Abstract: A frequency modulated output of a Digital Locked Loop (DLL) is implemented with a Johnson Counter outputting a sample clock and a synchronized digital code at a multiple of the sample clock. The digital code drives a digital-to-analog converter to generate a frequency modulated control signal. The control signal is summed with the center frequency control from the digital locked loop digital filter to provide a frequency modulated center frequency control signal to the DLL oscillator.

Abstract: An oscillator having improved frequency stability which includes an oscillator circuit and an SC-cut resonator connected with the oscillator circuit. The SC-cut resonator has a first turning point. A temperature compensation circuit is connected with the oscillator circuit. The temperature compensation circuit is adapted to adjust a reference frequency generated by the oscillator circuit according to a frequency response associated with a second turning point of an AT-cut resonator.

Abstract: An oscillation circuit used in a semiconductor device such as a cell-based IC, and comprises: an inverting amplifier, which is constructed so that it is possible connect a crystal oscillator XL between its input and output terminals, and so that it is possible to adjust its gain by a control signal CNT; and a wave-shaping circuit such as a Schmitt circuit that shapes the waveform of the oscillation signal output from the inverting amplifier. The wave-shaping circuit is constructed so that it is possible to adjust the gain when shaping a waveform according to a control signal CNT to correspond with the gain adjustment of the inverting amplifier.

Abstract: A constant temperature oscillator includes a crystal oscillator that is provided upright on a circuit board, an oscillation element arranged on the circuit board and configuring an oscillation circuit in conjunction with the crystal oscillator, and a temperature control element including a heating chip resistance and a thermistor, arranged on the circuit board, and configuring a temperature control circuit that keeps an operating temperature of the crystal oscillator constant, and which is provided with a heat transfer plate between the heating chip resistance and the bottom face of the oscillator container, wherein, the heat transfer plate has a notch into which the heating chip resistance is fitted, and a heat sink lies between the heat transfer plate and the heating chip resistance and closely contacts with them.

Abstract: A phase lock loop (PLL) frequency synthesizer includes a reconfigurable voltage controlled oscillator (VCO) with three modes of operation: a Linear-High-gain, Zero-gain, and Low-gain mode. During the linear high gain mode, the VCO enables an analogue self-calibration of the PLL over a wide frequency tuning range. Control voltage at the input of the VCO is varied by the PLL to provide an output frequency. When the PLL is locked, the VCO is switched to the Zero-gain mode while maintaining the output.

Abstract: According to an example embodiment, there is a testing device for testing a phase locked loop having a power supply input. The testing device comprises a power supply unit for providing a power supply signal VDD having a variation profile to the power supply input of the phase locked loop, wherein a width and height of said variation profile are formed in such a way, that the voltage controlled oscillator is prevented from outputting an oscillating output signal. There is a means for disabling a feedback signal to a phase comparator of the phase locked loop such that said phase locked loop is operated in an open loop mode, and a meter for measuring a measurement signal of the phase locked loop, while said power supply signal is provided to the power supply input.

Abstract: A plurality of variable load capacitance circuits is connected to each node between adjacent delay circuits of a ring oscillator, and changes load capacitance according to an external control signal. The control circuit adjusts timing the control signal is inputted to these variable load capacitance circuits, using a clock signal of one or more nodes of the ring oscillator.

Abstract: A radar oscillator has an oscillation unit and first and second switch circuits. The first switch circuit turns off an electric power supply to an amplifier in a non-input period of a pulse signal to set the oscillation unit in a non-oscillation state and turns on the electric power supply to the amplifier in an input period of the pulse signal to set the oscillation unit in an oscillation state. The second switch circuit turns on an electric power supply to an LC resonator in a period immediately before the pulse signal is input in a period in which the pulse signal is not input to supply a current to the LC resonator and turns off the electric power supply to the LC resonator at a timing at which the pulse signal is input, so that activation of an oscillation operation of the oscillation unit is accelerated.

Abstract: An oscillator is provided having an oscillator circuit including at least one oscillator circuit inductor and a first oscillator circuit capacitor, whereby the value of the first oscillator circuit capacitor is reversible by means of the first control voltages between different stages. The oscillator is characterized by a first control voltage source, which applies first control voltages with at least three stepwise different values to the first oscillator circuit capacitor. Preferably, the control voltages are generated over a network of current sources and resistors, whereby the network compensates for the thermal response of the oscillator. Further, a method for operating this type of oscillator is presented.

Abstract: A VCO circuit includes: a control portion to which a first voltage is inputted and from which a second voltage corresponding to the first voltage is outputted; a current source portion to which the second voltage is inputted and from which a current corresponding to the second voltage is outputted; and an oscillator circuit to which the current is inputted and from which a signal with a frequency in accordance with the current is outputted. The control portion includes an adjusting circuit which changes the second voltage in conjunction with fluctuation of a power supply voltage. Accordingly, fluctuation of the frequency Fo of an output signal of the VCO circuit can be suppressed even when the power supply voltage of the VCO circuit fluctuates.

Abstract: The invention is directed to a resonant circuit having a frequency-determining element which has at least one switchable frequency-changing element connected in parallel therewith. The frequency-changing element has two series-connected transistors whose control connections are connected to a node that receives a fixed potential. First connections of the two series-connected transistors are connected to one another and also to a control input for a control signal for switching the frequency-changing element of the resonant circuit. The invention keeps the control voltage for the two transistors at a higher potential than the threshold voltage for the transistors. This reduces a parasitic capacitance in the two transistors during operation.

