What is Digital circuits: Definition and 17 Discussions

Digital electronics is a field of electronics involving the study of digital signals and the engineering of devices that use or produce them. This is in contrast to analog electronics and analog signals.
Digital electronic circuits are usually made from large assemblies of logic gates, often packaged in integrated circuits. Complex devices may have simple electronic representations of Boolean logic functions.

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  1. Z

    Write boolean expression describing this circuit

    This problem is from a problem set in the course 6.002 "Circuits and Electronics" of MIT OCW. There are no solutions, unfortunately. By inspection, we can see that the voltage ##V_{OUT}## at terminal OUT in the picture above is high when 1) ##A=0##, because this leaves an open circuit between...
  2. Z

    Why is there a resistor in a MOSFET-based inverter?

    Here is a MOSFET-based inverter combinational gate which we represent with the symbol The MOSFET in the first diagram is itself an abstraction for another circuit (the S model of the MOSFET), which is as follows The MOSFET is a nonlinear circuit but the two sub-circuits above are linear...
  3. Boltzman Oscillation

    Engineering How Do You Determine Node Voltage in a Circuit with Identical BJTs?

    I am given that all the BJTs are the same. First of all, when finding node voltages like Vref should I make the node voltage a voltage source first and then do circuit analysis? If so then I would use KVL but that does not give me Vref = 2Vbe. I do know that Vref = Vb1 = Vb2. What am I doing...
  4. D

    Finding the CMOS transistor width ratio

    Homework Statement Calculate the ration of ##w_p/w_n## if n and p transistors in CMOS inverter necessary for the least delay time ##t_p## if the circuit is used in a chain of circuits. a) What is ##w_p## in that circuit if you're given : b) Calculate the maximum short circuit current if...
  5. D

    Engineering Problem regarding a transistor state in a NAND circuit

    Homework Statement Calculate the output function and draw a graph of output voltage in the function of the input voltage of the following digital circuit: Homework Equations 3. The Attempt at a Solution [/B] By analysis of what happens when inputs A and B are on the logical "1" i have...
  6. D

    Materials for DTL, TTL circuit analysis

    Hi fellow forum-ers :), I have a test in about two weeks where i am going to be given a dtl or ttl circuit which i have to analyse and calculate its function. The professor said that the circuit given to us will always be a useful and existing one meaning he's going to give us some NAND, NOR or...
  7. G

    How to know the duty-cycle of a counter

    Homework Statement Consider the following circuit of a counter with a clock signal of 84 kHz As we can see the counter counts down. Show all the states and transitions of this counter and identify all the states using a binary representation. Calculate the frequency and the duty-cycle of the...
  8. G

    Morse Code Project: Building Circuit for 7 Segment Display

    Homework Statement Hi everyone. I am currently embarking on a Morse Code project which involves building a circuit to display Morse codes, eventually displaying the Morse code with a 7 segment display. I am currently stuck at the first stage as I am not sure of what to do, i.e. what chips to...
  9. G

    Frame Synchronisation via Modified Approach to Bit Insertion

    Homework Statement I am currently embarking on a project which requires me to design a system where I can transmit voice over a distance, by inputting an analog voice signal on one end and then recovering the voice which I input on the transmitting end at the receiving end. The general design...
  10. H

    Digital Circuits and Best Suited MOSFET for 3.3V

    Hello everyone, I wanted to make some digital circuits with discrete CMOS components but I do not know how to read these MOSFET datasheets properly and I have no idea which models are good for these kinds of projects (for a 3.3V as Vdd and with ground). I know the characteristics of MOSFETs...
  11. A

    Good notes on wire models in digital circuits

    Hello everyone. I'm trying to do a homework in digital integrated electronics class and feel like I can finish it only if I had a good set of notes. I have problems like comparing the input capacitance of a Mosfet to a wire of certain length, getting RC time loss in a wire, power...
  12. L

    Digital circuits 2-input multiplexer implemented into an and gate

    How do you implement different gates by using a two-input multiplexer? What are the inputs supposed to be? How do you implement an AND gate, for example? An OR?
  13. B

    How much of analog circuits before digital circuits?

    Hi pf, first time poster, long time lurker. The question that I have is: how much of analog electronic circuits must you know about before digital electronic circuits (I'm talking about the introductory level for both of these subjects). At my school, they offer a 2-part course in analog...
  14. S

    Is Conservation of Energy or Charge Correct in Superconducting Digital Circuits?

    Homework Statement The fundamental concept of charge and energy governs CMOS digital circuits. Your company is excited about the possibility of a truly superconducting three terminal device (i.e. a MOS device with zero on-resistance) to make logic circuits. The argument is that such a device...
  15. L

    Probing high speed digital circuits

    I have a 100MHz bus going from CPU to Memory. The routing length is about 2inches. So there is no termination. When I hook up the bus to a Logic analyzer, how do I know the Logic analyzer probes are not causing any reflection and messing up the bus signals. The length of the probe is about...
  16. L

    Set-up time in digital circuits

    Why should the input in any logic be present before the clock? Is the setup time related to clock rise time?
  17. V

    What is Clock Pulse in Digital Circuits?

    wat is meant by the clock pulse given to the flip flops in digital circuits. Is it just a supply that is given to the ic as long as it is held in on position. How do some chips operate when the clock goes from high to low and not when pulses go from low to high?.