A digital isolator comprising a set of bipolar transistors and an inductor capacitor (LC) oscillator coupled to the set of bipolar transistors in series, wherein the LC oscillator is configured to be turned on and off based on the current applied to the set of bipolar transistors or the LC oscillator and generate a set of differential signals based on the current flowing through the set of bipolar transistors and mimicking the operational characteristics of an optocoupler.

A drive level auto-tuning system includes a driver circuit, a resonant circuit, a driver controller and an automatic tuner. The resonant circuit is electrically connected to the driver circuit. The driver controller is electrically connected to the driver circuit. The automatic tuner is electrically connected to the driver controller, and the automatic tuner is configured to acquire a root-mean-square (RMS) current measured from the resonant circuit, so as to command the driver controller to automatically adjust a gain of driver circuit.

An oscillator includes: an external terminal, a resonator, and an oscillation circuit that oscillates the resonator, in which the oscillation circuit includes an amplification circuit and a current source which supplies a current to the amplification circuit, in which the current is set according to a first control signal which is input from the external terminal and a drive level of the resonator is changed according to the setting of the current.

A voltage controlled oscillator (VCO), a method of designing a voltage controlled oscillator, and a design structure comprising a semiconductor substrate including a voltage controlled oscillator are disclosed. In one embodiment, the VCO comprises an LC tank circuit for generating an oscillator output at an oscillator frequency, and an oscillator core including cross-coupled semiconductor devices to provide feedback to the tank circuit. The VCO further comprises a supply node, a tail node, and a noise by-pass circuit connected to the supply and tail nodes, in parallel with the tank circuit and the oscillator core. The by-pass circuit forms a low-impedance path at a frequency approximately twice the oscillator frequency to at least partially immunize the oscillator core from external noise and to reduce noise contribution from the cross-coupled semiconductor devices.

A clock signal is generated with an oscillator. A crystal oscillator core within the oscillator circuit is switched on to produce first and second oscillation signals that are approximately opposite in phase. When a difference between a voltage of the first oscillation signal and a voltage of the second oscillation signal exceeds an upper threshold range, the crystal oscillator core is switched off. When the difference between the voltage of the first oscillation signal and the voltage of the second oscillation signal falls below the upper threshold range, the crystal oscillator core is switched back on. This operation is repeated so as to produce the clock signal.

A crystal oscillator circuit that can be controlled for fast start-up and for efficient operation is disclosed. The control includes adjusting a voltage applied to a body terminal of a transistor in order to control the amplification of the crystal oscillator. The amplification can be increased, relative to a motional resistance of the crystal oscillator, at start-up to reduce a start-up time necessary for oscillation. The amplification can also be decreased in order to maintain oscillation after start-up more efficiently. In some implementations, the transistor for control is a fully depleted silicon on insulator (FDSOI) transistor that accommodates a wide range of body bias voltages.

A current control device for a differential circuit is provided. The current control device includes a differential circuit that generates differential signals comprising a positive signal and a negative signal in opposite phases, an amplitude detection circuit detecting an amplitude of the differential signal and outputting first and second detection voltages, an error amplification circuit controlling the differential circuit on the basis of an error voltage between the first and second detection voltages, and a current control circuit controlling the amplitude detection circuit on the basis of any one of the first and second detection voltages.

A self-biased amplifier includes a capacitor, a bias generation circuit and a common source amplifier. The capacitor is used to receive an input voltage and output an alternating component of the input voltage. The bias generation circuit is coupled to the capacitor, and used to generate a first bias voltage according to the alternating component. The common source amplifier is coupled to the bias generation circuit, and used to generate an amplified voltage according to the first bias voltage.

An oscillator start-up circuit and methodology for oscillator start-up is disclosed. The circuit includes a reference bias switch coupled to a reference node and a load node of a transconductor of an oscillator. The reference bias switch is responsive to a control signal for start-up of the oscillator and operable to close at a first time prior to start-up of the oscillator to maintain a voltage at the reference node equal to a voltage at the load node prior to application of bias to the transconductor. The reference bias switch is further operable to open at a second time subsequent to the first time. In one embodiment, a separate reference bias voltage is applied to a reference node of the transconductor.

An output buffer for an oscillator circuit and associated methodology. The output buffer has inverters and at least one negative feedback loop coupled to corresponding inverters. The negative feedback loop of the circuit is disabled in response to a control signal until one or more of a defined level of oscillation and a defined period of time is reached during start-up of the oscillator circuit, and is thereafter enabled. At least one of the inverters has at least one second negative feedback loop coupled to the corresponding inverter. An amount of feedback provided by the second negative feedback loop is adjustable in response to a control signal, where a first feedback level is present until a defined level of oscillation and/or a defined period of time is reached during start-up, a second feedback level is thereafter present in, and the first feedback level is less than the second feedback level.