A signal generator according to the invention includes: a reference signal source configured to output a clock signal; a phase locked loop (PLL) circuit configured to generate a chirp signal as a feedback loop type circuit including a frequency divider using the clock signal; and a linearity-improvement processor configured to detect a frequency of a chirp signal of an M-th period generated by the PLL circuit where M is an integer greater than or equal to 1, and to control a division ratio of the frequency divider such that a difference between a frequency of a chirp signal generated in (M+1)-th and subsequent periods in the PLL circuit and a desired frequency becomes smaller than a difference between the detected frequency and the desired frequency.

Multi-phase clock generation employing phase error detection between multiple delay circuit outputs in a controlled delay line to provide error correction is disclosed. A multi-phase clock generator is provided that includes a controlled delay line and a phase error detector circuit. Tap nodes are provided from outputs of one or more delay circuits in the controlled delay line. To detect and correct for phase errors in the controlled delay line, a phase detection circuit is provided that includes at least two phase detectors each configured to measure a phase offset error between tap nodes from the delay circuit(s) in the controlled delay line. These phase errors are then combined to create an error correction signal, which is used to control the delay of the delay circuit(s) in the controlled delay line to lock the phase of the output of the final delay circuit to an input reference clock signal.

Systems and methods are provided in which an offset phase-locked loop (PLL) system can be configured as part of a radio frequency transmitter. The PLL can include a phase detection circuit including a first input configured to receive an information signal and a second input configured to receive a feedback signal; a charge pump including an input coupled to the phase detection circuit and an output; a filter including an input coupled to the output of the charge pump; a voltage-controlled oscillator coupled to the charge pump and including an LC tank circuit comprising an inductive element and a capacitive element, wherein the inductive element of the LC tank circuit comprises the antenna; and a feedback path.

The programmable frequency control system presented herein provides frequency programmability and phase noise reduction for signals generated by a plurality of frequency programmable phase-locked loops (PLLs). In general, a modulated data stream input to each of the plurality of PLLs controls the frequency of the signal output by the PLLs. The solution presented herein reduces the phase noise by introducing a time shift to the modulated data stream applied to at least some of the PLLs so that at least some of the PLLs receive time-shifted versions of the modulated data stream relative to other PLLs. In so doing, the solution presented herein decorrelates the quantization noise generated by the plurality of frequency programmable PLLs.

Embodiments described herein provide a system having phase synchronized local oscillator paths. The system includes a first circuit, which in turn includes a first counter configured to generate a first counter output signal in response to a first clock signal controlling the first counter. The first circuit also includes a first phase-locked loop coupled to the first counter. The first phase-locked loop is configured to receive the first counter output signal as a first synchronization clock for the first phase-locked loop and to generate a first output signal having rising edges aligned according to the first counter output signal.

The programmable frequency control system presented herein provides frequency programmability and phase noise reduction for signals generated by a plurality of frequency programmable phase-locked loops (PLLs). In general, a modulated data stream input to each of the plurality of PLLs controls the frequency of the signal output by the PLLs. The solution presented herein reduces the phase noise by introducing a time shift to the modulated data stream applied to at least some of the PLLs so that at least some of the PLLs receive time-shifted versions of the modulated data stream relative to other PLLs. In so doing, the solution presented herein decorrelates the quantization noise generated by the plurality of frequency programmable PLLs.

The digital delay-locked loop includes: a frequency divider, used to perform frequency division processing on a first clock-signal according to frequency division information, and output a second clock-signal; a signal-selector, used to select the first or second clock-signal as a third clock-signal according to the selection signal output; a delay line, used to delay the third clock-signal according to the delay control signal, and output a fourth clock-signal; a phase detector, used to receive the third and fourth clock-signals, perform phase detection processing, and output a phase detection judgment signal; and a state machine connected with the frequency divider, signal-selector, delay line and phase detector, used to adjust and control the frequency division information, the selection signal and the delay control signal output according to the phase detection judgment signal and a set state logic, to achieve that delay time of the fourth clock-signal relative to the first clock-signal.

The digital delay-locked loop includes: a frequency divider, used to perform frequency division processing on a first clock-signal according to frequency division information, and output a second clock-signal; a signal-selector, used to select the first or second clock-signal as a third clock-signal according to the selection signal output; a delay line, used to delay the third clock-signal according to the delay control signal, and output a fourth clock-signal; a phase detector, used to receive the third and fourth clock-signals, perform phase detection processing, and output a phase detection judgment signal; and a state machine connected with the frequency divider, signal-selector, delay line and phase detector, used to adjust and control the frequency division information, the selection signal and the delay control signal output according to the phase detection judgment signal and a set state logic, to achieve that delay time of the fourth clock-signal relative to the first clock-signal.

A high-frequency oscillator comprises a reference-frequency generator and a high-frequency generator. The reference-frequency generator generates a variable reference frequency and supplies it to the high-frequency generator. The high-frequency generator comprises a phase-locked loop and generates a high-frequency signal from the variable reference frequency. The phase-locked loop comprises at least one first mixer, a second mixer and several switches. The first mixer, the second mixer and the switches are connected in series. The mixers are connected into the phase-locked loop individually in a selective manner by means of the switches.

Frequency synthesizers having reduced phase noise and a small step size. One example can provide frequency synthesizers having low phase noise by eliminating dividers in a feedback path and instead employing frequency converters, such as mixers. Step size can be further reduced by providing frequency converters in a reference signal feedforward path. Acquisition time can be decreased by employing a fast-acquisition phase-locked loop that is switched out after acquisition in favor of a low phase-noise phase-locked loop. Another example can reduce phase noise by employing a YIG oscillator. To improve acquisition time, a first, faster phase-locked loop can be used to lock to a signal before switching to a second, slower phase-locked loop that includes the YIG oscillator. Another example can provide low noise by including phase-locked loops that operate in a frequency range having low thermal noise while a frequency of an output signal varies over a wide range.