The invention relates to a resonator circuit, the resonator circuit comprising a transformer comprising a primary winding and a secondary winding, wherein the primary winding is inductively coupled with the secondary winding, a primary capacitor being connected to the primary winding, the primary capacitor and the primary winding forming a primary circuit, and a secondary capacitor being connected to the secondary winding, the secondary capacitor and the secondary winding forming a secondary circuit, wherein the resonator circuit has a common mode resonance frequency at an excitation of the primary circuit in a common mode, wherein the resonator circuit has a differential mode resonance frequency at an excitation of the primary circuit in a differential mode, and wherein the common mode resonance frequency is different from the differential mode resonance frequency.

A voltage controlled oscillator (VCO) and buffer circuit includes a voltage controlled oscillator (VCO), a buffer circuit configured to receive a signal generated by the VCO, the buffer circuit comprising a first transistor having a parasitic gate-source capacitance (Cgs), and a second transistor coupled across the first transistor, wherein a gate of the first transistor is coupled to a drain and a source of the second transistor, and a gate of the second transistor is coupled to a source of the first transistor.

An oscillator includes a tunable resonant circuit having an inductance and a variable capacitance coupled between first and second nodes, and a set of capacitances selectively coupleable between the first and second nodes. An input control node receiving an input control signal is coupled to the variable capacitance and set of capacitances. The tunable resonant circuit is tunable based on the input control signal. A biasing circuit biases the tunable resonant circuit to generate a variable-frequency output signal between the first and second nodes. A voltage divider generates a set of different voltage thresholds, and a set of comparator circuits with hysteresis compares the input control signal to the set of different voltage thresholds to generate a set of control signals. The capacitances in the set of capacitances are selectively coupleable between the first and second nodes as a function of control signals in the set of control signals.

Circuits and processes for locking a voltage-controlled oscillator (VCO) at a high frequency signal are described. A circuit may include an adjustable current converter (ACC), coupled at an input terminal to a power source, operable to output a control signal (VC) at an output terminal. A first switch may be coupled to the ACC and to the VCO. The VCO, when in an “ON” state, receives the control signal and outputs a high frequency signal (VHF). A digital filter may be coupled to the VCO and operable to receive the VHF. Based on the VHF, the digital filter generates a data signal having a data value. The circuit may also include a digital-to-analog converter (DAC) operable to receive the data signal and, based on the data value, output an adjustment signal to the ACC. The ACC may adjust the control signal based on the adjustment signal received from the DAC.

Devices, systems, and methods for locking a voltage controlled oscillator (VCO) at a high frequency may include use of a VCO and an integrator, which generates and outputs a control signal to the VCO, based on an inverting signal and a reference signal. The control signal locks the VCO to a high frequency signal (FH). A frequency divider is coupled to the VCO, receives FH from the VCO, divides FH by a factor “F”, and outputs a low frequency signal (FL). A switched capacitor resistor circuit (SCRC) is coupled to the frequency divider and the integrator. The SCRC receives FL from the frequency divider and generates the inverting signal. An integrating capacitor is coupled across an inverting and an output terminal of op-amp in the integrator. The output of the op-amp provides an integrator signal, which may be (optionally) filtered to produce the control signal.

The disclosure relates to a radio frequency oscillator, the radio frequency oscillator comprising a resonator circuit being resonant at an excitation of the resonator circuit in a differential mode and at an excitation of the resonator circuit in a common mode, wherein the resonator circuit has a differential mode resonance frequency at the excitation in the differential mode, and wherein the resonator circuit has a common mode resonance frequency at the excitation in the common mode, a first excitation circuit being configured to excite the resonator circuit in the differential mode to obtain a differential mode oscillator signal oscillating at the differential mode resonance frequency, and a second excitation circuit being configured to excite the resonator circuit in the common mode to obtain a common mode oscillator signal oscillating at the common mode resonance frequency.

A voltage controlled oscillator (VCO) circuit employing digital amplitude control of the output oscillating signal and method of operation. The digital control is provided by an analog to digital converter (ADC) element that is shared among many other operating blocks in a system. In a configuration, the oscillator current is obtained by implementing transistors in a linear region and controlling them digitally. The optimum amplitude detection is performed by measuring the DC voltage at the common mode nodes in the oscillator, and is realized using reduced time compared to an extensive frequency measurement over a long time window. The digital control is implemented using an on-chip regulator, and employs digital controls for adjusting the current consumption which leads to low on-chip area overhead, low cost, and a scalable implementation. In an implementation, a one-time code can be obtained for optimum phase noise operation when providing the digital amplitude control.

The invention relates to a resonator circuit, the resonator circuit comprising a transformer comprising a primary winding and a secondary winding, wherein the primary winding is inductively coupled with the secondary winding, a primary capacitor being connected to the primary winding, the primary capacitor and the primary winding forming a primary circuit, and a secondary capacitor being connected to the secondary winding, the secondary capacitor and the secondary winding forming a secondary circuit, wherein the resonator circuit has a common mode resonance frequency at an excitation of the primary circuit in a common mode, wherein the resonator circuit has a differential mode resonance frequency at an excitation of the primary circuit in a differential mode, and wherein the common mode resonance frequency is different from the differential mode resonance frequency.

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 voltage controlled oscillator (VCO) circuit employing digital amplitude control of the output oscillating signal and method of operation. The digital control is provided by an analog to digital converter (ADC) element that is shared among many other operating blocks in a system. In a configuration, the oscillator current is obtained by implementing transistors in a linear region and controlling them digitally. The optimum amplitude detection is performed by measuring the DC voltage at the common mode nodes in the oscillator, and is realized using reduced time compared to an extensive frequency measurement over a long time window. The digital control is implemented using an on-chip regulator, and employs digital controls for adjusting the current consumption which leads to low on-chip area overhead, low cost, and a scalable implementation. In an implementation, a one-time code can be obtained for optimum phase noise operation when providing the digital amplitude control.