Abstract: A feedback system such as a phase locked loop (PLL) includes a second feedback loop which responds when a VCO control voltage is near either end of its range, by slowly adjusting additional tuning elements which control the VCO frequency. The second feedback loop is arranged to cause a slow enough change in the VCO frequency that the first traditional feedback loop adjusts the control voltage quickly enough in a direction toward its mid-range value to keep the VCO frequency substantially unchanged. The second feedback loop advantageously incorporates one or more digital control signals which preferably change no more than one bit at a time and with a controlled slow ramp rate. As a result, the PLL maintains phase accuracy so that the operation of the PLL, including subtle specifications such as input data jitter tolerance or output jitter generation when used for clock and data recovery applications, is not negatively impacted.

Abstract: Disclosed is a push-push voltage controlled oscillator which obtains output signals having a frequency two times the fundamental resonance frequency of an LC resonator with differential signals having the same amplitude and opposite phases, creating the advantage of high frequency differential outputs which are obtained using such a voltage controlled oscillator, and thus reducing current consumption.

Abstract: The invention provides a method and apparatus to optimally estimate and adaptively compensate the temperature-induced frequency drift of a crystal oscillator in a navigational signal receiver. A Read-Write memory encodes two tables, one for looking up frequency drift values versus temperature readings and another one for valid data confirmation on the first table. The initially empty look-up table is gradually populated with frequency drift values while the receiver computes the frequency drift along with its position. During initial start of the receiver or re-acquisition of satellite signals, the stored frequency drift value corresponding to the current temperature is used. If no valid frequency drift value is available, the frequency drift value is computed based on the existing frequency drift values in the table. This invention reduces the Time-To-First-Fix (TTFF) of the receiver and enables the receiver to self-calibrate, thus no additional factory calibration would be necessary.

Abstract: A frequency fine tuning circuit for use in a voltage-controlled oscillator is provided. The frequency tuning circuit includes a first varactor, a second varactor and a center bias unit. The second varactor is coupled to the first varactor at a first node. The center bias unit maintains a node voltage of the first node at a constant bias voltage level.

Abstract: An oscillator comprises a data storage unit, an oscillation unit, and a control unit. The data storage unit is adapted to store a plurality of reference condition codes and a plurality of reference control codes. The oscillation unit is adapted to output an oscillation signal having an oscillation frequency that varies according to a control code. The control unit is adapted to generate the control code with a target value based on the reference condition codes and the reference control codes and a current condition code input to the control unit. Where control code has the target value, the oscillation unit outputs the oscillation signal with the oscillation frequency substantially equal to a target oscillation frequency.

Abstract: A detection device for detecting an oscillator is provided. The detection device includes an oscillator control circuit, a frequency-decreasing circuit and a display circuit. The oscillator control circuit is used for outputting the oscillator signal of the oscillator. The frequency-decreasing circuit is connected to the output of the oscillator control circuit and has a capacitor suitable for charging and discharging and a resistor, which can adjust the time constant of the oscillator signal. The display circuit is connected to the frequency-decreasing circuit for showing the output signal of the frequency-decreasing circuit. The detection device can decide whether the oscillator is normal or broken by observing a component of the display circuit, for example, the twinkling of a light emitting diode of the display circuit.

Abstract: A calibration circuit for voltage-controlled oscillator (VCO) includes a calibration bias generator, a VCO, a detection unit, a micro control unit, an adjuster unit, a phase-locked loop (PLL) unit, a control voltage detection unit, and a control switch set. The calibration bias generator outputs a first control voltage. The VCO outputs an oscillation frequency according to the first control voltage. The detection unit detects the oscillation frequency and outputs the detection result signal to the micro control unit. The micro control unit outputs an adjust signal according to the detection result signal. The adjuster unit receives the adjust signal voltage and adjusts the oscillation frequency output from the VCO according to the adjust signal voltage. The PLL unit outputs a second control voltage to the VCO. The control voltage detection unit outputs voltage-detection signal to the micro control unit, which outputs the adjust signal according to the voltage-detection signal.

Abstract: A circuit can include an oscillator core that outputs, in response to a bias signal, a periodic signal having an oscillation frequency; a bias circuit that, when powered, provides the bias signal (e.g., a voltage) to the oscillator core; and a switching circuit that periodically powers the bias circuit at a second frequency and provides the bias signal to the oscillator core when the bias circuit is not powered. The switching circuit can include a storage element that stores energy when the bias circuit is powered and uses stored energy to provide the bias signal when the bias circuit is not powered. The switching circuit can include a divider circuit that divides the oscillation frequency of the periodic signal to generate a control signal having the second frequency, and the bias circuit can be periodically powered at the second frequency in response to the control signal.

Abstract: A multimode-based phase modulating apparatus capable of reducing the degradation of modulation precision and suppressing the unnecessary power consumption. This apparatus has a switch for switching the modulation modes of a PLL circuit between a single-point modulation and a double-point modulation. In a case of a narrow modulation bandwidth, the switch is turned off to cease a second digital baseband signal, thereby causing the PLL circuit to perform the single-point modulation in which only a first digital baseband signal from a frequency division rate generating part is used for the modulation. Contrarily, in a case of a wide modulation bandwidth, the switch is turned on, thereby performing the double-point modulation using both the first digital baseband signal and the second digital baseband signal.