An oscillator includes a forward stage including first and second terminals and a transformer-coupled band-pass filter (BPF) coupled between the first and second terminals and including a coupling device between the first and second terminals, and a transformer including first and second windings in a metal layer of an IC. The first winding includes a first conductive structure coupled to the first terminal and a second conductive structure coupled to a voltage node, a third conductive structure including first and second extending portions connected to the first and second conductive structures. The second winding includes a fourth conductive structure including a third extending portion coupled to the voltage node, and a fourth extending portion coupled to the second terminal. The third extending portion is between the second conductive structure and the first extending portion, and the fourth extending portion is between the first conductive structure and the second extending portion.

An oscillator circuit includes an oscillator transistor (Q1) having respective first, second, and control terminals, the oscillator transistor being arranged to generate a microwave oscillating signal at the first terminal. A surface integrated waveguide resonator (Y1) is connected to the second terminal of the oscillator transistor (Q1). An active bias circuit portion (202) including a negative feedback arrangement is between the first terminal of the oscillator transistor (Q1) and the control terminal of the oscillator transistor (Q1), the active bias circuit portion being arranged to supply a bias current to the control terminal of the oscillator transistor (Q1). The bias current is dependent on a voltage at the first terminal of the oscillator transistor (Q1) multiplied by a negative gain.

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.

A radiofrequency transmission/reception integrated circuit includes at least one radiofrequency signal amplifier (PA, LNA), the at least one amplifier being configured, in operational mode, so as to perform a function of amplifying a radiofrequency signal applied at input, wherein the amplifier is configured so as to perform an oscillator function in a self-test mode of the integrated circuit, to generate a radiofrequency signal on at least one of the input or the output of said amplifier. A self-test method for such an integrated circuit is also provided.

A band-pass filter (BPF) includes first and second windings. The first winding includes first and second terminals, a first outer extending portion extending from the first terminal, a second outer extending portion extending from the second terminal, and a first conductive structure configured to electrically connect the first and second outer extending portions to each other at a location opposite the first and second terminals. The second winding includes third and fourth terminals positioned between the first and second terminals, and a second conductive structure electrically connected to the third and fourth terminals and extending between the first conductive structure and each of the first and second outer extending portions.

An oscillator includes a forward stage including first and second terminals and a transformer-coupled band-pass filter (BPF) coupled between the first and second terminals and including a coupling device between the first and second terminals, and a transformer including first and second windings in a metal layer of an IC. The first winding includes a first conductive structure coupled to the first terminal and a second conductive structure coupled to a voltage node, a third conductive structure including first and second extending portions connected to the first and second conductive structures. The second winding includes a fourth conductive structure including a third extending portion coupled to the voltage node, and a fourth extending portion coupled to the second terminal. The third extending portion is between the second conductive structure and the first extending portion, and the fourth extending portion is between the first conductive structure and the second extending portion.

A differential oscillator includes a differential circuit and a transformer-coupled band-pass filter (BPF) coupled between first and second output nodes. The BPF includes a coupling device coupled between the output nodes and a transformer including first and second windings in a metal layer of an IC. The first winding includes first and second conductive structures coupled to the first output node and a voltage node, respectively, and a third conductive structure including first and second extending portions connected to the first and second conductive structures, respectively. The second winding includes a fourth conductive structure including a third extending portion coupled to the voltage node and a fourth extending portion coupled to the second output node. The third extending portion is between the second conductive structure and the first extending portion, and the fourth extending portion is between the first conductive structure and the second extending portion.

A two-wire displacement sensor device includes an LC oscillation circuit including a coil whose inductance changes in accordance with a displacement amount of an object and an oscillation unit provided with capacitors and amplifying elements; and an interface unit serving as a signal output unit and a power supply input unit. The interface unit includes a constant current circuit that outputs at least two current values.

In some embodiments, a differential oscillator includes a differential circuit coupled between a first output node and a second output node and a transformer-coupled band-pass filter (BPF). The transformer-coupled BPF is coupled between the first output node and the second output node and includes a coupling device and a transformer. The coupling device is coupled between the first output node and the second output node. The transformer includes a first winding coupled between the first output node and a voltage node and a second winding coupled between the second output node and the voltage node.

A resonance oscillator circuit is provided to include first and second oscillators. The first oscillator includes a first LC resonator circuit and an amplifier element, and oscillates by shifting a phase of an output voltage with a predetermined phase difference and feeding the output voltage back to the amplifier element. The second oscillator oscillates by generating a gate signal, which has a frequency identical to that of the output voltage, and drives the amplifier element, by shifting the phase of the output voltage with the phase difference and feeding the gate signal back to an input terminal of the amplifier element, by using the amplifier element as a switching element and using the first oscillator as a feedback circuit. The phase difference is a value substantially independent of an inductance of the first LC resonator circuit and a load, to which the output voltage is applied.