Hittite Microwave Corporation

Analog Devices,inc.

Cemin Zhang

Michael Koechlin

John A Chiesa

Ekrem Oran

John Poelker

Christopher Thomas Lyons

Byungmoo Min

Christopher O'Neill

Aspects of this disclosure relate to a first die includes an LC resonant circuit including a first capacitive element, such as a capacitor or a varactor, and an inductive element. The LC resonant circuit is configured to generate a signal having a frequency of oscillation. The first die includes bump pads electrically coupled to both ends of the first capacitive element. A second die can be flip chip mounted on the first die. Bumps can electrically connect a second capacitive element of the second die in parallel with the first capacitive element of the first die. This can increase the Q factor of the LC resonant circuit.

Resonant circuit including bump pads

Apparatus and methods for multi-mode low noise amplifiers (LNAs) are provided herein. In certain configurations, a radio frequency (RF) system includes a multi-mode LNA including at least a first amplification stage and a second amplification stage electrically connected in a cascade. The RF system further includes a mode control circuit, which receives a mode selection signal and controls the biasing of the first and second amplification stages based on the mode selection signal. The mode control circuit operates the multi-mode LNA in one of a plurality of modes including both a first mode in which the LNA operates with higher gain and better noise figure and a second mode in which the LNA operates with lower gain and higher linearity. Controlling the mode of the multi-mode LNA using the mode selection signal allows the multi-mode LNA to advantageously achieve both the benefits of low noise figure and high linearity.

Apparatus and methods for multi-mode low noise amplifiers

A die is packaged by flip-chip mounting the die with the active side facing a low loss substrate. A ground plane is coupled to the active side of the die by vias through the low loss substrate. The ground plane is positioned to concentrate high frequency electromagnetic fields in the low loss substrate. A tuning height can be adjusted to tune the center frequency of a circuit in the die.

Circuit with reduced noise and controlled frequency

This invention features an absorptive tunable bandstop filter with a wide tuning range including first and second branches of all-pass filter networks, an input power divider for splitting the input signal and passing approximately half of the input signal power through each branch of the all-pass filter networks, and an output power combiner for recombining the signal power from each branch of the all-pass filter networks, at least one of the branches of the all-pass filter networks being electrically tunable to provide an approximately 180&#xb0; phase difference with similar amplitudes of the split signal power to be recombined at the output power combiner for rejecting but substantially absorbing selected frequencies.

Absorptive tunable bandstop filter with wide tuning range and electrically tunable all-pass filter useful therein

An injection locked pulsed oscillator includes a voltage controlled oscillator (VCO) responsive to an injection signal. The injection locked pulsed oscillator includes at least one enable circuit responsive to a first enable signal to enable output pulses from the VCO. The injection locked pulsed oscillator also includes timing circuit responsive to a pulse repetition frequency signal and is configured to provide the injection signal to phase lock the VCO and provide the first enable signal delayed from the injection signal to shape a width of the output pulses from the VCO.

Injection locked pulsed oscillator

A voltage controlled oscillator including an RF output terminal and a DC control terminal, an active circuit, and a resonant circuit interconnected with the active circuit and including a plurality of series resonators each having an electrically variable capacitance and fixed inductor; the active circuit includes at least one transistor having an operating current density which is approximately 35% or less of the peak foperating current density and/or the active circuit includes a multi-transistor bank disposed in at least two separate sections, each pair of sections spaced apart to provide improved thermal uniformity among the transistors without substantially increasing parasitic impedance among them for providing an improved lower phase noise output at said RF output terminal.

Voltage controlled oscillator

A phase shifter includes a low-pass filter, a high-pass filter, and an all-pass filter coupled in series between an RF input terminal and an RF output terminal of the phase shifter, at least one of the filters being tunable, controlling the phase of an input signal over a wide range of frequencies.

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Nashua, NH, United States of America

Cemin Zhang