Circuits
In a pulse generator circuit featuring a 2-input NAND gate and a series of inverters causing a propagation delay, how would the output correspond to the input timing diagram?
Design Verification Engineer
Apple
Akamai
Rolls-Royce Holdings
Synopsys
ASUS
Fujikura
Answers
Anonymous
10 months ago
In a pulse generator circuit using a 2-input NAND gate and inverters with propagation delays, the output pulse timing can be understood through the following steps:
Understanding NAND Gate Behavior:
A 2-input NAND gate outputs a LOW (0) when both inputs are HIGH (1); otherwise, it outputs HIGH (1).
Input Timing Diagram:
Let's denote the two inputs to the NAND gate as
𝐴
A and
𝐵
B.
Assume
𝐴
A and
𝐵
B have some input pulse timings (HIGH and LOW transitions) over time.
Propagation Delay of Inverters:
Inverters introduce a small delay in propagating the input signal to their output. This delay could be denoted as
𝜏
τ (tau).
Output Timing Diagram:
Initially, when both inputs
𝐴
A and
𝐵
B are LOW (0), the NAND gate output will be HIGH (1).
When one of the inputs (say
𝐴
A) transitions from LOW to HIGH (0 to 1):
Due to the propagation delay
𝜏
τ, the output of the corresponding inverter connected to
𝐴
A will change with a delay.
This delay causes a brief moment where the NAND gate sees one input (from
𝐵
B) as HIGH and the other (from
𝐴
A) as still LOW (since
𝐴
A is transitioning).
Therefore, the NAND gate output will momentarily go LOW (0) during this transition period.
As
𝐴
A completes its transition to HIGH, the output of the NAND gate will go HIGH (1) again.
Output Pulse Generation:
The circuit can be designed such that the momentary LOW (0) output from the NAND gate, caused by the input transition of
𝐴
A, generates a pulse.
This pulse width is determined by the propagation delay
𝜏
τ of the inverters.
Subsequent transitions of
𝐵
B or
𝐴
A will create additional pulses, depending on their timing relative to each other and considering the propagation delays.
Summary:
The output of the pulse generator circuit will reflect the timing of the input transitions, modified by the propagation delays of the inverters.
Each transition of the inputs
𝐴
A and
𝐵
B can potentially generate a brief pulse at the output of the NAND gate, depending on their timing and the circuit design.
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