Types of Logic Gates     Logic gates are circuits with electronically controlled switches that combine digital signals according to Boolean algebra. In binary math, bits have only two possible values: 0 (off, false) and 1 (on, true). Consequently, there are three basic logic gates from which all other combinatorial logic functions are generated.     Inverters, or NOT gates, have only one input and reverse the logic state. A true input produces a...
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Q & A on Logic Gates

We asked our users for their input on Logic Gates. Here are the results of 92 users familiar with Logic Gates.

Who Took Our Poll? | Design Trends | Applications and Use | Features | Buying Advice

Who Took Our Poll?Top

Design TrendsTop

Q:
What new technologies are influencing logic gate design?
14 answers
Answers:
New Materials High speeds Great performance Small Signal Current
~Marcel Kroppen K, Training as an electronics technician for devices and systems (automated and taxes), Kamp-Lintfort, Germany
Atomic size logic transistor development
~David D'Andrea, Design Engineer, Getzville, NY
FPGA CPLD lower power, higher speed.
~R. A. B, Design Engineer, Hemel Hempstead, UK
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Q:
From your perspective, which companies are creating the most innovative logic gates?
11 answers
Answers:
Altera Xilinx National Semi TI Fairchild Maxim
~R. A. B, Design Engineer, Hemel Hempstead, UK
TI, St Micro, Philips, On Semi
~Component Engineer, Peterborough, Canada
Lattice Semiconductor Corp.
~Gerard R, Engineering Consultant, Fremont, CA
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Applications and UseTop

Q:
What are some of the applications you have used logic gates for?
22 answers
Answers:
Printer I.C., Power management I.C., Disk Drive read-write I.C., Inside thumb drive electronics, Automotive (GM) courtesy light, F14 electronics to control and make early warning counter measure decisions. Agile RADAR aircraft antenna system, control for an electronic automatic RF attenuator. Used in nearly every integrated circuit that I have ever designed.
~Gerard R, Engineering Consultant, Fremont, CA
New product development as well as supporting production with special data traps custom built for the task.
~Engineering, Process/Production, Danville, KY
Implementing multiplexers, demuxs, decoder, encoder, switches and other electronic components.
~Kunal J, Student, Faridabad, India
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Q:
Please share with us any “non-standard” applications that logic gates have been used for.
10 answers
Answers:
Capturing 1 of 16 inputs to an NAND gate resulting in an alarm trigger. Some systems simply monitor events. The actual cause of an alarm may be lost without subsequent re-design.
~Engineering, Process/Production, Danville, KY
Burglar alarm system with: radar detector, SMS message, Call notification of 3 people, automatic door and window lock. All this with NOR and NAND's s.
~Marcel Kroppen K, Training as an electronics technician for devices and systems (automated and taxes), Kamp-Lintfort, Germany
Used precision timer to control power start up sequence measuring the frequency of its own AC power source, then timing the output power delivery from that.
~Steve H, Design Engineer, Portsmouth, England
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Q:
Do you know of any disastrous mistakes that occurred due to the incorrect usage of logic gates?
6 answers
Answers:
Radar simulator design that tried to use cascaded gates to meet delay requirements for data transfer. The product would only work over a very narrow temp range and the company that designed the product was so late to deliver the product it lost the contract.
~David D'Andrea, Design Engineer, Getzville, NY
Mixing families of different voltage ratings. For example, an open collector or open drain line can be driven by one family and input to another and will work intermittently if the voltage ranges overlap, but it's not correct.
~John D, Research & Development, London, Canada
Bought and used logic gates from a manufacturer that has specs for -40 to 85 deg C, in the environment that required -55 to 125 deg C specs.
~Component Engineer, Peterborough, Canada

