HITEQUEST
technical interview Q & A for high-tech professionals
 
 
Interview Questions
Electronics Hardware
Computer Software
Intel screening questions
Quick Thinking Tests
General questions
Phone screening questions
Submit your Q or A

Resources
Technical articles
Technical discussion
Engineers share info
Resume and interview
How to get a job in Silicon Valley
How much are you worth on market?
Why you may need an agent

Break point
Written Exam
Logic Tests
Professional Test
Tomato company
Cup of coffee
How stock market works
Engineering jokes

About Hitequest
About Hitequest
Home page

 
 
 
 
 
 

 
=Electronics Hardware Questions=

   
   

Q:Design a simple circuit based on combinational logic to double the
output frequency.



 
 

 
  A: ______________ ____ ____ ____ | | _ _ _ _ | | | | | | | | | | | | | | | | _| |____| |____| |__ | | _| |_| |_| |_| |_ | | ------------------------------>| |--------------------> | | |______________| |\ |\ | \ | \ ____| \o_________| \o______ | | / | / | | | / | / | | |/ not |/ not | | | | | \\----. | +----\\ \ | || )--------+ ---+----------------------------------// / //----' XOR

Every signal will appear with a delay on the input 1 comparing to input 2 (see the schematic above) of the XOR element.
The delay is equal to the propagation time of the NOT gates.
Due to the delay the XOR element will generate a pulse on every change of the input signal.

 
 
 

matrixshan:
I believe ( please correct me if I am wrong ) there will be XNOR gate if two NOT gates are being used i.e. effectively XNORing the input and its replica. If XOR gate is used the input signal and its inverted will be XORed.
 
 
 

Someone:
Using two NOT gates to one input of XOR is doing nothing. It is just helpful in generating a delay but not doubling the output frequency.
Instead attaching a buffer to the input of XOR can buy some time and produce a significant delay which can double the output frequency.
 
 
 

Submit your answer here