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 or autonomous vehicle is also disclosed.

A frequency synthesiser arrangement is arranged to receive a clock input signal and provide an output signal. The frequency synthesiser arrangement comprises: a frequency divider arranged to divide the output signal by a variable number N and output a feedback signal; a phase detector arranged to detect a phase difference between the feedback signal and the clock input signal; a phase alignment circuit portion arranged to determine an overlap of the clock input signal and the feedback signal; and a voltage controlled oscillator which is arranged to receive either a first input derived from the phase detector or a second input from an external reference voltage and to provide the output signal. The phase alignment circuit portion is arranged to provide a control output which determines whether the voltage controlled oscillator receives the first or second input.

A phase lock loop (PLL) includes a voltage-controlled oscillator (VCO) and a frequency detector to generate a FAST signal responsive to a frequency of a reference signal being greater than the frequency of a feedback signal derived from the VCO and to generate a SLOW signal responsive to the frequency of the reference signal being smaller than the frequency of the feedback signal. The PLL also includes a digital charge pump, a loop filter, and a state machine circuit. Responsive to receipt of multiple consecutive FAST signals when the digital charge pump is providing a charging current to the loop filter, the state machine circuit reconfigures the digital charge pump to increase the charging current to the loop filter. Responsive to receipt of multiple consecutive SLOW signals when the loop filter is discharging, the state machine circuit reconfigures the digital charge pump to cause the loop filter's discharge current to increase. Upon detection of a terminal condition, the state machine circuit may disable the digital charge pump and enable operation of an analog charge pump.

Embodiments herein describe a reference-less CDR circuit that receives electrical signals that may have been transmitted along either an electrical or optical interconnect which are then processed to identify the original data. To do so, the CDR circuit includes a frequency locking loop (FLL) and a phase locking loop (PLL) which generate control signals for a voltage controlled oscillator (VCO). In one embodiment, the FLL generates a coarse adjustment signal which the VCO uses to output a recovered clock that substantially matches the frequency of the received electrical signal. The PLL, on the other hand, generates a fine adjustment signal which the VCO uses to make small adjustments (e.g., half cycle phase shifts) to the recovered clock. The recovered clock outputted by the VCO is then fed back and used as an input in both the FLL and the PLL.

A frequency generator for generating a controlled signal having a controlled frequency uses a frequency ratio generator with an input; a frequency divider for dividing the controlled frequency by a frequency ratio signal to generate a divided signal having a divided frequency; a converter for generating an excitation signal having the divided frequency, the excitation signal exciting a resonator for generating a resonance signal having a resonance frequency; a frequency phase detector of a phase difference between the divided frequency and the resonance frequency; an inner loop filter for generating the frequency ratio signal and filtering the phase difference signal to prevent instability of two frequency ratio generator loops; an output configured for providing the frequency ratio signal based on a ratio between the controlled frequency and the resonance frequency; and a controlled oscillator circuit for generating the controlled signal based on comparison of the frequency ratio with a target ratio.

An apparatus of a mobile device may calibrate RF circuitry for mobile communications. The apparatus may include phase locked loop (PLL) comprising a digital controlled oscillator (DCO) and one or more processors coupled to the PLL. The one or more processors may determine a coarse tuning setting for the DCO based on a target frequency of a wireless channel; and calculate, a DCO gain value for the coarse tuning setting based on a calibration DCO gain value for a calibration coarse tuning setting.

A sub-sampling phase-locked loop is described, which comprises a digital-to-time converter, a sampler module, an interpolator, and a voltage controlled oscillator. The digital-to-time converter is configured to provide a first delay signal (S.sub.DLY1) at a first point (t.sub.1) in time and a second delay signal (S.sub.DLY2) at a second point in time (t.sub.2). The sampler module is configured to provide a first sample (S.sub.1) of the oscillator output signal (S.sub.OUT) at the first point in time (t.sub.1) and a second sample (S.sub.2) of the oscillator output signal (S.sub.OUT) at the second point in time (t.sub.2). The interpolator is configured to provide a sampler signal (S.sub.SAMPL) by interpolating the first sample (S.sub.1) and the second sample (S.sub.2). The voltage controlled oscillator is configured to control the oscillator output signal (S.sub.OUT) based on the sampler signal (S.sub.SAMPL).

A frequency synthesizing device includes a voltage-controlled oscillator receiving an adjusting signal and generating an output signal according to the adjusting signal. A feedback frequency divider having a plurality of divisor values receives the output signal and generates a feedback signal after performing frequency dividing. An automatic frequency calibration circuit of the frequency synthesizing device includes a first frequency divider receiving a reference frequency, and a second frequency divider receiving the feedback signal. A comparator of the automatic frequency calibration circuit receives and compares outputs from the first frequency divider and the second frequency divider in a predetermined period to generate a comparing result. A state machine outputs the adjusting signal according to the comparing result in a calibration mode.

The CDR (Clock Data Recovery) device may include at least one or more CDR channels configured to receive input data stream; and a global clock generator configured to provide a frequency locked clock to each of the at least one or more CDR channels, wherein each of the at least one or more CDR channels creates a reference clock signal for the global clock generator.

The CDR (Clock Data Recovery) device may include at least one or more CDR channels configured to receive input data stream; and a global clock generator configured to provide a frequency locked clock to each of the at least one or more CDR channels, wherein each of the at least one or more CDR channels creates a reference clock signal for the global clock generator.