1 / 7

k 0

A VCO has a free-running frequency of 120 Mhz and sensitivity (gain) of 20 kHz/v. Assume linear operation over an input range of +/- 5 volts. a. Draw plot of the VCO operating characteristic.

step
Télécharger la présentation

k 0

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. A VCO has a free-running frequency of 120 Mhz and sensitivity (gain) of 20 kHz/v. Assume linear operation over an input range of +/- 5 volts. • a. Draw plot of the VCO operating characteristic. • b. The input is vi(t) = 2.5 cos(wmt), where wm = 104 r/s. What is the output vo(t) = ? • c. What is the modulation index for part b? • d. Indicate the operating region on your plot from part a. • e. Draw a block diagram for the device suitable for use in system analysis. + vm(s) k0 fout(s) + f0

  2. + kd vout(s) fin(s) _ fd A frequency discriminator has a crossover frequency of 80 Mhz and sensitivity (gain) of 5.0 v/Mhz. a. Draw plot of the discriminator operating characteristic. b. The input is vi(t) = 2.5 cos(wmt), where wm = 0.5 x 109 r/s. What is vo(t) = ? c. Indicate the operating region on your plot from part a. (You choose, > +/- 2.1 v) d. Draw a block diagram for the device suitable for use in system analysis.

  3. Phase Locked Loops Loop Filter VCO Input kF : v/rad kv : rad/s/v VCO + + kF _ + Phase Detector - + _

  4. Frequency Error Phase Error - + + _ • Simple example: uncompensated loop • H(s) = 5 = kA • kF = 0.1 v/rad • ko = 60p x 103 rad/s/v • DwI = -10 khz = -20,000p rad/s F(s) is forward gain from input to point of interest. Frequency Error: F(s) = 1 Steady State Response = 0 Surprise! Phase Error: F(s) = 1/s VCO Voltage: F(s) = 0.5/s

  5. Dynamic response: For step change in input frequency DwI, X(s) = DwI /s Frequency Error: F(s) = 1 Phase Error: F(s) = 1/s Hold in Range: Phase error

  6. FM Application Vout(s) - + + _

  7. FSK Application fFR = 3.5 khz fMARK = 2 kHz fSPACE= 4 kHz BR = 1333 Bit/s tBIT = 0.75 ms

More Related