Exams › GATE › Technical
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). The free-running frequency of the PLL is set to 20 kHz. Assume that the commutator switch makes contacts repeatedly in the order 1-2-3-4. The corresponding frequencies synthesized are:
- 10 kHz, 20 kHz, 40 kHz, 80 kHz
- 20 kHz, 40 kHz, 80 kHz, 160 kHz
- 80 kHz, 40 kHz, 20 kHz, 10 kHz
- 160 kHz, 80 kHz, 40 kHz, 20 kHz
Correct answer: 160 kHz, 80 kHz, 40 kHz, 20 kHz
Solution
The correct option is right because the divide-by-N counter outputs frequencies that are derived from the PLL's free-running frequency of 20 kHz. By dividing this frequency by 1, 2, 4, and 8, we obtain the synthesized frequencies of 20 kHz, 40 kHz, 80 kHz, and 160 kHz, respectively, in the order specified.
Related GATE Technical questions
- Which one of the following is an eigen function of the class of all continuous-time, linear, time-invariant systems (u(t) denotes the unit-step function)?
- A continuous-time function x(t) is periodic with period T. The function is sampled uniformly with a sampling period Tₛ. In which one of the following cases is the sampled signal periodic?
- Consider the sequence x[n] = aⁿ u[n] + bⁿ u[n], where u[n] denotes the unit-step sequence and 0 < |a| < |b| < 1. The region of convergence (ROC) of the z-transform of x[n] is
- Consider a two-port network with the transmission matrix: T = [[A, B],[C, D]]. If the network is reciprocal, then
- Consider the following statements for a metal oxide semiconductor field effect transistor (MOSFET):
P: As channel length reduces, OFF-state current increases.
Q: As channel length reduces, output resistance increases.
R: As channel length reduces, threshold voltage remains constant.
S: As channel length reduces, ON current increases.
Which of the above statements are INCORRECT?
- The three-dimensional state of stress at a point is given by σ = [[10, 0, 0],[0, 40, 0],[0, 0, 0]] MPa. The maximum shear stress at the point is
⚔️ Practice GATE Technical free + battle 1v1 →