Patent ID: 7383296

Claim:
Apparatus for direct digital generation of a synthesized RF signal with phase modulation at a desired output frequency comprising: a high speed reference clock providing in an input signal having a series of signal reference edges at a frequency of the reference clock which is higher than the desired output frequency; programmable digital delay elements arranged to receive the reference edges of the input reference clock and to generate delayed signal edges each at a calculated delay from a respective reference edge; wherein the programmable digital delay elements include an input element for receiving an increment value defining the required phase modulation and providing a delay value for said calculated delay from said increment value; wherein the programmable digital delay elements comprises a high speed adders/accumulator which is arranged to determine the amount of delay implemented by the delay elements on the reference edge; and wherein the output frequency is set from the increment value according to the following equation: Increment Value=(( f ref /f out )−1)*2 n where f ref =Reference clock frequency f out =Output frequency n=Number of bits in the accumulator math; and a signal combining element for receiving the delayed signal edges and for generating the RF signal therefrom.