Frequency synthesizer and frequency synthesizing method

Abstract

The present invention relates to a frequency synthesizer comprising a main unit and a side unit. The main unit comprises a main phase detector to obtain a main control signal, a main oscillator that generates a main synthesized frequency output signal representing the frequency synthesizer output signal based on said main control signal, and a mixer that mixes said main synthesized frequency output signal with a side synthesized frequency output signal to obtain said mixer output signal. The side unit generates said side synthesized frequency output signal and comprises a frequency signal generation unit that provides a linear frequency sweep signal or a fixed-frequency control signal at a fine frequency resolution from said fixed-frequency side reference signal, and a side oscillator that generates said side synthesized frequency output signal based on said frequency sweep signal or said fixed-frequency control signal.

Description

technical field

[0001] The invention relates to a frequency synthesizer and a corresponding frequency synthesis method. Background technique

[0002] A frequency synthesizer is a key building block of any microwave system. They can be found in many modern devices including radio receivers, mobile phones, satellite receivers, GPS systems, radars, and more. There are three main synthesizer architectures, specifically direct analog synthesizers, direct digital synthesizers, and indirect (phase-locked loop) synthesizers. Microwave systems have increasingly stringent requirements, such that known synthesizers cannot meet requirements such as phase noise, switching speed, fine resolution and frequency sweep. Recently, new hybrid architectures combining a direct digital synthesizer (DDS) with a phase-locked loop (PLL) have been developed, however, this still cannot satisfy all these requirements.

[0003] US 7,250,823 discloses a Direct Digital Synthesis (DDS) Phase Locked Loop ...

Examples

Embodiment Construction

[0045] figure 1Shown for example as Stelzer, A.; Kolmhofer, E.; Scheiblhofer, S.;, "Fast 77GHz chirps with direct digital synthesis and phase locked loop", Microwave Conference Proceedings, 2005, APMC 2005, Asia-Pacific Conference Proceedings, vol.3 A first embodiment of the hybrid DDS / PLL frequency synthesizer 10 described in , 4-7 Dec.2005. The frequency synthesizer comprises a DDS (Direct Digital Synthesizer) 14 which receives a reference signal from a reference signal source 12 and which in turn is used for a reference input of a phase detector 16 . A phase detector 16 (also referred to as a phase-frequency detector) detects the frequency difference and phase difference between the reference signal from the DDS 14 and the feedback signal from the feedback loop. A loop filter 18 is coupled to the output of phase detector 16 for filtering the control signal output from phase detector 16 . A controlled oscillator 20, such as a voltage controlled oscillator (VCO), is coupled...

technical field

[0001] The invention relates to a frequency synthesizer and a corresponding frequency synthesis method. Background technique

[0002] A frequency synthesizer is a key building block of any microwave system. They can be found in many modern devices including radio receivers, mobile phones, satellite receivers, GPS systems, radars, and more. There are three main synthesizer architectures, specifically direct analog synthesizers, direct digital synthesizers, and indirect (phase-locked loop) synthesizers. Microwave systems have increasingly stringent requirements, such that known synthesizers cannot meet requirements such as phase noise, switching speed, fine resolution and frequency sweep. Recently, new hybrid architectures combining a direct digital synthesizer (DDS) with a phase-locked loop (PLL) have been developed, however, this still cannot satisfy all these requirements.

[0003] US 7,250,823 discloses a Direct Digital Synthesis (DDS) Phase Locked Loop ...

Examples

Embodiment Construction

[0045] figure 1Shown for example as Stelzer, A.; Kolmhofer, E.; Scheiblhofer, S.;, "Fast 77GHz chirps with direct digital synthesis and phase locked loop", Microwave Conference Proceedings, 2005, APMC 2005, Asia-Pacific Conference Proceedings, vol.3 A first embodiment of the hybrid DDS / PLL frequency synthesizer 10 described in , 4-7 Dec.2005. The frequency synthesizer comprises a DDS (Direct Digital Synthesizer) 14 which receives a reference signal from a reference signal source 12 and which in turn is used for a reference input of a phase detector 16 . A phase detector 16 (also referred to as a phase-frequency detector) detects the frequency difference and phase difference between the reference signal from the DDS 14 and the feedback signal from the feedback loop. A loop filter 18 is coupled to the output of phase detector 16 for filtering the control signal output from phase detector 16 . A controlled oscillator 20, such as a voltage controlled oscillator (VCO), is coupled...

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