A quadrature oscillator according to the embodiments herein comprising two pairs of main transistors, two pairs of resonators and two pairs of injection transistors. The quadrature oscillator is split into two halves, which are separated in the chip layout. That is the two pairs of resonators are separated from each other, and the two pairs of the main transistors are separated from the resonator they coupled to such that the quadrature oscillator is separated into two spaced apart oscillator halves connected by transmission lines.

A system includes a voltage controlled oscillator (VCO) having an adjustable amplitude. The amplitude of the VCO may be adjusted by adjusting voltage level present at a center tap node of an inductor. The VCO may have an adjustable amplitude that may be programmed on a chip-by-chip basis based on a chip parameter, power consumption, or oscillator performance.

A circuit includes a coupling structure and a first inductive device. The coupling structure includes two or more conductive loops and a set of conductive paths electrically connecting the two or more conductive loops. The first inductive device is magnetically coupled with a first conductive loop of the two or more conductive loops.

A varainductor includes a spiral inductor, a ground ring, and a floating ring. The floating ring is disposed between the ground ring and the spiral inductor and surrounds a ring portion of the spiral inductor. A switching element, controlled by a switch control signal, selectively electrically connects the ground ring to the floating ring. The switching element includes one or more switches. The one or more switches are controlled by one or more signals of the switch control signal to adjust the inductance level of the varainductor.

Certain aspects of the present disclosure provide techniques and apparatus for generating multiple oscillating signals. One example circuit generally includes a first voltage-controlled oscillator (VCO) having a first inductor and a second VCO having a second inductor in parallel with a third inductor, wherein the second and third inductors are disposed inside a loop of the first inductor and may behave as a magnetic dipole. The loop of the first inductor may be symmetrical, and a combined geometry of loops of the second and third inductors may be symmetrical. The coupling coefficient (k) between the first inductor and a combination of the second and third inductors may be small (e.g., k<0.01), due to the symmetrical geometry of the circuit layout. With a smaller k, the first and second VCOs' inductors may be placed closer to one another, thereby reducing an area consumed by the two VCOs.

Certain aspects of the present disclosure provide techniques and apparatus for generating multiple oscillating signals. One example circuit generally includes a first voltage-controlled oscillator (VCO) having a first inductor and a second VCO having a second inductor in parallel with a third inductor, wherein the second and third inductors are disposed inside a loop of the first inductor and may behave as a magnetic dipole. The loop of the first inductor may be symmetrical, and a combined geometry of loops of the second and third inductors may be symmetrical. The coupling coefficient (k) between the first inductor and a combination of the second and third inductors may be small (e.g., k<0.01), due to the symmetrical geometry of the circuit layout. With a smaller k, the first and second VCOs' inductors may be placed closer to one another, thereby reducing an area consumed by the two VCOs.

In accordance with an embodiment, a voltage controlled oscillator (VCO) includes a VCO core having a plurality of transistors and a varactor circuit that has a first end coupled to emitter terminals of the VCO core and a second end coupled to a tuning terminal. The varactor circuit includes a capacitance that increases with increasing voltage applied to the tuning terminal with respect to the emitter terminals of the VCO core.

A Voltage-Controlled Oscillator (VCO) includes a cross-coupled transconductance cell. A transformer comprising a primary coil and at least one secondary coil, wherein the primary coil is connected to the cross-coupled transconductance cell. A primary coil varactor is connected to the cross-coupled transconductance cell in parallel to the primary coil. A variable inductive tuning component connected to the at least one secondary coil. A mode switch connected to the at least one secondary coil and configured to select a frequency mode of operation of the VCO by engaging or disengaging the variable inductive tuning component from operation with the primary coil varactor to generate oscillation at a center frequency of the VCO.

A voltage controlled oscillator that includes a first drive transistor including a first gate terminal connected to a first output node, the first drive transistor being connected between a second output node and a ground node; a second drive transistor connected between the first output node and the ground node, the second drive transistor including a second gate terminal connected to the second output node; a first inductor connected between the first output node and the second output node; and a second inductor and a first variable capacitance circuit connected in parallel between a first coupling node and a second coupling node. The second inductor receives a control voltage and is inductively coupled to the first inductor.

A quadrature oscillator according to the embodiments herein comprising two pairs of main transistors, two pairs of resonators and two pairs of injection transistors. The quadrature oscillator is split into two halves, which are separated in the chip layout. That is the two pairs of resonators are separated from each other, and the two pairs of the main transistors are separated from the resonator they coupled to such that the quadrature oscillator is separated into two spaced apart oscillator halves connected by transmission lines.