A frequency generation solution controls an oscillator amplitude using two feedback paths to generate high frequency signals with lower power consumption and lower noise. A first feedback path provides continuous control of the oscillator amplitude responsive to an amplitude detected at the oscillator output. A second feedback path provides discrete control of the amplitude regulating parameter(s) of the oscillator responsive to the detected oscillator amplitude. Because the second feedback path enables the adjustment of the amplitude regulating parameter(s), the second feedback path enables an amplifier in the first feedback path to operate at a reduced gain, and thus also at a reduced power and a reduced noise, without jeopardizing the performance of the oscillator.

Embodiments include apparatuses, methods, and systems for open-loop voltage regulation and drift compensation for a digitally controlled oscillator (DCO). In embodiments, a communication circuit may include a DCO, an open-loop voltage regulator, and a calibration circuit. The open-loop voltage regulator may receive a calibration voltage and may generate a regulated voltage. The regulated voltage may be passed to the DCO. During a calibration mode, the calibration circuit may compare the regulated voltage to a reference voltage and adjust the calibration voltage based on the comparison to provide the regulated voltage with a target value. During a monitoring mode, the calibration circuit may receive a tuning code that is used to tune the DCO and further adjust the calibration voltage based on a value of the tuning code.

Apparatus for communicating across an isolation barrier. In one embodiment, the apparatus comprises a transformer having a first winding disposed on a first side of a printed circuit board (PCB) and coupled to a first local ground, and a second winding disposed on a second side of the PCB, the second side opposite to the first side, and coupled to a second local ground; a transmitter coupled to the first winding; and a receiver, coupled the second winding, that generates an output signal based on a signal received from the transmitter.

A frequency generation solution controls an oscillator amplitude using two feedback paths to generate high frequency signals with lower power consumption and lower noise. A first feedback path provides continuous control of the oscillator amplitude responsive to an amplitude detected at the oscillator output. A second feedback path provides discrete control of the amplitude regulating parameter(s) of the oscillator responsive to the detected oscillator amplitude. Because the second feedback path enables the adjustment of the amplitude regulating parameter(s), the second feedback path enables an amplifier in the first feedback path to operate at a reduced gain, and thus also at a reduced power and a reduced noise, without jeopardizing the performance of the oscillator.

Systems and methods are provided in which a voltage-controlled oscillator for a radio transmitter includes a LC tank circuit, and a muting circuit. The LC tank circuit includes an inductive element and a capacitive element; wherein the inductive element of the LC tank circuit includes the antenna of the transmitter. The muting circuit can include a variable resistor connected in parallel with the LC tank circuit.

Provided is a method for controlling the bias current, I.sub.PIERCE, of an oscillator. The method includes acquiring or determining a digital representation encoding a bias current. The method also includes carrying out an algorithm to update the digital representation if the oscillation amplitude is measured, by one or more peak detectors, to be outside of upper and lower thresholds. Also provided is an apparatus arranged to control the bias current of an oscillator using this method, the apparatus including one or more peak detectors and a current digital to analogue converter.

A receiver front-end capable of receiving RF inputs having a broad range of levels. The receiver comprises a low-noise amplifier (LNA) operating in a variety of bias modes that cover a large gain range. Branches of the amplifier can be turned on in various combinations to allow selection of different bias modes. A degeneration inductor coupled to the source of the common source FET of each branch has a plurality of taps that are coupled to degeneration switches that can ground the tap to effectively shorten the degeneration inductor and reduce the amount of degeneration inductance. The degeneration inductor and associated switches can be fabricated using one of several physical layouts. Operating the degeneration switches to select the length of the degeneration inductor to match the bias mode reduces changes in the input impedance as different bias modes are selected.

A local oscillator device includes an oscillator module including a first inductive element and a capacitive element coupled in parallel with the inductive element. A frequency divider is coupled to the oscillator module for delivering a local oscillator signal. The local oscillator device includes an autotransformer including the first inductive element and two second inductive elements respectively coupled to the terminals of the first inductive element and to two output terminals of the autotransformer, the output terminals being further coupled to input terminals of the frequency divider.

A circuit may comprise a first node, a ring oscillator, a regulator, and a Kvcc compensation circuit. The first node may be a supply node to provide a supply voltage for the circuit. The ring oscillator may be formed from inverters. The regulator may use a single transistor between the first node and a second node for powering the oscillator. The K compensation circuit may be used to provide to the oscillator a variable capacitive load that is dependent on the supply at the first supply node, and it may drag oscillator frequency down when the first node supply goes up.

A voltage controlled oscillator (VCO) and a method of operating the VCO are disclosed. The VCO includes an inductor device, a capacitor device coupled in parallel with the inductor device through first and second nodes, and a pair of cross-coupled transistors coupled in parallel with the inductor device and the capacitor device through the first and second nodes. At least one of the pair of cross-coupled transistor includes a plurality of sub transistors coupled in parallel. The sub transistors are individually switchable to adjust current drive capability of each of the sub transistors. Each of the sub transistors includes a first gate and a second gate.