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hamza		 How does a frequency synthesizer work? View All
It is obvious that F/synth. produces output frequencies which are multiples of input frequency.does these multiples remain constant for every corresponding input frequency?if so then how f/synthesis is achieved,if not then explain.
16 years ago - 9 months left to answer. - 1 response - Report Abuse
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richards
 Devices called 'phase-locked-loops' are used in some types of synthesizers (like the ones you are thinking of). Usually the input signal is converted from a sine-wave to a square-wave of the same frequency, whose voltage level is the same as the digital logic level used in the rest of the circuit.

Using digital multipliers, digital dividers, and filters, many different frequencies may be generated from the input frequency, all phase-locked to the input signal. The output synthesized frequencies may be higher or lower than the input frequency.

For example, if the multiplier had a 4-bit register, then you could get multiples from 1x to 16x of the input frequency. If the divider had a 16-bit register, then you could get divisions from x/1 to x/65536 of the input. Combining the two, you can get any combination (i.e. 5/24591 of the input frequency).

Another type of frequency synthesizer uses a direct approach. A sequencer (microprocessor, logic state machine) feeds digital numbers,

16 years ago

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