A lock detector (8) detects an unlocked state from an output of a phase frequency comparator (1). A counter (9) counts a reference signal, in a case where an unlocked state is detected by the lock detector (8). A parameter controlling circuit (10) acquires the count value of the counter (9), and controls switching on and off of a switch (12) for a D/A converter (11) that generates a signal to be added to an output of a loop filter (3), and the output voltage of the D/A converter (11) so that the count value of the counter (9) falls within a set value.

Method and apparatus for determining a clock frequency for an electronic processor are provided. One embodiment provides a clock generator for determining a clock frequency for an electronic processor and providing a clock signal to the electronic processor. The clock generator includes a crystal oscillator producing a reference signal and a phase locked loop receiving the reference signal and configured to generate the clock signal based on the reference signal. The clock generator also includes a tuning logic controller electrically coupled to the phase locked loop. The tuning logic controller is configured to program the phase locked loop to a first frequency and determine an integrated circuit process corner of the electronic processor. The tuning logic controller is also configured to determine a second frequency based on the integrated circuit process corner and program the phase locked loop to the second frequency.

An RF circuit comprises a charge pump configured to generate current pulses having a first current amplitude and a predetermined duration; and a capacitive element configured to receive the current pulses and to generate a tuning voltage depending thereon. An RF oscillator is configured to generate an RF signal having a frequency that is dependent on the tuning voltage. The RF circuit comprises a measuring circuit configured to generate a measurement signal representing the tuning voltage or the frequency of the RF signal. A controller circuit is configured to drive the charge pump in order to change the first amplitude of a current pulse by a current difference, and ascertain a first change in the measurement signal and a second change in the measurement signal. A measurement value for the first amplitude can be calculated based on the first change and the second change based on the current difference.

Disclosed herein is a tunable resonant circuit including an inductance directly electrically connected in series between first and second nodes, a variable capacitance directly electrically connected between the first and second nodes, and a set of switched capacitances coupled between the first and second nodes. The set of switched capacitances includes a plurality of capacitance units, each capacitance unit comprising a first capacitance for that capacitance unit directly electrically connected between the first node and a switch and a second capacitance for the capacitance unit directly electrically connected between the switch and the second node. Control circuitry is configured to receive an input control signal and connected to control the switches of the set of switched capacitances. A biasing circuit is directly electrically connected to the tunable resonance circuit at the first and second nodes.

A PFD outputs a detection signal based on a phase difference or a frequency difference between a reference signal and a feedback signal, a charge pump circuit outputs a pulse signal based on the detection signal, and a loop filter outputs a control voltage based on the pulse signal. A VCO includes a ring oscillator where a plurality of delay element units, which include a plurality of delay elements (for example, inverter circuits) connected in parallel, are connected in series in a ring, controls the frequency of the output signal of the ring oscillator based on the control voltage, and controls the phase of the output signal of the ring oscillator by controlling the active number of delay elements, out of the plurality of delay elements, based on the detection signal. A frequency divider circuit generates and outputs a feedback signal by dividing the frequency of the output signal.

An RF circuit comprises a charge pump configured to generate current pulses having a first current amplitude and a predetermined duration; and a capacitive element configured to receive the current pulses and to generate a tuning voltage depending thereon. An RF oscillator is configured to generate an RF signal having a frequency that is dependent on the tuning voltage. The RF circuit comprises a measuring circuit configured to generate a measurement signal representing the tuning voltage or the frequency of the RF signal. A controller circuit is configured to drive the charge pump in order to change the first amplitude of a current pulse by a current difference, and ascertain a first change in the measurement signal and a second change in the measurement signal. A measurement value for the first amplitude can be calculated based on the first change and the second change based on the current difference.

A lock detector (8) detects an unlocked state from an output of a phase frequency comparator (1). A counter (9) counts a reference signal, in a case where an unlocked state is detected by the lock detector (8). A parameter controlling circuit (10) acquires the count value of the counter (9), and controls switching on and off of a switch (12) for a D/A converter (11) that generates a signal to be added to an output of a loop filter (3), and the output voltage of the D/A converter (11) so that the count value of the counter (9) falls within a set value.

A flash analog-to-digital converter (ADC) receives an input control signal and performs coarse tuning of a frequency of an output signal, produced between first and second nodes having an inductance coupled therebetween. The flash ADC quantizes an operating frequency range for the output signal produced between the first and second nodes as M.Math.?f, where M is an integer from 0 to N?1, where N is a number of intervals into which a frequency range for the output signal is divided, and where ?f is a resulting frequency step produced by the quantizing. The value of M is generated based upon the input control signal and a word controlling switches of a plurality of switched capacitance circuits associated with the first and second nodes to close ones of those switches associated with the control word to coarsely tune the frequency of the output signal.

A local oscillator generator (LO generator) may be configured to transmit an LO signal to a mixer. The LO generator may include an input buffer configured to generate a first internal oscillator signal based on the input oscillator signal. The LO generator may include a frequency dividing circuit configured to generate a second internal oscillator signal based on dividing a frequency of the first internal oscillator signal. The LO generator may include an output buffer configured to generate the LO signal based on the second internal oscillator signal. The input buffer and the frequency dividing circuit may each be configured to receive a power voltage independently of the output buffer.

The present invention relates to a voltage controlled oscillator and phase locked loop comprising the same for compensating a noise of a power voltage. According to an embodiment of the present invention, a voltage controlled oscillator may comprise: an oscillator comprising a plurality of inverters connected as a ring form for generating a plurality of signals having different phases with each other, and a plurality of feed forward circuits formed between the inverters; and a controller for controlling the inverter and feed forward circuit based on a detected noise by detecting a noise of a power voltage.