishanth512]

We can drive the CMOS circuit with minimum current.

BJT is a current controlled device.

CMOS is voltage controlled device.

So, to perform simple logical operation with BJT it consumes more current when compared to CMOS.

And we use battery as power source in portable devices.

In the case of BJT, the battery will drain soon (than CMOS).

 

[hsiangleung]

Thanks for your attention. As you mentioned, CMOS is power efficient for logical operation. That is true. but does reliability here mean power efficiency?

We can drive the CMOS circuit with minimum current.

BJT is a current controlled device.

CMOS is voltage controlled device.

So, to perform simple logical operation with BJT it consumes more current when compared to CMOS.

And we use battery as power source in portable devices.

In the case of BJT, the battery will drain soon (than CMOS).

 

[godfreyl]

I don't see why CMOS should be considered more reliable than BJT for small signal or digital ICs.

MOSFETS may be considered more rugged than BJT power transistors, if only because they don't suffer from secondary breakdown.

 

[dick_freebird]

"We", Kemo Sabe?

I'd say well more than half of the high reliability ICs I've
designed, have been on bipolar technologies.

You can break either one, but MOSFETs have classes of
reliability problems (oxide wearout, hot carrier, NBTI) in
-normal- operation that BJTs simply don't. Vertical BJTs,
anyway - laterals are exposed to a lot of low quality
oxide over the base. And yet outside of some abnormal
environments, even these seem to do fine on a lot of
parts that have been on the job for many decades.

To paraphrase Bob Marley, "no thin ox, no cry".