Problems on J-K 1.1

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A J-K flip-flop with J =1 and K =1 has 20kHz clock input.

The Q output is _____

(a)constantly LOW

(b)constantly HIGH

(c)a 20kHz square wave

(d)a 10kHz square wave

Answer is (d)

Concept

• Flip-flops change their state only when triggered(either by positive edge/negative edge)
• Assume positive edge triggered J-K flip-flop

Clk(in)= 20kHz=> 1/20kHz = 0.05ms
Therefore, output frequency = 1/0.1ms = 10kHz