Rohde and Schwarz Gmbh & Co. Kg

Ernst Polz

Alexander Roth

Juergen Rademacher

A phase coherent synthesizer with good phase noise and spurious performance is described. The phase coherent synthesizer includes digital direct synthesizer (DDS) circuitry, frequency multiplier circuitry, an oscillator, and a mixing stage. The digital direct synthesizer (DDS) circuitry has a first output and a second output. The first output is associated with a fine resolution synthesis. The second output is associated with a step synthesis. A second output signal provided via the second output has a higher frequency compared with a first output signal provided via the first output. The frequency multiplier circuitry is connected with the second output. The frequency multiplier circuitry is configured to multiply the second output signal received via the second output, thereby generating a multiplied output signal. The mixing stage has two input ports connected with the frequency multiplier circuitry and the oscillator respectively. The mixing stage includes, for example, circuitry configured to mix the multiplied output signal and an oscillator output signal of the oscillator, thereby generating an intermediate frequency signal. The first output signal and the intermediate frequency signal are synchronized with each other.

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Munich, Germany

Ernst Polz