FeaturesTop

Q:
What would your design or feature "wish list" be for this product?
12 answers
Answers:
Smallest possible size with high reliability, no power dissipation, built in redundancy and high speed that would operate with a supply of (<1.0V).
~Gerard R, Engineering Consultant, Fremont, CA
To work in the same conditions (Speed, Power, Fanin, Fanout...) at very low tensions to medium tensions (0.8V to 15V)
~Serban C, Process Engineer, Cernavoda, Romania
Ability to comply with truth table very quickly after supplies reach minimum specified level.
~Steve H, Design Engineer, Portsmouth, England
Wide temperature range, programmable, low power, Small (compact size), low cost
~Component Engineer, Peterborough, Canada
Built in decoupling. Automatic process to transfer designs from FPGA to ASIC.
~R. A. B, Design Engineer, Hemel Hempstead, UK
Analog multiplexers with low on resistance and fast switch time.
~Ilya Kahn, Project Manager, Sherman Oaks, CA
Compact down internally to ground Direct control of relay without the transistor amplifier small temperature coefficient low thermal unwinding Klung
~Marcel Kroppen K, Training as an electronics technician for devices and systems (automated and taxes), Kamp-Lintfort, Germany
8 input Single or dual gates in chip scale package.
~David D'Andrea, Design Engineer, Getzville, NY
I want to implement RAM with only logic gates.
~Kunal J, Student, Faridabad, India
Drivers for 24VDC control systems.
~Engineering, Process/Production, Danville, KY
Smart modules
~Manufacturing, Richmond, Canada
Fuzzy logic
~Engineering, Consulting, Navi mumbai, India

Q:
Is there any advice you want to share with users to help them avoid common errors in selection or usage of logic gates?
9 answers
Answers:
Watch out for CMOS TTL compatibility problems (they can often be solved with a small: say 47 Ohm resistor). Make sure that the data inputs change on the non active edge of the clock. Make sure you understand the difference between level sensitive and edge sensitive design.
~R. A. B, Design Engineer, Hemel Hempstead, UK
Do not choose through hole non RoHS parts(they are going obsolete). Pay special attention to power dissipation, temperature range of the devices (Similar logic gates from different suppliers may have different temperature and power dissipation specs.)
~Component Engineer, Peterborough, Canada
Pay strict attention to propagation delays and path lengths. Keep things isolated between analog circuitry and digital. Pay attention to how power and ground are routed to minimize glitches and crosstalk.
~Gerard R, Engineering Consultant, Fremont, CA
The fastest gate is not always the best choice for a design. Study the speed and delay requirements for each application and pick the family that meets those requirements.
~David D'Andrea, Design Engineer, Getzville, NY
Be careful when using them in mixed signal applications. They can inject a lot of noise into analog sections.
~John D, Research & Development, London, Canada
First build a truth table and then build up with LOGO Soft (PC program), the circuit.
~Marcel Kroppen K, Training as an electronics technician for devices and systems (automated and taxes), Kamp-Lintfort, Germany
Be careful with: Logic class, Fan in & Fan out; Supply tension, Delay time.
~Serban C, Process Engineer, Cernavoda, Romania
Buy universal gates Nand and Nor. Implement others using them.
~Kunal J, Student, Faridabad, India
Observe all design rules for device family.
~Garnet O, Designer Retired, Surrey, B. C., Canada

Buying AdviceTop

Q:
Do you have any advice for people relative to buying or using logic gates?
8 answers
Answers:
Make sure that the parts you selected are relatively new, not going to be obsolete in the near future. If the life cycle of your product is 10 years plus, ensure that the supply of the parts selected can last at least 10 years plus.
~Component Engineer, Peterborough, Canada
Look at the full specification including voltage rail tolerance, supply rail current and input signal logic thresholds. Work out what logic speed you actually need.
~Steve H, Design Engineer, Portsmouth, England
If the design needs more than a few chips, buy an FPGA dev kit and evaluate.
~R. A. B, Design Engineer, Hemel Hempstead, UK
Pick the lowest voltage family that the design will support.
~David D'Andrea, Design Engineer, Getzville, NY
Supply voltage should be low therefore, buy cmos gates.
~Kunal J, Student, Faridabad, India
In East Europe (I am from Romania) it's a big problem with authenticity of many electronic components. Too many fakes... Just using consecrated providers is possible to have certitude of authenticity. Any way, before purchase, search data sheet of manufacturer (some time and by year of manufacturing of the same manufacturer) especially in case of replacements of originals with other type or other manufacturer.
~Serban C, Process Engineer, Cernavoda, Romania
Learn and use the latest innovations in the state of the art.
~Gerard R, Engineering Consultant, Fremont, CA
By device number
~Garnet O, Designer Retired, Surrey, B. C., Canada


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