Abstract: An image sensor has an array of image sensor pixels. Each image sensor pixel may have a gradient index lens formed in a passivation layer. The gradient index lens may be a converging or diverging gradient index lens. The gradient index lens may have a gradient index profile that is smooth or a gradient index profile having distinct regions of lower or higher refractive index. Regions of lower refractive index may be formed from ion implantation in the passivation layer. Each pixel may also have a polymer microlens, a color filter, a dielectric stack, and a photosensitive element in a substrate.

Abstract: A portable computer is provided that has a housing. A removable battery may provide power to the portable computer. A connector on the battery may mate with a corresponding battery connector in the portable computer housing. The battery connector may be mounted in the portable computer housing a floating arrangement. This allows the position of the connector to move slightly to accommodate variations in the position of the battery. A cable may be used to route power between the battery and a main logic board. A cover may be used to hold the battery connector and cable to the housing of the portable computer without excessively impeding movement of the connector.

Abstract: Electrical components such as integrated circuits may be mounted on a printed circuit board. To prevent the electrical components from being subjected to electromagnetic interference, a radio-frequency shielding structure may be mounted over the electrical components. The radio-frequency shielding structure may be formed from a printed circuit that includes a ground plane such as a flex circuit or rigid printed circuit board that includes at least one blanket layer of metal. The printed circuit board to which the electrical components are mounted may include a recess in which the electrical components are mounted. Additional components may be mounted to the interior and exterior surface of the radio-frequency shielding structure. The radio-frequency shielding structure may be formed from a flex circuit that has slits at its corners to accommodate folding.

Abstract: Error detection and error location determination circuitry is provided for detecting and locating soft errors in random-access-memory arrays on programmable integrated circuits. The random-access-memory arrays contain rows and columns of random-access-memory cells. Some of the cells are loaded with configuration data and produce static output signals that are used to program associated regions of programmable logic. Cyclic redundancy check error correction check bits are computed for each column of an array. The cyclic redundancy check error correction check bits are stored in corresponding columns of cells in the array. During normal operation of an integrated circuit in a system, the cells are subject to soft errors caused by background radiation strikes. The error detection and error location determination circuitry uses parallel processing to continuously monitor the data to identify the row and column location of each error.

Abstract: Dual port memory elements and memory array circuitry that utilizes elevated and non-elevated power supply voltages for performing reliable reading and writing operations are provided. The memory array circuitry may contain circuitry to switch a power supply line of a column of memory elements in the array to an appropriate power supply voltage during reading and writing operations. Each memory element may contain circuitry to select between power supply voltages during reading and writing operations. During reading operations, an elevated voltage may power cross-coupled inverters that store data in the memory elements while a non-elevated voltage may be used to turn on associated address transistors. During writing operations, the non-elevated voltage may power the cross-coupled inverters while the elevated voltage may be used to turn on the associated address transistors.

Abstract: Cellular-telephone-based servers are provided that have reduced power consumption. When a cellular-telephone-based server is active, the server may maintain an Internet Protocol (IP) link with a communications network. When no users are connected to the server or at other appropriate times, the cellular-telephone-based server may enter a hibernation state to reduce power consumption. In the hibernation state, the cellular telephone that is running the server may maintain a communications link that supports short messaging service (SMS) messaging and may maintain a communications link associated with control channels that convey control data for cellular telephone communications. A user wishing to connect to the server may send an SMS address request to the server to obtain its IP address. If the server is hibernating, a service controller can activate the server before responding to the SMS address request.

Abstract: Image sensors having image sensor pixels with stacked photodiodes are provided. An image sensor pixel may include a shallow potential well located in a shallow implant region and a deep potential well located in a deep implant region. The shallow implant region and the deep implant region may be separated by a potential barrier. The image sensor pixel may have a given transfer gate to transfer charge from the shallow well to a floating diffusion node. The image sensor pixel may have an additional transfer gate to transfer charge from the deep well to the shallow well via a vertical transfer region located under the additional transfer gate. Image sensor pixels formed using this structure may exhibit higher pixel densities, higher image resolution, and higher sensitivity.

