A voltage-controlled oscillator comprises a varactor. A capacitance of the first varactor is dependent upon a control voltage. The voltage-controlled also comprises an inductor. The inductor is connected to a center-tap connection. The voltage-controlled oscillator also comprises a power source. The power source is configured to provide a bias voltage to the inductor through the center-tap connection. The voltage-controlled oscillator also comprises a coupling capacitor. The coupling capacitor is located between the inductor and the varactor. The voltage-controlled oscillator also comprises a coupling resistor. The coupling resistor is located between the coupling capacitor and the center-tap connection. The center-tap connection provides the bias voltage to the coupling capacitor through the coupling resistor.

A voltage controlled oscillator includes a series resonant circuit having a resonance frequency and an active voltage driving device coupled to the series resonant circuit. The active voltage driving device provides a driving voltage and has an output negative resistance in an operative voltage range at the resonance frequency. The active voltage driving device includes a cross-coupled differential pair having voltage supply terminals providing the driving voltage. The series resonant circuit is coupled between the voltage supply terminals of the cross-coupled differential pair.

Power isolators for providing electrical isolation between an input port and an output port that exhibit low electromagnetic interference (EMI) are described. The low EMI may be achieved by, for example, canceling out a common mode current across a transformer in the power isolator that may be converted into EMI. The power isolator may include at least one oscillator circuit that is configured to apply a first signal to a first transformer and a second, different signal to a second transformer. The first and second signals may be configured such that the common mode current generated in each of the first and second transformers has an opposite direction. Thus, the common mode currents in the first and second transformers may at least partially cancel out. As a result, the EMI exhibited by the power isolator may be reduced.

An apparatus includes a digitally controlled oscillator (DCO), which includes an inductor coupled in series with a first capacitor. The DCO further includes a second capacitor coupled in parallel with the series-coupled inductor and first capacitor, a first inverter coupled in parallel with the second capacitor, and a second inverter coupled back-to-back to the first inverter. The DCO further includes a digital-to-analog-converter (DAC) to vary a capacitance of the first capacitor.

The disclosure relates to technology for power supply for a voltage controller oscillator (VCO). A peak detector circuit determines the amplitude of the output for the VCO, which is compared to a reference value in an automatic gain control loop. An input voltage for the VCO is determined based on a difference between the reference value and the output of the peak detector circuit. The peak detector circuit can be implemented using parasitic bipolar devices in an integrated circuit formed in a CMOS process.

In an example, a system includes an oscillator circuit on a chip. The oscillator circuit includes a charging current generator including a current mirror and an amplifier, where the amplifier is coupled to a pin on the chip, and where the pin is adapted to be coupled to an external resistor, where the external resistor is external to the chip. The oscillator circuit also includes oscillator circuitry coupled to the charging current generator, where the oscillator circuitry includes a comparator, a phase generator, a first capacitor coupled to a first switch, and a second capacitor coupled to a second switch. The oscillator circuit includes leakage circuitry coupled to the current mirror, where the leakage circuitry is configured to draw a current from the current mirror proportional to a leakage current flowing through the external resistor from circuitry internal to the chip.

Embodiments herein describe a self-biased divider for a clock in an integrated circuit. In one embodiment, the clock includes a VCO that generates a clock signal that is output to the self-biased divider. However, because the VCO may generate an analog clocking signal (e.g., a low amplitude sine wave of unknown common mode) to reduce jitter, the amplitude can vary which means it may not sufficiently track CMOS parameters. The clocking signals generated by the self-biased divider are used as feedback signals for DC biasing (or DC leveling). In this manner, the divider is referred to a self-biased divider since signals generated by the divider are used to perform DC biasing/leveling.

The multi-modal imaging system, in particular for brain imaging, comprising a pump signal generator which emits at least one pump signal in the radio frequency (RF)-range with a first power P1 and a second power P2, a wireless detection unit, which comprises at least one parametric resonator circuit with multiple resonance modes, wherein the at least one parametric resonator circuit comprises at least two varactors, at least one capacitor and at least one inductance, wherein, in a first detection mode, the pump signal, having a first power P1, induces a first pump current in the at least one parametric resonator circuit, wherein the at least one parametric resonator circuit is operated below its oscillation threshold and generates a first output signal by amplifying a first input signal, which is provided due to a magnetic-resonance (MR) measurement, wherein an external receiving device receives the first output signal, wherein, in a second detection mode, the pump signal, having a second power P2, induces a second pump current in the at least one parametric resonator circuit, wherein the at least one parametric resonator circuit is operated above its oscillation threshold and generates a second output signal, wherein the second output signal is modulated with a second input signal, wherein the second input signal is provided by at least one neuronal probe device, connected to the at least one parametric resonator circuit, wherein the external receiving device receives the second output signal.

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.

According to an aspect, a tank circuit in an integrated circuit comprising a plurality of metal strips forming a first part of a closed contour enclosing a first area, a set of split sections forming a second part and geometrically aligned with the closed contour, and a plurality of capacitors coupled between the split sections to form the tank circuit, wherein a first flux linkage due a current flowing in the set of split sections pass through the first area in the same direction as that of a second flux linkage due to the current flowing in the plurality of metal strips, and the set of split sections and the plurality of metal strips together forming an inductance coil.