Transformer based voltage controlled oscillator circuitry for phase-locked loop circuitry includes upper band circuitry and lower band circuitry. The upper band circuitry operates in a first frequency range and includes a first capacitor array having a variable capacitance. The lower band circuitry operates in a second frequency range and includes a second capacitor array having a variable capacitance. The first frequency range higher than the second frequency range. In a first operating mode, the first capacitor array has a first capacitance value and the second capacitor array has a second capacitance value. In a second operating mode, the second capacitor array has a third capacitance value different than the second capacitance value.

A voltage-controlled oscillator device includes first and second voltage-controlled oscillators, a first switch group including two first switches, and a second switch group including two second switches. The first voltage-controlled oscillator includes a first inductor group, a first negative resistance circuit and a first voltage output terminal group. The second voltage-controlled oscillator includes a second inductor group, a second negative resistance circuit and a second voltage output terminal group. For the first switch group, first control terminals are electrically connected to the first voltage output terminal group, first input terminals are electrically connected to the second voltage output terminal group, first output terminals are electrically connected. For the second switch group, second control terminals are electrically connected to the second voltage output terminal group, second input terminals are electrically connected to the first voltage output terminal group, second output terminals are electrically connected.

A semiconductor device and a communication circuit capable of reducing the effect of a noise generated in an inductor are provided. A semiconductor device according to an embodiment includes a substrate, a first circuit disposed in a first area of the substrate, a second circuit disposed in a second area of the substrate, the second circuit being configured to operate selectively with the first circuit, a first inductor disposed in the second area and connected to the first circuit, and a second inductor disposed in the first area and connected to the second circuit.

Embodiments of the present disclosure may provide a circuit comprising a tank circuit. The tank circuit may include an inductor having a pair of terminals, a first pair of transistors, and a first pair of capacitors. Each transistor may be coupled between a respective terminal of the inductor and a reference voltage along a source-to-drain path of the transistor. Each capacitor may be provided in a signal path between an inductor terminal coupled to a respective first transistor in the first pair and a gate of a second transistor in the first pair.

A dual-band voltage controlled oscillator (VCO) includes: a first oscillator circuit including a first inductor; a second oscillator circuit including a second inductor; a first mode switch configured to electrically connect or disconnect a first output terminal of the first oscillator circuit and a first output terminal of the second oscillator circuit; a second mode switch configured to electrically connect or disconnect a second output terminal of the first oscillator circuit and a second output terminal of the second oscillator circuit; a third mode switch configured to electrically connect or disconnect a first terminal of the first inductor and a first terminal of the second inductor; and a fourth mode switch configured to electrically connect or disconnect a second terminal of the first inductor and a second terminal of the second inductor.

Systems and methods are provided for hopping a digitally controlled oscillator (DCO) among a plurality of channels, wherein a gain of the DCO K.sub.DCO is a nonlinear function of frequency. A first normalized tuning word (NTW) corresponding to a first channel of the plurality of channels is generated. A first normalizing gain multiplier X is generated based on the nonlinear function of frequency, on an estimate of the nonlinear function of frequency, at a first frequency corresponding to the first channel. The first NTW is multiplied by the first X to obtain a first oscillator tuning word (OTW). The first OTW is input to the DCO to cause the DCO to hop to the first channel. A system for hopping among a plurality of channels at a plurality of respective frequencies comprises a phase-locked loop (PLL), a digitally controlled oscillator (DCO), a multiplexer, and an arithmetic module.

A voltage-controlled oscillator device includes first and second voltage-controlled oscillators, a first switch group including two first switches, and a second switch group including two second switches. The first voltage-controlled oscillator includes a first inductor group, a first negative resistance circuit and a first voltage output terminal group. The second voltage-controlled oscillator includes a second inductor group, a second negative resistance circuit and a second voltage output terminal group. For the first switch group, first control terminals are electrically connected to the first voltage output terminal group, first input terminals are electrically connected to the second voltage output terminal group, first output terminals are electrically connected. For the second switch group, second control terminals are electrically connected to the second voltage output terminal group, second input terminals are electrically connected to the first voltage output terminal group, second output terminals are electrically connected.

Systems and methods are provided for hopping a digitally controlled oscillator (DCO) among a plurality of channels, wherein a gain of the DCO K.sub.DCO is a nonlinear function of frequency. A first normalized tuning word (NTW) corresponding to a first channel of the plurality of channels is generated. A first normalizing gain multiplier X is generated based on the nonlinear function of frequency, on an estimate of the nonlinear function of frequency, at a first frequency corresponding to the first channel. The first NTW is multiplied by the first X to obtain a first oscillator tuning word (OTW). The first OTW is input to the DCO to cause the DCO to hop to the first channel. A system for hopping among a plurality of channels at a plurality of respective frequencies comprises a phase-locked loop (PLL), a digitally controlled oscillator (DCO), a multiplexer, and an arithmetic module.

A reference frequency signal generator comprises a plurality of ovenized reference crystal oscillators (OCXOs) having different turn-over-temperatures, a selector logic circuit coupled to outputs of the OCXOs, a temperature sensor, and a controller coupled to an output of the temperature sensor. The selector logic circuit outputs one of the outputs of the OCXOs based on a control signal from the controller. The controller also generates control signals for the OCXOs. In some implementations, the reference frequency signal generator includes a phase-locked loop or a fractional output divider coupled to the output of the selector logic circuit and configured to receive a calibration signal from the controller.

Systems and methods are provided for hopping a digitally controlled oscillator (DCO) among a plurality of channels, wherein a gain of the DCO K.sub.DCO is a nonlinear function of frequency. A first normalized tuning word (NTW) corresponding to a first channel of the plurality of channels is generated. A first normalizing gain multiplier X is generated based on the nonlinear function of frequency, on an estimate of the nonlinear function of frequency, at a first frequency corresponding to the first channel. The first NTW is multiplied by the first X to obtain a first oscillator tuning word (OTW). The first OTW is input to the DCO to cause the DCO to hop to the first channel. A system for hopping among a plurality of channels at a plurality of respective frequencies comprises a phase-locked loop (PLL), a digitally controlled oscillator (DCO), a multiplexer, and an arithmetic module.