Abstract:
An antenna apparatus for backscattering an incoming radio frequency (RF) signal includes an antenna for backscattering the incoming RF signal in accordance with a reflection coefficient characteristic of the antenna. A variable impedance circuit includes an output electrically connected to the antenna. A band-pass delta sigma modulator is coupled to the variable impedance circuit and digitally controls the output of the variable impedance circuit, such that the reflection coefficient of the antenna is adjusted based on the digitally controlled output of the variable impedance circuit. In an RFID network, the apparatus and method reduces the effect of DC offset in the reader device and the effects of the reader device's phase noise, while allowing for complex modulations.
Abstract:
A system is provided to facilitate communication with a client via both a first network and a second network. The system comprises a plurality of bandwidth aggregation servers, each bandwidth aggregation server configured to aggregate data packets received from the client via both the first and second networks for transmission to a destination server; and transmit data packets to the client via both the first and second networks in accordance with a scheduling algorithm, the data packets being received from a source server.
Abstract:
The invention is directed at a hybrid modulation apparatus which combines a polar modulation circuit and a linear modulation circuit. The hybrid apparatus allows a communications device to function as a polar or a linear modulation circuit with less components as the output of the linear modulation circuit is an input of the polar modulation circuit.
Abstract:
A method and system for dynamically shifting spurious tones away from the desired frequency in a virtual local oscillator receiver, such that any undesired signal residing at such spurious tones are effectively delineated from the desired signal and removed from the RF input signal. The system detects the presence of potential undesired blocker signals in the RF input signal, and initiates an iterative power comparison and mixer signal adjustment loop. As the virtual local oscillator uses two mixer signals, the frequency of one of the mixer signals is adjusted during the loop until the power of the down-converted signal is minimized to a predetermined level. Minimized power in the down-converted signal is indicative of the absence of the blocker signal, since the presence of a relatively high power signal is indicative of a blocker signal overlapping with a desired signal.
Abstract:
The present invention relates generally to communications, and more specifically to a method and apparatus for generating local oscillator signals used for up- and down-conversion of RF (radio frequency) signals. A major problem in the design of modulators and demodulators, if the leakage of local oscillator (LO) signals into the received signal path. The invention presents a number of highly integratable circuits which resolve the LO leakage problem, using regenerative divider circuits acting on oscillator signals which are running at a multiple or fraction of the frequency of the desired LO signal, to generate in-phase (I) and quadrature (Q) mixing signals. Embodiments of these circuits also use harmonic subtraction and polyphase mixers, as well as virtual local oscillator TM (VLO) mixing signals. VLO mixing signals are signal pairs which emulate local oscillator signals by means of complementary mono-tonal and multi-tonal mixing signals.
Abstract:
A system for generating a supply voltage, temperature and process compensated gain control voltage from a digital data word. In particular, the compensated gain voltage control voltage maintains a linear relationship between a change in gain in response to an input gain control voltage for a gain circuit of a transmitter circuit. A monitor circuit senses at least one of the supply voltage, temperature and process parameters, and generates a first set of digital signals corresponding to the sensed parameter. A digital compensator circuit converts the input gain control voltage into a second set of digital signals, and decodes the combined first and second set of digital signals to provide a data word. The data word is converted into an analog voltage representing the compensated gain voltage control voltage. The digital compensator circuit includes a table of compensation values, each accessible by a distinct combination of the first and second set of digital signals.
Abstract:
This patent describes a method and system which overcomes the LO-leakage problem of direct conversion and similar RF transmitters. To solve this problem a virtual LO™ signal is generated within the baseband which is tuned to the incoming RF signal. The virtual local oscillator (VLO) signal is constructed using signals that do not contain a significant amount of power (or no power at all) at the wanted output RF frequency. Any errors is generating the virtual LO signal are minimized using a closed loop correction scheme.
Abstract:
An integrated radio frequency (RF) coupling scheme is provided for realizing low voltage RF integrated circuits. According to the invention, on-chip capacitively coupled resonant elements are used to DC isolate circuit block elements which are required to be connected in series and share a common DC current. The coupling scheme according to the present invention may be applied to several commonly used RF integrated circuit topologies such as low noise amplifiers and mixers.
Abstract:
A digital-to-analog converter is disclosed. The converter includes a gradient correction module that generates a correction term based on a model of gradient error. The correction term is then applied to the signal path in the digital domain or applied to the output of the digital-to-analog converter in the analog domain. The model used to generate the correction term is based on a vertical gradient error in the array of current source elements, which may be modelled and calibrated using a second-order polynomial. Further, a digital-to-analog converter having a Nyquist DAC and an oversampled DAC is disclosed. When the oversampled DAC is enabled, the resolution of the Nyquist DAC may be increased while slowing the conversion rate.
Abstract:
A wireless communication device is configured to be able to communicate via both a first access point and a second access point for using the first access point to obtain validation credentials in order to permit use of the second access point to access a network. The wireless communication device comprises a processor; and a non-transitory computer readable medium having stored thereon computer executable instructions. The instructions are operable to: initiate communication with the second access point in order to access a network; obtain an access point identifier from the second access point, the access point identifier for identifying the second access point; transmit the access point identifier to a validation server via the first access point; receive validation credentials from the validation server via the first access point; the validation credentials including at identifier of a third party, the third party sponsoring access to the second access point; use the validation credentials to validate the wireless communication device with the second access point to obtain access to the network; and present advertising information on the wireless communication device, the advertising information pertaining to the third party.