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SSPD_Chapter 7_Part 3_Basic Electrical Properties of MOSFET_continued 8 gives the configuration of BiCMOS inverter and its optimized version.

SSPD_Chapter 7_Part 3_Basic Electric Properties of MOSFET_Continued_8

7.3.15. BiCMOS Inverters.

In the output stage where loads have to be driven, CMOS Logic Gates themselves cannot give adequate current for drivng the loads. In these circuits buffer BJT are added as shown in Figure 7.3.15.1. The inverted logic operation is carried out as shown in Table 7.3.15.1.

Table 7.3.15.1. The Inverted Logic Operation of BiCMOS inverter.

Input Q1 Q2 Q3 Q4 Vout
LOW(GND) off On and Q2 sources current to charge C L to 5V through a low impedance path provided by on BJT Q2 off on HIGH=5-V BE (on)
HIGH(5V) On and Q1 sinks current thereby discharging C L through low impedance path provided by on BJT Q1 off on off LOW = V CE (sat)

The characteristics of BiCMOS Inverter.

i.Logic levels are close to bus voltages;

ii.High input impedance;

iii.Low output impedance;

iv. It has high current drive capability and occupies a relatively small area;

v. It has large Noise Margin.

But this configuration has high standby dissipation under I/P = HIGH condition since Q1 and Q3 provide a low impedance path from Positive Bus to GND bus.

Also this configuration has no path for turning off the BJT when required.This slows the switching operation. Hence we go for improved circuit configuration.

In Figure 7.3.15.2 we have removed the direct dc path from Positive Bus to GND through Q3 and Q1 but when Vin = HIGH, Vout ≠ V CE (sat) which is 0.2V but Vout = V BE (on) = 0.7V. Hence output swing is reduced from full 5V to about 4V.

Also BJTs still donot have a discharge path for their base currents during turn off of the respective BJT. So a third configuration is given in Figure 7.3.15.3.

In the improved version shown in Figure 7.3.15.3. two resistances R1 and R2 are introduced in the discharge paths of the bases of the BJTs , Q1 and Q2. Because of the resistances, the logic levels are improved and hence voltage swing is optimized. The resistances also speed up the switching of the transistors.

Though this is an improved version of BiCMOS Inverter from IC technology point of view it is impractical because passive chip resistances occupy large real estate area and suitable values are difficult to realize. Hence chip resistances are replaced by MOS transistors as shown in Figure 7.3.15.4.

In Figure 7.3.15.4, the function of R1 is fulfilled by Q5 and function of R2 is fulfilled by Q6. The states of different transistors during Inverted Logic Operation are given in Table 7.3.15.2.

Table 7.3.15.2. Inverted Logic Operation of the optimized version ogf BiCMOS.

Vin Q1 Q2 Q3 Q4 Q5 Q6 Vout
HIGH SAT OFF ON OFF ONThis provides the discharge path for the base current of Q2 which was ON previously OFF LOW=V CE (sat)
LOW OFF ON OFF ON OFF ONThis provides the discharge path for the base current of Q1 which was in SAT previously HIGH

This circuit offers enormous advantages where high load current sourcing and sinking are required. Whenever Video Monitors or Speakers are to be driven there we require BiCMOS interface at the output.

Questions & Answers

Is there any normative that regulates the use of silver nanoparticles?
Damian Reply
what king of growth are you checking .?
Renato
What fields keep nano created devices from performing or assimulating ? Magnetic fields ? Are do they assimilate ?
Stoney Reply
why we need to study biomolecules, molecular biology in nanotechnology?
Adin Reply
?
Kyle
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
Adin
why?
Adin
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Kyle
biomolecules are e building blocks of every organics and inorganic materials.
Joe
anyone know any internet site where one can find nanotechnology papers?
Damian Reply
research.net
kanaga
sciencedirect big data base
Ernesto
Introduction about quantum dots in nanotechnology
Praveena Reply
what does nano mean?
Anassong Reply
nano basically means 10^(-9). nanometer is a unit to measure length.
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Damian Reply
absolutely yes
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how to know photocatalytic properties of tio2 nanoparticles...what to do now
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it is a goid question and i want to know the answer as well
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characteristics of micro business
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for teaching engĺish at school how nano technology help us
Anassong
Do somebody tell me a best nano engineering book for beginners?
s. Reply
there is no specific books for beginners but there is book called principle of nanotechnology
NANO
what is fullerene does it is used to make bukky balls
Devang Reply
are you nano engineer ?
s.
fullerene is a bucky ball aka Carbon 60 molecule. It was name by the architect Fuller. He design the geodesic dome. it resembles a soccer ball.
Tarell
what is the actual application of fullerenes nowadays?
Damian
That is a great question Damian. best way to answer that question is to Google it. there are hundreds of applications for buck minister fullerenes, from medical to aerospace. you can also find plenty of research papers that will give you great detail on the potential applications of fullerenes.
Tarell
what is the Synthesis, properties,and applications of carbon nano chemistry
Abhijith Reply
Mostly, they use nano carbon for electronics and for materials to be strengthened.
Virgil
is Bucky paper clear?
CYNTHIA
carbon nanotubes has various application in fuel cells membrane, current research on cancer drug,and in electronics MEMS and NEMS etc
NANO
so some one know about replacing silicon atom with phosphorous in semiconductors device?
s. Reply
Yeah, it is a pain to say the least. You basically have to heat the substarte up to around 1000 degrees celcius then pass phosphene gas over top of it, which is explosive and toxic by the way, under very low pressure.
Harper
Do you know which machine is used to that process?
s.
how to fabricate graphene ink ?
SUYASH Reply
for screen printed electrodes ?
SUYASH
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s. Reply
of graphene you mean?
Ebrahim
or in general
Ebrahim
in general
s.
Graphene has a hexagonal structure
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On having this app for quite a bit time, Haven't realised there's a chat room in it.
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how did you get the value of 2000N.What calculations are needed to arrive at it
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Source:  OpenStax, Solid state physics and devices-the harbinger of third wave of civilization. OpenStax CNX. Sep 15, 2014 Download for free at http://legacy.cnx.org/content/col11170/1.89
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