Abstract: Antennas for electronic devices such as portable computers are provided. An antenna may have a dipole structure in which one antenna element serves as a matching element and another antenna element serves as a radiating element. The antenna elements may be mounted on a substrate. The substrate may be mounted on a support structure that is attached to a grounding plate. The grounding plate may be grounded to a conductive housing portion of a portable computer. The antenna may be mounted within the conductive housing in the vicinity of an opening in the housing. The opening may be a slot opening that is used to accommodate optical disks or other storage media. Radio-frequency signals for the antenna may pass through the opening.

Abstract: Electronic devices are provided that contain wireless communications circuitry. The wireless communications circuitry may include radio-frequency transceiver circuitry and antenna structures. A parallel-fed loop antenna may be formed from portions of an electronic device bezel and a ground plane. The antenna may operate in multiple communications bands. An impedance matching circuit for the antenna may be formed from a parallel-connected inductive element and a series-connected capacitive element. The bezel may surround a peripheral portion of a display that is mounted to the front of an electronic device. The bezel may contain a gap. Antenna feed terminals for the antenna may be located on opposing sides of the gap. The inductive element may bridge the gap and the antenna feed terminals. The capacitive element may be connected in series between one of the antenna feed terminals and a conductor in a transmission line located between the transceiver circuitry and the antenna.

Abstract: An electronic device may be provided with a conductive housing. The conductive housing may be formed from a metal. Slots may be formed in the housing. The slots may serve as an antenna and may be fed using an antenna feed structure within the electronic device housing. The electronic device may have a frame to which housing structures are attached and may have a stand or other support structure. The frame may be used to mount a display, to support housing walls, to support clutch barrel structures, etc. The slots may be formed in the frame or in a space between the frame and the housing walls. The slots or other antenna structures may also be formed in the stand. Multiple slots may be used together to support operations in two or more communications bands. There may be multiple dual slot antennas in the electronic device.

Abstract: An electronic device may have a housing with conductive housing walls. A dielectric antenna window may be formed in an opening in one of the conductive housing walls. A dielectric logo may form the dielectric antenna window. A dielectric support structure may have an outline that matches the dielectric logo. An antenna resonating element for an antenna may be formed on the dielectric support structure. An antenna cavity for the antenna may be formed by a conductive cavity structure. A pattern of voids in the dielectric support structure may reduce dielectric loading for the antenna. The conductive cavity structure may be formed from solderable plated metal. The conductive cavity structure may have a planar lip that is attached to the conductive housing walls using conductive adhesive. Rear wall portions of the conductive cavity structure may be oriented at a non-perpendicular non-zero angle with respect to the planar lip.

Abstract: An antenna and button assembly is provided for a compact portable wireless device such as a wireless headset for a handheld electronic device. An antenna structure is mounted within a button structure. The button structure includes a switch actuation member that extends past the antenna structure and into engagement with a switch. The switch actuation member may reciprocate within the button structure. A user may press upon an exposed end of the switch actuation member to operate the switch. The switch may be used to control the application of power to the compact portable wireless device or to perform other suitable functions. The button structure may be formed using dielectric materials such as plastic. By forming the button structure from dielectric, clearance is provided between the antenna structure and conductive portions of the compact portable wireless device so that the antenna of the compact wireless device operates properly.

Abstract: Antenna support structures and antennas are provided for wireless electronic devices such as portable electronic devices. Antenna resonating elements may be formed from conductive coatings on two-shot molded interconnect device dielectric antenna support structures. The conductive coatings may be formed from wet-plated copper or other conductive materials. The antenna support structure may have tabs that electrically connect antenna resonating elements to the case of a wireless electronic device that serves as an antenna ground plane. The antenna support structure may be curved about its longitudinal axis so that the antenna resonating elements on the support structure protrude upwards to enhance antenna performance. In a portable electronic device such as a portable computer, the antenna support structure may be mounted within a dielectric portion of the computer housing that is located between the display portion of the housing and the base of the housing.

Abstract: A low-voltage reference circuit may have a pair of semiconductor devices. Each semiconductor device may have an n-type semiconductor region, an n+ region in the n-type semiconductor region, a metal gate, and a gate insulator interposed between the metal gate and the n-type semiconductor region through which carriers tunnel. The metal gate may have a work function matching that of p-type polysilicon. The gate insulator may have a thickness of less than about 25 angstroms. The metal gate may form a first terminal for the semiconductor device and the n+ region and n-type semiconductor region may form a second terminal for the semiconductor device. The second terminals may be coupled to ground. A biasing circuit may use the first terminals to supply different currents to the semiconductor devices and may provide a corresponding reference output voltage at a value that is less than one volt.

