<< Chapter < Page Chapter >> Page >
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

where we get a research paper on Nano chemistry....?
Maira Reply
what are the products of Nano chemistry?
Maira Reply
There are lots of products of nano chemistry... Like nano coatings.....carbon fiber.. And lots of others..
learn
Even nanotechnology is pretty much all about chemistry... Its the chemistry on quantum or atomic level
learn
Google
da
no nanotechnology is also a part of physics and maths it requires angle formulas and some pressure regarding concepts
Bhagvanji
hey
Giriraj
Preparation and Applications of Nanomaterial for Drug Delivery
Hafiz Reply
revolt
da
Application of nanotechnology in medicine
what is variations in raman spectra for nanomaterials
Jyoti Reply
I only see partial conversation and what's the question here!
Crow Reply
what about nanotechnology for water purification
RAW Reply
please someone correct me if I'm wrong but I think one can use nanoparticles, specially silver nanoparticles for water treatment.
Damian
yes that's correct
Professor
I think
Professor
Nasa has use it in the 60's, copper as water purification in the moon travel.
Alexandre
nanocopper obvius
Alexandre
what is the stm
Brian Reply
is there industrial application of fullrenes. What is the method to prepare fullrene on large scale.?
Rafiq
industrial application...? mmm I think on the medical side as drug carrier, but you should go deeper on your research, I may be wrong
Damian
How we are making nano material?
LITNING Reply
what is a peer
LITNING Reply
What is meant by 'nano scale'?
LITNING Reply
What is STMs full form?
LITNING
scanning tunneling microscope
Sahil
how nano science is used for hydrophobicity
Santosh
Do u think that Graphene and Fullrene fiber can be used to make Air Plane body structure the lightest and strongest. Rafiq
Rafiq
what is differents between GO and RGO?
Mahi
what is simplest way to understand the applications of nano robots used to detect the cancer affected cell of human body.? How this robot is carried to required site of body cell.? what will be the carrier material and how can be detected that correct delivery of drug is done Rafiq
Rafiq
if virus is killing to make ARTIFICIAL DNA OF GRAPHENE FOR KILLED THE VIRUS .THIS IS OUR ASSUMPTION
Anam
analytical skills graphene is prepared to kill any type viruses .
Anam
Any one who tell me about Preparation and application of Nanomaterial for drug Delivery
Hafiz
what is Nano technology ?
Bob Reply
write examples of Nano molecule?
Bob
The nanotechnology is as new science, to scale nanometric
brayan
nanotechnology is the study, desing, synthesis, manipulation and application of materials and functional systems through control of matter at nanoscale
Damian
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
what school?
Kyle
biomolecules are e building blocks of every organics and inorganic materials.
Joe
Got questions? Join the online conversation and get instant answers!
Jobilize.com Reply

Get the best Algebra and trigonometry course in your pocket!





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
Google Play and the Google Play logo are trademarks of Google Inc.

Notification Switch

Would you like to follow the 'Solid state physics and devices-the harbinger of third wave of civilization' conversation and receive update notifications?

Ask