摘要:
This patent describes a method of removing the LO-leakage and 1/f noise problems associated with direct conversion RF receivers and other demodulators. In order to solve this problem a virtual LO™ signal is generated within the RF signal path 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 LO frequency. Any errors in generating the virtual LO signal are minimized using a closed loop correction scheme.
摘要:
The invention describes improvements to a balanced active demodulator subsystem implemented in Radio Frequency integrated circuit technology that simplify the configuration and set-up of a balanced demodulator section and reduce the labor and time required during manufacture to adjust the demodulation characteristics for optimum performance. The subsystem allows for the selection of various combinations of components during use, during configuration and set-up, or during both phases, and comprises a mixer, a plurality of parallel RF balanced amplifier input stages operationally connected to the mixer, a first set of switches arranged to permit the independent selection and making operable one of the RF balanced amplifier stages, a number of pairs of current sources arranged to provide bias currents for the RF balanced amplifier input stages to reduce the current required to be passed through the balanced demodulator section; and a second set of switches arranged to permit the independent selection and making operable one of said pairs of current sources. The invention provides a balanced demodulator subsystem suitable for use in products in which cost-effectiveness is a critical factor, such as those used in personal communications.
摘要:
This patent describes a method and system which overcomes the LO-leakage problem of direct conversion and similar RF transmitters and receivers. To solve this problem a virtual LO™ signal is generated which emulates mixing with a local oscillator (LO) signal. However, 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, so there is no LO component to leak to the output. The invention also does not require sophisticated filters or large capacitors as other designs in the art, so it is fully integratable.
摘要:
An inexpensive, high-performance, fully-integrable, multi-standard transceiver with a topology including: an active mixer, followed by a high pass filter, and a passive mixer. The input signal is modulated up, or demodulated down, using a pair of complementary, aperiodic mixing signals. The use of aperiodic mixing signals allows a fully-integrated transceiver to be built. Embodiments of the active mixer include those having electrically-adjustable performance and allowing multiple RF signal inputs. This allows the topology to be employed in multi-band, multi-frequency applications, while still providing high performance.
摘要:
This patent describes a method and system which overcomes the LO-leakage problem during modulation and demodulation, common to direct conversion and similar RF transmitters and receivers. This problem is solved using a virtual local oscillator (VLO™) signal which emulates mixing with a local oscillators (LO) signal. The VLO signal is constructed using complementary mixing signals that suppress mixing power in the bandwidth of the input signal, and within the bandwidth of the output frequency. Specifically, mixing is done in two or more stages, using time-varying mixing signals φ1 and φ2 which satisfy the following criteria: φ1*φ2 having significant power at the frequency of the LO being emulated, one of φ1 and φ2 having minimal power around the frequency of the output signal y(t), and the other of φ1 and φ2 having minimal power around the center frequency, fRF, of the input signal x(t).
摘要:
An inductive coupling apparatus for modifying an incoming radio frequency (RF) signal includes an inductive element. A variable impedance circuit includes an output electrically coupled to the inductive element. A band-pass delta sigma modulator is coupled to the variable impedance circuit and digitally controls the output of the variable impedance circuit. The incoming RF signal is modified as the coupled impedance of the inductive element is adjusted in accordance with the output of the variable impedance circuit.
摘要:
An inductive coupling apparatus for modifying an incoming radio frequency (RF) signal includes an inductive element for modifying the incoming RF signal in accordance with a coupled impedance characteristic of the inductive element. A variable impedance circuit includes an output electrically coupled to the inductive element. A low pass delta sigma modulator is coupled to the variable impedance circuit and digitally controls the output of the variable impedance circuit, the coupled impedance of the inductive element being adjusted based on the output of the variable impedance circuit.
摘要:
A radio transceiver including a transmitter and a receiver. A filter coupled to an output of the transmitter, the filter has one or more inductors and one or more capacitors, where the filter is tuned by varying one or more capacitance values of the one or more capacitors in the filter to tune the filter. The one or more capacitors are Barium Strontium Titanate (BST) ceramic integrated capacitors that are each tuned by application of a bias voltage thereto. A filter tuner circuit is configured to apply the bias voltage to the one or more capacitors, where the bias voltage is initially established as a stored initial value, and where the bias voltage is refined by a proportional-integral-derivative (PID) controller configured to optimize a power within the transceiver. This abstract is not to be considered limiting since various implementations may incorporate more, fewer or different elements.
摘要:
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.
摘要:
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; and use the validation credentials to validate the wireless communication device with the second access point to obtain access to the network.