# Timers Gate Questions | Analog Circuits

 Question 1
The block diagram of a frequency synthesizer consisting of a Phase Locked Loop (PLL) and a divide-by-N counter (comprising ÷2, ÷4, ÷8, ÷16 outputs) is sketched below. The synthesizer is excited with a 5 kHz signal (Input 1). The free-running frequency of the PLL is set to20 kHz. Assume that the commutator switch makes contacts repeatedly in the order 1-2-3-4. The corresponding frequencies synthesized are:
 A 10 kHz, 20 kHz, 40 kHz, 80 kHz B 20 kHz, 40 kHz, 80 kHz, 160 kHz C 80 kHz, 40 kHz, 20 kHz, 10 kHz D 160 kHz, 80 kHz, 40 kHz, 20 kHz
Question 1 Explanation:
 Question 2
In the Astable multivibrator circuit shown in the figure, the frequency of oscillation (in kHz) at the output pin 3 is ___________
 A Fill in the Blank Type Question
Question 2 Explanation:
 Question 3
The circuit shown represents:
 A A bandpass filter B A voltage controlled oscillator C An amplitude modulator D A monostable multivibrator
Question 3 Explanation:
A monostable multivibrator
A monostable multivibrator, also called a one shot, is a sequential logic electronic circuit that generates an output pulse. When triggered, a pulse of pre-defined duration is produced. The circuit then returns to its stable state and produces no more output until triggered again.
 Question 4
The two advantages of FIR filters over IIR- filters are.
 A they are guaranteed to be stable and non-linear B they are marginally stable and linear. C they are guaranteed to be stable and may be constrained to have linear phase D they are marginally stable and non-linear
Question 4 Explanation:
IIR filters are recursive and FIR filters are non-recursive. Also FIR filters are linear phase and IIR filters are not; several applications are sensitive to non-linear phase (communications, medical, etc). In implementation, IIR filters require fewer taps (smaller order) and thusly are easier to implement and have fewer zeros. Also FIR filters are always stable, while IIR filters can often become unstable in implementation. Digital filters with finite-duration impulse response (all-zero, or FIR filters) have both advantages and disadvantages compared to infinite-duration impulse response (IIR) filters.
FIR filters have the following primary advantages:
• They can have exactly linear phase.
• They are always stable.
• The design methods are generally linear.
• They can be realized efficiently in hardware.
• The filter startup transients have finite duration.
The primary disadvantage of FIR filters is that they often require a much higher filter order than IIR filters to achieve a given level of performance. Correspondingly, the delay of these filters is often much greater than for an equal performance IIR filter.
There are 4 questions to complete.