A fast chirp Phase Locked Loop with a phase preset includes a Voltage Controlled Oscillator, VCO, generating a Frequency Modulated Continuous Waveform, FMCW. The VCO responds to a filtered output voltage of a filter connected to a charge pump. A digital controller modifies the FMCW to generate a chirp phase and a return phase. The chirp phase includes a first linear change of the FMCW from a start frequency to a stop frequency. The return phase includes a second linear change of the FMCW from the stop frequency to the start frequency. A phase preset circuit connects to the digital controller and the filter. The phase preset circuit supplies a phase preset current during a start frequency time preceding the chirp phase. The phase preset current is proportional to a VCO gain of the VCO and inversely proportional to a chirp current during the chirp phase.

A frequency generator is disclosed. The frequency generator is for generating an oscillator clock according to a reference clock, and the frequency generator is used in a frequency hopping system that switches a carrier frequency among a plurality of channels, and the carrier frequency further carries a modulation frequency for data transmission. The frequency generator includes: a frequency hopping and modulation control unit, arranged for generating a current channel according to a channel hopping sequence and a frequency command word (FCW) based on the reference clock, a digital-controlled oscillator (DCO), arranged for to generating the oscillator clock according to an oscillator tuning word (OTW) obtained according to the estimated DCO normalization value. An associated method is also disclosed.

Upon external display configuration change, a graphics display driver or any suitable hardware or software modifies the clock frequency of the processor core (e.g., graphics processor core) display engine. The graphics display driver or any suitable hardware or software reprograms the core display clock PLL (CDCLK PLL) to a new frequency, without any dead clocks during such frequency change. A divide-by-2 divider changes the frequency of the PLL on the fly or dynamically. The technique may not require the PLL to be turned off and turned back again at all.

An electronic device may include wireless circuitry having mixer circuitry configured to receive oscillator signals from a partial-fractional phase-locked loop (PLL). The partial-fractional PLL may include a phase frequency detector, a charge pump, a loop filter, and a frequency divider connected in a loop. To implement the partial-fractional capability of the PLL, the frequency divider may receive a bitstream from a first order sigma delta modulator and a finite impulse response filter. The first order sigma delta modulator may output a periodic non-randomized output. The finite impulse response filter may increase the frequency of toggling of the periodic non-randomized output. Configured and operated in this way, the partial-fractional PLL can exhibit reduced phase noise.

An electronic device may include wireless circuitry having mixer circuitry configured to receive oscillator signals from a partial-fractional phase-locked loop (PLL). The partial-fractional PLL may include a phase frequency detector, a charge pump, a loop filter, and a frequency divider connected in a loop. To implement the partial-fractional capability of the PLL, the frequency divider may receive a bitstream from a first order sigma delta modulator and a finite impulse response filter. The first order sigma delta modulator may output a periodic non-randomized output. The finite impulse response filter may increase the frequency of toggling of the periodic non-randomized output. Configured and operated in this way, the partial-fractional PLL can exhibit reduced phase noise.

A clock circuit includes a set of level shifters, a duty cycle adjustment circuit and a calibration circuit. The set of level shifters is configured to output a first set of phase clock signals having a first duty cycle. The duty cycle adjustment circuit is configured to generate a first clock output signal responsive to a first phase clock signal, a second phase clock signal and a set of control signals, and adjust the second duty cycle responsive to the set of control signals or a phase difference between the first phase clock signal and the second phase clock signal. The calibration circuit is configured to perform a duty cycle calibration of a second duty cycle of the first clock output signal based on an input duty cycle, and to generate the set of control signals responsive to the duty cycle calibration.

A variable reactance apparatus, tunable oscillator and method for changing a gain associated with an input signal of a tunable oscillator are disclosed. An embodiment of the variable reactance apparatus includes a plurality of unit variable reactance structures including respective control input nodes, and a control circuit configured to connect each of the control input nodes to a respective signal from among a plurality of signals including a first tuning signal and a second tuning signal. An embodiment of a tunable oscillator includes a resonance circuit, a negative impedance structure and a variable reactance apparatus configured for tuning of the oscillator. An embodiment of a method includes altering connections of first and second tuning signals to control input nodes of respective first and second sets of unit variable reactance structures while holding constant a sum of the number of unit variable reactance structures in the first and second sets.

A signal generator has a nominal frequency control input and a modulation frequency control input and comprises an oscillator, with a first set of capacitors at least partially switchably connectable for adjusting a frequency of the oscillator as part of a phase-locked loop, and a second set of capacitors comprised in a modulation stage of the oscillator, switchably connectable for modulating the frequency and controlled by the modulation frequency control input; a modulation gain estimation stage configured to determine a frequency-to-capacitor modulation gain; and a modulation range reduction module configured for clipping a modulation range of the oscillator to a range achievable using the second set of capacitors, using the modulation gain averaging out, in time, a phase error caused by the said clipping; and mimicking the said clipping, additively output to the nominal frequency control input to compensate said PLL for the said modulation.

A reception apparatus communicating with a transmission apparatus with a clock lane and a data lane. The reception apparatus comprises a clock lane control circuit configured to determine the operation mode of the clock lane based on a clock signal transmitted through the clock lane, and performing an operation based on the determined operation mode of the clock lane, and a data lane control circuit configured to determine the operation mode of the data lane based on a data signal transmitted from the transmission apparatus, and performing an operation based on the determined operation mode of the data lane, and the clock lane control circuit is configured to set the operation mode of the clock lane to a high-speed mode, when the operation mode of the data lane is switched from a low-power mode to the high-speed mode.

Quadrature oscillator circuitry, comprising: a first differential oscillator circuit having differential output nodes and configured to generate a first pair of differential oscillator signals at those output nodes, respectively; a second differential oscillator circuit having differential output nodes and configured to generate a second pair of differential oscillator signals at those output nodes, respectively; and a cross-coupling circuit connected to cross-couple the first and second differential oscillator circuits. The cross-coupling circuit may comprise a pair of cross-coupled transistors.