International Business Machines Corporation

Xiaodong Wang

Tao Liang

Xudong Wang

Joshua C Park

Aria Eshraghi

An integrated circuit transformer. A substrate supporting multiple layers of materials of an integrated circuit is provided with a first metallization layer comprising a first set of turns of a primary winding of a transformer, and a second set of turns of a secondary winding of the transformer. A insulation layer is deposited over the first metallization layer, and a second metallization layer bearing a second set of turns of the primary winding, and an optional third set of turns of a second secondary winding. A via connection connects one end of the first set of turns of the primary winding to the second turns of the primary winding located on the second metallization layer. The result is a transformer structure where the primary winding is provided on multiple layers and each secondary winding is confined to a single layer.

Integrated circuit transformer for radio frequency applications

An oscillator for generating a fundamental frequency signal and harmonic signal to provide multiple radio frequency signals. First and second bipolar transistors are differentially connected, and have base and collector terminals cross-coupled. A pair of inductors serially connect the collectors of the transistors to one terminal of a d.c. power supply source. A current source connects to the other terminal of the d.c. power supply source and to the emitters of the differentially connected transistor. A tuning capacitor connected between collector terminals establishes a resonant frequency for the oscillator. Crosscoupling is affected at a level that produces harmonic signals which can be used along with a fundamental frequency signal in numerous radio telecommunications applications.

Dual frequency voltage controlled oscillator circuit

A bandgap circuit for producing a constant current having a controllable temperature coefficient. A current mirror supplies first and second substantially identical currents to first and second bipolar transistors. A first resistor is connected across the emitters of the bipolar transistors. A second resistor connects one to the bipolar emitters to a common terminal where the current source currents are recombined and supplied to a common terminal of a power supply. The band gap voltage produced at the common base connections of the bipolar transistors have a voltage temperature coefficient which is controlled by the values of the resistors. A current source is coupled to receive the bandgap voltage and produces a current having a temperature coefficient corresponding to the voltage temperature coefficient of the bandgap voltage.

Constant current source having a controlled temperature coefficient

A cross-coupled voltage controlled oscillator having reduced phase noise. A pair of bipolar transistors having common emitter connections are coupled to reduce that oscillation frequency which is determined from a tuning circuit connected across the collectors of transistors. First and second varactor diodes provide analog tuning of the circuit, and a digitally controlled capacitor provides for a selection of a band of frequencies to be tuned by the varactor diodes. A current source provides the current to the emitter connections of the bipolar transistors. Second harmonic signals generated at the emitter of the transistors are significantly suppressed by a tuned filtered trap connected to the common emitter connections. By reducing the second harmonic signals, the phase noise or the voltage controlled oscillator can be significantly improved.

Cross-coupled voltage controlled oscillator with improved phase noise performance

A bandgap reference voltage circuit having a bandgap start-up circuit for initiating operation of the bandgap reference voltage circuit, a bandgap core circuit for developing a bandgap reference voltage, and a bandgap output circuit for supplying a bandgap reference voltage. The bandgap start-up circuit is connected to a low impedance leg in the bandgap core circuit and the bandgap output circuit has a feedback circuit that is connected to a high impedance leg in the bandgap core circuit. The connection of the bandgap start-up circuit to the low impedance leg of the bandgap core circuit eliminates the possibility of metastable operation of the bandgap reference voltage circuit. This bandgap reference voltage circuit can be used in battery powered units having reduced supply voltages as low as, for example, 1.7V and the arrangement of the feedback circuit of the bandgap output circuit allows supplying of reference voltages greater and less than typical bandgap voltage.

Bandgap reference voltage circuit

A mixer for a wireless communications system having a differential amplifier that translates an input intermediate frequency voltage signal or an input radio frequency voltage signal to current signals that are supplied to a doubly-balanced switching modulator that develops a differential mixed output radio frequency signal or intermediate frequency signal that is the product of the current signals and a local oscillator signal. Included in the differential amplifier are a first reactance circuit and a second reactance circuit each of which provides a low impedance to ground at the second harmonic of the local oscillator signal and a high impedance at the frequency of the input radio frequency signal or input intermediate frequency signal.

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Acton, MA, United States of America

Xiaodong Wang