A frequency synthesis device with high multiplication rank, including a base frequency generator generating two first base signals of square shape of same frequency and opposite to each other, a first synthesis stage including two first switching power supply oscillators, of which the power supplies are respectively switched by the two first base signals, a second synthesis stage including a second switching power supply oscillator of which the supply is switched by a combination of the output signals of the two first oscillators, the output of the second switching power supply oscillator being filtered by a frequency discriminator circuit realized with an injection locked oscillator.

A multi-tone multi-band tunable millimeter-wave synthesizer is provided. In some embodiments, the multi-tone multi-band tunable millimeter-wave synthesizer is configured to simultaneously generate multiple frequency tones for space-borne beacon transmitter for atmospheric radio wave propagation studies. The apparatus includes a comb generator, which puts out evenly spaced harmonic frequencies of the input signal, which are coherent, tunable, and the number of tones or combs is scalable over a wide range of frequencies. These harmonics or tones are amplified to the power level needed for radio wave propagation studies. The amplified signals are transmitted as beacon signals from a satellite to a ground receiving station.

A multi-tone multi-band tunable millimeter-wave synthesizer is provided. In some embodiments, the multi-tone multi-band tunable millimeter-wave synthesizer is configured to simultaneously generate multiple frequency tones for space-borne beacon transmitter for atmospheric radio wave propagation studies. The apparatus includes a comb generator, which puts out evenly spaced harmonic frequencies of the input signal, which are coherent, tunable, and the number of tones or combs is scalable over a wide range of frequencies. These harmonics or tones are amplified to the power level needed for radio wave propagation studies. The amplified signals are transmitted as beacon signals from a satellite to a ground receiving station.

This disclosure provides systems, methods, and devices for wireless communications that support downconversion of signals with improved harmonic rejection. In a first aspect, an apparatus includes a first plurality of mixers with each mixer coupled to two oscillating signals that are 180 degrees apart in phase; a second plurality of mixers with each mixer coupled to two oscillating signals that are 180 degrees apart in phase, wherein a combined load of the first plurality of mixers and the second plurality of mixers on the plurality of oscillating signals is symmetric as to each oscillating signal of the plurality of oscillating signals; and a shared capacitor coupling the RF input to the first plurality of mixers and the second plurality of mixers. Other aspects and features are also claimed and described.

This disclosure provides systems, methods, and devices for wireless communications that support downconversion of signals with improved harmonic rejection. In a first aspect, an apparatus includes a first plurality of mixers with each mixer coupled to two oscillating signals that are 180 degrees apart in phase; a second plurality of mixers with each mixer coupled to two oscillating signals that are 180 degrees apart in phase, wherein a combined load of the first plurality of mixers and the second plurality of mixers on the plurality of oscillating signals is symmetric as to each oscillating signal of the plurality of oscillating signals; and a shared capacitor coupling the RF input to the first plurality of mixers and the second plurality of mixers. Other aspects and features are also claimed and described.

A signal generator. A voltage controlled oscillator generates a signal that is fed to a comb generator, e.g., a nonlinear transmission line. A tone, from among a comb of tones at the output of the comb generator, is selected by a bandpass filter, its frequency is divided, e.g., by a direct digital synthesizer, and the result is compared, e.g., by a phase and frequency detector that receives a reference signal at its other input. The output of the phase and frequency detector is fed back, e.g., through a lowpass filter, to the voltage controlled oscillator.

A signal generator. A voltage controlled oscillator generates a signal that is fed to a comb generator, e.g., a nonlinear transmission line. A tone, from among a comb of tones at the output of the comb generator, is selected by a bandpass filter, its frequency is divided, e.g., by a direct digital synthesizer, and the result is compared, e.g., by a phase and frequency detector that receives a reference signal at its other input. The output of the phase and frequency detector is fed back, e.g., through a lowpass filter, to the voltage controlled oscillator.

The disclosed embodiments relate to a system that controls a phase-locked loop (PLL), eliminating harmonic locking issues during subsampling operation and achieving better noise performance. During operation, the system performs a procedure to measure a first duty cycle that indicates a relationship between a reference signal, which has a frequency F.sub.REF, and a voltage-controlled oscillator (VCO) output signal, which has a frequency F.sub.VCO and is generated by a VCO. The system also performs the procedure to measure a second duty cycle that indicates a relationship between a second reference signal (with a frequency of c*F.sub.REF) and the VCO-output signal. Next, the system determines a frequency and phase relationship between the reference signal and the VCO-output signal based on the first and second duty cycles. Finally, the system uses the frequency and phase relationship to adjust the VCO so that the VCO-output signal, which is used as an output of the PLL, is frequency and phase aligned with the reference signal.

The disclosed embodiments relate to a system that controls a phase-locked loop (PLL), eliminating harmonic locking issues during subsampling operation and achieving better noise performance. During operation, the system performs a procedure to measure a first duty cycle that indicates a relationship between a reference signal, which has a frequency F.sub.REF, and a voltage-controlled oscillator (VCO) output signal, which has a frequency F.sub.VCO and is generated by a VCO. The system also performs the procedure to measure a second duty cycle that indicates a relationship between a second reference signal (with a frequency of c*F.sub.REF) and the VCO-output signal. Next, the system determines a frequency and phase relationship between the reference signal and the VCO-output signal based on the first and second duty cycles. Finally, the system uses the frequency and phase relationship to adjust the VCO so that the VCO-output signal, which is used as an output of the PLL, is frequency and phase aligned with the reference signal.

An object detection system for autonomous vehicle, comprising a radar unit and at least one ultra-low phase noise frequency synthesizer, is provided. The radar unit configured for detecting the presence and characteristics of one or more objects in various directions. The radar unit may include a transmitter for transmitting at least one radio signal; and a receiver for receiving the at least one radio signal returned from the one or more objects. The ultra-low phase noise frequency synthesizer may utilize Clocking device, Sampling Reference PLL, at least one fixed frequency divider, DDS and main PLL to reduce phase noise from the returned radio signal. This proposed system overcomes deficiencies of current generation state of the art Radar Systems by providing much lower level of phase noise which would result in improved performance of the radar system in terms of target detection, characterization etc. Further, a method for autonomous vehicle is also disclosed.