Abstract: This describes color filter arrangements for image sensor arrays that are formed using image sensor pixels with stacked photo-diodes. The stacked photo-diodes may include first and second photo-diodes and may have the ability to separate color signal according to the depth of carrier generation in a silicon substrate. A single color filter may be formed over the stacked photo-diodes to provide full red-green-blue sensing capability. Charge drain regions may also be formed at different depths in the silicon substrate. If the charge drain regions are formed beneath the stacked photo-diodes in the substrate, full red-green-blue color sensing may be achieved without the use of color filters.

Abstract: An integrated circuit is provided with built-in-self test circuitry. The integrated circuit may have multiple blocks of memory. The memory may be tested using the built-in-self test circuitry. Each memory block may include a satellite address generator that is used in generating test addresses for the memory blocks. Each memory block may also include failure analysis logic and output response analyzer logic. Stalling logic may be used to individually stall memory block testing on a block-by-block basis during memory tests. Address buffer circuitry such as first-in-first-out buffers may be used to provide randomized memory addresses during testing.

Abstract: A portable electronic device is provided that has a hybrid antenna. The hybrid antenna may include a slot antenna structure and a planar inverted-F antenna structure. The planar inverted-F antenna structure may be formed from traces on a flex circuit substrate. A backside trace may form a series capacitance for the planar inverted-F antenna structure. The antenna slot may have a perimeter that is defined by the location of conductive structures such as flex circuits, metal housing structures, a conductive bezel, printed circuit board ground conductors, and electrical components. Springs may be used in electrically connecting these conductive elements. A spring-loaded pin may be used as part of an antenna feed conductor. The pin may connect a transmission line path on a printed circuit board to the planar inverted-F antenna structure while allowing the planar inverted-F antenna structure to be removed from the device for rework or repair.

Abstract: Integrated circuits with pulse latches are provided. Pulse latches are controlled by clock pulse signals. The clock pulse signals are generated by pulse generators. The pulse generators are controlled by adaptive pulse width control circuitry to provide clock pulse signals with a minimum pulse width and with sufficient margin to tolerate for process, voltage, and temperature variations. The pulse width control circuitry may include a replica pulse generator, a test data generation circuit, a test latch, and a pulse width calibration circuit. The replica pulse generator controls the test latch. The test latch may attempt to latch the test data. The pulse width control circuit may determine if the test latch properly latches the test data with the given pulse width. The pulse width control circuit adjusts the pulse generator dynamically to provide a minimized pulse width.

Abstract: A halting key derivation function is provided. A setup process scrambles a user-supplied password and a random string in a loop. When the loop is halted by user input, the setup process may generate verification information and a cryptographic key. The key may be used to encrypt data. During a subsequent password verification and key recovery process, the verification information is retrieved, a user-supplied trial password obtained, and both are used together to recover the key using a loop computation. During the loop, the verification process repeatedly tests the results produced by the looping scrambling function against the verification information. In case of match, the trial password is correct and a cryptographic key matching the key produced by the setup process may be generated and used for data decryption. As long as there is no match, the loop may continue indefinitely until interrupted exogenously, such as by user input.

Abstract: Portable electronic devices are provided with wireless circuitry. The wireless circuitry may include one or more sets of radio-frequency power amplifiers. The radio-frequency power amplifiers are used to amplify radio-frequency signals that are transmitted by the portable electronic devices. Each power amplifier may have multiple gain mode settings. Gain stages within the power amplifiers may be selectively enabled in accordance with the gain mode settings. When a higher level of gain is required, all of the gain stages may be enabled. When a lower level of gain is required, some of the gain stages may be disabled to conserve power. An adjustable power supply may be used to provide an adjustable power supply voltage to the power amplifiers. The adjustable power supply voltage can be reduced when it is desired to minimize power consumption at a particular gain mode setting. Gain mode and power supply settings may be adjusted simultaneously.