13-07-2012, 11:50 AM
Frequency and Time Synthesis A Tutorial
Frequency and Time Synthesis-a Tutorial.ppt (Size: 845.5 KB / Downloads: 79)
Frequency and Time SynthesisTutorial Organization
Basic Concepts
What is a Synthesizer?
Basic Concepts of Frequency and Time Synthesis
Direct Analog Synthesis
Analog Building Blocks
(Digital Building Blocks used to Generate Frequencies)
No VCO’s
Indirect Synthesis
Uses Phase or Frequency Locked VCOs
Direct Digital Synthesis
Uses Digital Processing Techniques to Generate Output
Digital Circuits used to Process Numbers
No VCO’s
Ideal Coherent Synthesizer
Coherent Frequency Translation by Factor K
Multiplies the Input Frequency fr by a Factor K
Ideal: Doesn’t Add Noise
Input Phase Error fr Also Multiplied by K
The Phase Error Integral of the Angular Frequency Error
The y and x of a Reference Oscillator are Independent of the Final Output Frequency
Spectral Density Review
A Random Variable u(t) is Wide Sense Stationary if the Autocorrelation Function R is only a Function of t Ru(t) = T-1T u(t+t)u(t) dt
The Spectral Density is the Fourier Transform of Ru(t) Su(f) = ej2pft Ru(t) dt
For Frequency Translation K