Embodiments described herein relate to a 50%-duty-cycle consecutive integer frequency divider and a phase-locked loop circuit having the frequency divider. The frequency divider includes a consecutive integer frequency divider module having a non-50%-duty-cycle, wherein the module receives a clock signal CLK and an input control signal CB and outputs a consecutive frequency division clock signal CLK1 comprising a non-50% duty cycle; a D flip-flop module for receiving the clock signal CLK and the consecutive frequency division clock signal CLK1 and outputting at least one clock signal CLKx; and a logic OR gate module for receiving the consecutive frequency division clock signal CLK1 and the at least one clock signal CLKx, and outputting an output clock signal CLKout comprising a 50% duty cycle.

A phase-locked loop (PLL) for a radar system includes an oscillator configured to have an output frequency and a multi-modulus divider (MMD) configured to implement successive frequency modulation ramps of the oscillator output frequency, each frequency modulation ramp beginning at a first frequency and ending at a second frequency. The PLL is operated by downmixing an output of the MMD to a frequency above zero Hertz, measuring the downmixed output of the MMD to generate a plurality of MMD output measurements for each frequency modulation ramp, and calculating the frequency of the MMD based on the plurality of MMD output measurements for each frequency modulation ramp.

A system and method to dynamically control a reset signal for an IQ divider are provided. The system includes an IQ divider configured to output a IQ divider output clock; an input configured to receive a reference clock; a failure sensing circuit configured to sense a failure in the IQ divider output clock, the failure sensing circuit including an automatic frequency calibration (AFC) logic; and a control circuit configured to control a reset signal provided to the IQ divider, based on an output of the failure sensing circuit corresponding the failure sensed by the failure sensing circuit.

A system and method to dynamically control a reset signal for an IQ divider are provided. The system includes an IQ divider configured to output a IQ divider output clock; an input configured to receive a reference clock; a failure sensing circuit configured to sense a failure in the IQ divider output clock, the failure sensing circuit including an automatic frequency calibration (AFC) logic; and a control circuit configured to control a reset signal provided to the IQ divider, based on an output of the failure sensing circuit corresponding the failure sensed by the failure sensing circuit.

An apparatus is described that, according to an exemplary embodiment, has an RF oscillator for generating an RF oscillator signal at a first frequency and a frequency divider having a division ratio that is fixed during operation. The frequency divider is supplied with the RF oscillator signal and is configured to provide an oscillator signal at a second frequency. The apparatus further has a monitor circuit, to which the oscillator signal at the second frequency is supplied and which is configured to measure the second frequency and to provide at least one digital value that is dependent on the second frequency of the oscillator signal. The at least one digital value is provided on a test contact.

An apparatus is described that, according to an exemplary embodiment, has an RF oscillator for generating an RF oscillator signal at a first frequency and a frequency divider having a division ratio that is fixed during operation. The frequency divider is supplied with the RF oscillator signal and is configured to provide an oscillator signal at a second frequency. The apparatus further has a monitor circuit, to which the oscillator signal at the second frequency is supplied and which is configured to measure the second frequency and to provide at least one digital value that is dependent on the second frequency of the oscillator signal. The at least one digital value is provided on a test contact.

Disclosed herein is an apparatus that includes a variable clock divider configured to divide a first clock signal to generate a second clock signal, a delay circuit configured to delay the second clock signal to generate a third clock signal, and a phase detector configured to compare phases of the second and third clock signals. The variable clock divider has a division ratio that is variable based, at least in part, on a delay amount of the delay circuit.

Disclosed herein is an apparatus that includes a variable clock divider configured to divide a first clock signal to generate a second clock signal, a delay circuit configured to delay the second clock signal to generate a third clock signal, and a phase detector configured to compare phases of the second and third clock signals. The variable clock divider has a division ratio that is variable based, at least in part, on a delay amount of the delay circuit.

Systems, methods, and circuitries are provided for resonator-based local oscillator signal generation for receiving self-interference signals. An interference cancellation system for a transceiver includes a resonator configured to generate a high-frequency signal and a local oscillator circuitry. The local oscillator circuitry includes a digital-to time converter configured to receive the high-frequency signal and, in response, generate a clock signal for receiving an interfering signal having an interference frequency. Digital cancellation circuitry is configured to adapt operation of the transceiver based, at least in part, on the received interfering signal.

Methods and apparatuses are provided for fractional-N frequency synthesis using a phase-locked loop (PLL). A phase detector (PD) of the PLL determines a phase difference between a clock and a feedback clock (CLKFB). A low-pass loop filter of the PLL detects a control voltage based on the phase difference. A voltage-controlled oscillator (VCO) of the PLL generates a periodic signal based on the control voltage. A sigma-delta modulator (SDM) of the PLL generates a division sequence ratio and a selection control signal based on a frequency command word. A multi-modulus divider (MMDIV) generates a first CLKFB and a second CLKFB based on the division sequence ratio and differential inputs of the periodic signal. The MMDIV outputs one of the first CLKFB and the second CLKFB as the CLKFB to the PD based on the selection control signal.