if the input clock frequency of the 2 bit up counter is 12 khz, then the output clock frequency will be
Mohammed
Guys, does anyone know the answer?
get if the input clock frequency of the 2 bit up counter is 12 khz, then the output clock frequency will be from screen.
Digital Electronics
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Discussion :: Digital Electronics - Section 2 (Q.No.40)
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40.
In a mod-12 counter the input clock frequency is 10 kHz. The output frequency is
[A]. 0.833 kHz [B]. 1.0 kHz [C]. 0.91 kHz [D]. 0.77 kHz Answer: Option A Explanation:
Mod-12 counter is divide by 12 counter. Output frequency = = 0.833 kHz.
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Sri said: (Mar 31, 2018)
Mod 12 has 4 FF then output frequency should be 1.25 KHZ. Please anyone explain the answer.
Piyush Satasiya said: (Aug 10, 2018)
Yes, agree it is 1.25 kHz.
Shiva said: (May 3, 2019)
For a binary counter or M mod counter, the output frequency is f/2^n irrespective of the synchronous and asynchronous counter where f is the input frequency n is a number of flip-flops (only if duty cycle =50%).
Sourav said: (Sep 14, 2019)
It's correct .833khz.
Since mod-12 counter is a shortened modulus counter it does not utilizes all the possible states. Therefore it's a divide by N counter.
Muthu said: (May 29, 2020)
Thanks all for explaining.
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Frequency Division using Divide
Electronics Tutorial about Frequency Division using Divide-by-2 Toggle Flip-flops to produce an Asynchronous Counter
Frequency Division
Frequency Division uses divide-by-2 toggle flip-flops as binary counters to reduce the frequency of the input clock signal
In the Sequential Logic tutorials we saw how D-type Flip-Flop´s work and how they can be connected together to form a Data Latch. Another useful feature of the D-type Flip-Flop is as a binary divider, for Frequency Division or as a “divide-by-2” counter.
Here the inverted output terminal Q (NOT-Q) is connected directly back to the Data input terminal D giving the device “feedback” as shown below.
frequency Division Divide-by-2 Counter
It can be seen from the frequency waveforms above, that by “feeding back” the output from Q to the input terminal D, the output pulses at Q have a frequency that are exactly one half ( ƒ ÷ 2 ) that of the input clock frequency. In other words the circuit produces Frequency Division as it now divides the input frequency by a factor of two (an octave).
This then produces a type of counter called a “ripple counter” and in ripple counters, the clock pulse triggers the first flip-flop whose output triggers the second flip-flop, which in turn triggers the third flip-flop and so on through the chain producing a rippling effect (hence their name) of the timing signal as it passes through the chain.
The Toggle Flip-Flop
Another type of digital device that can be used for frequency division is the T-type or Toggle flip-flop. With a slight modification to a standard JK flip-flop, we can construct a new type of flip-flop called a Toggle flip-flop.
Toggle flip flops can be made from D-type flip-flops as shown above, or from standard JK flip-flops such as the 74LS73. The result is a device with only two inputs, the “Toggle” input itself and the negative controlling “Clock” input as shown.
74LS73 Toggle Flip Flop
A “Toggle flip-flop” gets its name from the fact that the flip-flop has the ability to toggle or switch between its two different states, the “toggle state” and the “memory state”. Since there are only two states, a T-type flip-flop is ideal for use in frequency division and binary counter design.
Binary ripple counters can be built using “Toggle” or “T-type flip-flops” by connecting the output of one to the clock input of the next. Toggle flip-flops are ideal for building ripple counters as it toggles from one state to the next, (HIGH to LOW or LOW to HIGH) at every clock cycle so simple frequency divider and ripple counter circuits can easily be constructed using standard T-type flip-flop circuits.
If we connect together in series, two T-type flip-flops the initial input frequency will be “divided-by-two” by the first flip-flop ( ƒ ÷ 2 ) and then “divided-by-two” again by the second flip-flop ( ƒ ÷ 2 ) ÷ 2, giving an output frequency which has effectively been divided four times, then its output frequency becomes one quarter value (25%) of the original clock frequency, ( ƒ ÷ 4 ).
Each time we add another toggle or “T-type” flip-flop to the chain, the output clock frequency is halved or divided-by-2 again and so on, giving an output frequency of 2n where “n” is the number of flip-flops used in the sequence.
Then the Toggle or T-type flip-flop is an edge triggered divide-by-2 device based upon the standard JK-type flip flop and which is triggered on the rising edge of the clock signal. The result is that each bit moves right by one flip-flop. All the flip-flops can be asynchronously reset and can be triggered to switch on either the leading or trailing edge of the input clock signal making it ideal for Frequency Division.
This type of counter circuit used for frequency division is commonly known as an Asynchronous 3-bit Binary Counter as the output on QA to QC, which is 3 bits wide, is a binary count from 0 to 7 for each clock pulse.
In an asynchronous counter, the clock is applied only to the first stage with the output of one flip-flop stage providing the clocking signal for the next flip-flop stage and subsequent stages derive the clock from the previous stage with the clock pulse being halved by each stage.
This arrangement is commonly known as Asynchronous as each clocking event occurs independently as all the bits in the counter do not all change at the same time. As the counter counts sequentially in an upwards direction from 0 to 7. This type of counter is also known as an “up” or “forward” counter (CTU) or a “3-bit Asynchronous Up Counter”. The three-bit asynchronous counter shown is typical and uses flip-flops in the toggle mode. Asynchronous “Down” counters (CTD) are also available.
Truth Table for a 3-bit Asynchronous Up Counter
Clock Cycle Output Bit Pattern
QC QB QA 0 0 0 0 1 0 0 1 2 0 1 0 3 0 1 1 4 1 0 0 5 1 0 1 6 1 1 0 7 1 1 1
Therefore we can see that the output from the D-type flip-flop is at half the frequency of the input, in other words it counts in 2’s. By cascading together more D-type or Toggle Flip-Flops, we can produce a divide-by-2, divide-by-4, divide-by-8, etc. circuit which will divide the input clock frequency by 2, 4 or 8 times, in fact any value to the power-of-2 we want making a binary counter circuit.
स्रोत : www.electronics-tutorials.ws
[Solved] In the circuit shown, the clock frequency, i.e., the frequen
let Initial states be Q1 = Q2 = 0 \({D_1} = \begin{array}{*{20}{c}} {\overline {{Q_1}} }&{\overline {{Q_2}} } \end{array}\) D2 = Q1 Hence after 3 clock
Home Digital Electronics Sequential Circuits Synchronous Counters Modulus of a Counter
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In the circuit shown, the clock frequency, i.e., the frequency of the Clk signal, is 12 kHz.The frequency of the signal at Q2 is ____ kHz.
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let Initial states be Q1 = Q2 = 0
D1=Q1―Q2― D2 = Q1
Hence after 3 clock pulses, the output repeats
It is mod – 3 counter
out frequency =123=4 kHz.
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Guys, does anyone know the answer?