A capacitor circuit includes a capacitor array including first to n-th capacitors connected to each other in parallel; a select switch circuit including first to n-th select switches connected to the first to n-th capacitors in series, respectively; and a short switch circuit including first to n-th short switches connected to the first to n-th capacitors in parallel, respectively, and operating complementarily to the first to n-th select switches, respectively, wherein n is an integer of 2 or greater.

A variable capacitor circuit includes a capacitor block including a first varactor element comprising a first transistor having a first size, a second varactor element comprising a second transistor having a second size different from the first size, a first terminal commonly connected to a source and a drain of the first transistor, a second terminal commonly connected to a source and a drain of the second transistor, and an RC circuit connected to a gate of the first transistor and a gate of the second transistor.

The embodiments of the invention relate to a radio frequency oscillator, the radio frequency oscillator comprising a resonator circuit 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 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 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 frequency doubler (tripler, or quadrupler) employs current re-use coupled oscillator technique to enhance phase noise without increasing current consumption. Frequency doubler uses coupling between two oscillators running at different frequencies; a first oscillator is running at the target frequency and a second oscillator is running at half the frequency. The coupling between the two oscillators is via a transformer having a primary transformer coil and a secondary transformer coil. The first oscillator comprises a differential inductor, coarse/fine tuning capacitor arrays, and an n-type trans-conductor (GM). A virtual ground node of the n-type GM is coupled to one side of the primary transformer coil and the other side of the primary coil is coupled to the center tap of the secondary coil. The second oscillator comprises the secondary coil, coarse/fine tuning capacitor arrays, n-type GM, frequency tracking loop (FTL) and 2.sup.nd-harmonic LC filter network.

A semiconductor device according to the present embodiment includes a plurality of switching elements and a plurality of variable capacitance elements. The switching elements are switching elements connected in series between a first control terminal and a second control terminal and plural types of capacitance control signals can be supplied to the first control terminal and the second control terminal. The variable capacitance elements have capacitance control terminals connected to corresponding one ends of the switching elements, respectively.

An oscillator includes: a first inductor; and a programmable capacitor bank coupled between a first terminal of the first inductor and a second terminal of the first inductor, where the programmable capacitor bank includes a plurality of cells concatenated together, where each cell of the plurality of cells includes a first node, a second node, a third node, a second inductor, and a programmable capacitor, where the second inductor is coupled between the first node and the third node, and the programmable capacitor is coupled between the third node and the second node, where a first inductance of the first inductor is larger than a sum of the inductances of the second inductors of the programmable capacitor bank.

An electronic device may include a transceiver with mixer circuitry that up-converts or down-converts signals based on a voltage-controlled oscillator (VCO) signal. The transceiver circuitry may include first, second, third, and fourth VCOs. Each VCO may include a VCO core that receives a control voltage and an inductor coupled to the VCO core. Fixed linear capacitors may be coupled between the VCO cores. A switching network may be coupled between the VCOs. Control circuitry may place the VCO circuitry in one of four different operating modes and may switch between the operating modes to selectively control current direction in each of the inductors. The VCO circuitry may generate the VCO signal within a respective frequency range in each of the operating modes. The VCO circuitry may exhibit a relatively wide frequency range across all of the operating modes while introducing minimal phase noise to the system.

An element includes a coupling line in which a first conductor layer, a dielectric layer, and a second conductor layer are stacked in this order, and which is connected to the second conductor layer in order to mutually synchronize a plurality of antennas at a frequency of a terahertz wave; and a bias line connecting a power supply for supplying a bias signal to a semiconductor layer and the second conductor layer. A wiring layer in which the coupling line is formed and a wiring layer in which the bias line is formed are different layers. The bias line is disposed in a layer between the first conductor layer and the second conductor layer.

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 (VCO) circuitry includes a varactor array. The varactor array includes a first varactor unit including a first varactor, a second varactor, and first switch circuitry. The first varactor is connected to a first node and a second node, and the second varactor is connected to the second node and a third node. The second node receives a voltage control signal. The first switch circuitry is electrically coupled to the first node and the third node, and selectively electrically couples a first voltage signal to the first node and the third node based on a first control signal.