Silicon Laboratories Inc.

Ligang Zhang

Axel Thomsen

Yunteng Huang

David M Pietruszynski

Daniel J Cooley

Kevin G Smith

Doug Frey

Chengzhou Lin

Sanyi Zhan

Peter Vancorenland

Scott Willingham

Ronald B Hulfachor

Derrick Chunkai Wei

Zhiqi Hu

Ying Shi

Steven P Proffitt

Systems and methods are disclosed for shared AM/FM air loop antennas that may be advantageously implemented to provide a AM/FM receiver system with a single common air loop antenna for receiving both AM and FM channels, thus eliminating the need for additional materials and electronics associated with provision of a separate FM pigtail antenna and FM antenna jack for connection of same. The shared AM/FM air loop antennas may be connected to a radio device having antenna connections.

Air loop antenna for shared AM/FM

A system such as a mechanically tuned radio can have a signal path to receive and process an incoming radio frequency (RF) signal and to provide the processed signal to a first analog-to-digital converter (ADC) to convert the processed signal to a digital signal and to digitally demodulate the digital signal to obtain an audio signal, where this first ADC is separate from an auxiliary ADC not part of the signal path.

Successive approximation register (SAR) analog-to-digital converter (ADC) having optimized filter

Systems and methods are disclosed that use multiple DC-DC (direct-current-to-direct-current) regulators and configurable DC-DC regulators with respect to multi-band audio receivers in order to allow for the use of different DC-DC regulator switching clock signals for different audio broadcast bands. The systems and methods disclosed thereby help to alleviate interference problems typically caused by switching devices used in the DC-DC conversion process. The embodiments described are also applicable to switching power supplies run from alternating current (AC) power sources and to Class D amplifiers working with broadcast radios.

Frequency planning for switching devices for multi-band broadcast radios

Systems and methods are disclosed for an integrated air loop antenna and transformer antenna assembly that provides improved performance in receiving RF signals and AM broadcast channels, in particular. In one embodiment, an air loop antenna is coupled to a transformer to form an integrated antenna assembly. This integrated air loop antenna and transformer antenna assembly can then be connected to a radio device having antenna connections.

Integrated air loop antenna and transformer antenna assembly

A noise cancellation signal is generated for a fractional-N phase-locked loop (). A divide value is provided to a first delta sigma modulator circuit (), which generates a divide control signal to control a divide value of a feedback divider () in the phase-locked loop. An error term (e) is generated that is indicative of a difference between the generated divide control signal and the divide value supplied to the first delta sigma modulator circuit. The error term is integrated in an integrator () to generate an integrated error term (x), where x=x+e; and a phase error correction circuit () utilizes the error term eand the integrated error term xto generate the phase error cancellation signal.

Phase error cancellation

A communications device including communications circuitry, tunable filter circuitry including a node configured to pass a signal between an antenna and the communication circuitry, and control circuitry configured to cause energy in the tunable filter circuitry to be adjusted for a time period and configured to determine a resonant frequency of the tunable filter circuitry from oscillations on the node caused by the energy subsequent to the time period is provided.

System and method for determining a resonant frequency in a communications device

Jitter is measured by receiving a first reference signal at a first phase-locked loop (PLL) circuit and generating at an output of the first phase-locked loop circuit an output signal based at least in part on the first reference signal, the output signal including a jitter component to be measured. A signal corresponding to the output signal and a signal corresponding to the first reference signal are compared in a phase detector of a second phase-locked loop circuit. A value corresponding to an output of the comparison is stored that includes information indicative of the measured jitter component.

Jitter self test

An oscillator circuit formed at least partially on an integrated circuit substrate includes a self-shielding inductor. The self-shielding inductor has a toroidal structure. A coil forms a structure that is symmetric around an axis orthogonal to a surface of the integrated circuit substrate. A magnetic filed generated by the self-shielding inductor is confined to a core region of the coil. Portions of the self-shielding inductor may be formed in integrated circuit layers, redistribution layers, package layers, through-substrate interconnect, backside substrate conductor layers, or combinations thereof.

Self-shielding inductor

An improved electromagnetic shielding structure has been discovered. In one embodiment of the invention, an apparatus includes an inductor and an electrically conductive enclosure that electromagnetically shields the inductor. The electrically conductive enclosure has an aperture at least as large as the inductor. The aperture is substantially centered around a projected surface of the inductor. The apparatus may include one or more electrically conductive links extending across the aperture and electrically coupled to the electrically conductive enclosure. The electrically conductive links reduce an effect of electromagnetic signals external to the electrically conductive enclosure on the inductor.

Electromagnetic shielding structure

A region of high metal density may be placed in metal layers proximate to an area of low metal density below an inductor on an integrated circuit without violating manufacturing design rules for reducing manufacturing defects and without substantially impacting performance of the inductor. These results are achieved by including a transitional region that includes conductive structures electrically isolated from each other between the region of high metal density and the region of low metal density. The transitional region has a structure that allows a negligible amount of current flow to be induced in the structure.

Method and structure for forming relatively dense conductive layers

The effect of supply voltage variations on an oscillator circuit output are compensated for to reduce supply pushing. The change in a value of a first capacitance in a first direction in response to the variation in the supply voltage is canceled using one or more diodes having a capacitance that changes in a second direction, opposite the first direction, in response to the variation in the supply voltage.

Push compensation in an oscillator

A locking range of a current mode logic (CML) frequency divider circuit is tunable by dynamically adjusting a tail current of the frequency divider circuit according to a control signal. The control signal may be based on at least one control signal coupled to tune a controllable oscillator. The control signal may be based on a frequency of an output of a voltage controlled oscillator coupled to the frequency divider. The control signal may be based on the voltage swing of an output of a voltage controlled oscillator coupled to the frequency divider. The control signal may be based on an output of the frequency divider circuit.

Tunable high-speed frequency divider

It has been discovered that an inductor may be made to include a surface rotational portion instead of a coil to provide a low inductance inductor with sufficient quality factor. The surface rotational portion is a conducting structure which is substantially enclosed along the length of the structure and which has openings at each end of the structure and an opening along the length of the structure between the end openings. One example of such a structure is a cylinder having a lateral opening and openings at its ends or bases. Another example of such a structure is a duct-shape or rectangular structure. Any appropriately shaped surface may be used to rotate current, and varying thicknesses and lengths may be used as appropriate.

Surface inductor

A variable capacitance circuit includes a first and a second capacitor. A switch having an associated first nonlinear capacitance, selectively couples the first and second capacitors. To compensate for the first nonlinear capacitance, a second nonlinear capacitance is coupled to the switch that has a capacitance value responsive to a change in voltage that moves in a direction of change opposite to a direction of change of the first nonlinear capacitance.

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Austin, TX, United States of America

Ligang Zhang