A system and a method are provided for reducing the effects of spurious frequencies in a wireless communications device. The system comprises a processor having a reference frequency input and a clock having an output connected to the processor input. The clock supplies a clock frequency, or reference frequency, to the processor. The reference frequency is the frequency at which the processor operates. The clock also has an input for selecting a reference frequency to provide to the processor. T...

A circuit where the same amplifiers and the same volume adjustment circuitry are used for the ringer mode as well as for the audio mode of a mobile phone is achieved. The volume adjustment in the audio and ringer mode is provided by a precise amplitude setting via the gain control stages of an inverting voltage amplifier used in a bridge circuit through a current-voltage conversion. This volume adjustment circuit avoids the high power dissipation of a volume control through pulse width modulatio...

A variable bandwidth, sampled analog filter can be programmed to have a variety of responses. A variable bandwidth, sampled analog filter is preferably a sampled analog resonator based filter that receives a bandwidth control input and a sample clock input. The sampled analog resonator units can include clock delay circuits and reversible (loss/gain) attenuators.

A digital amplitude modulation (AM) transmitter with pulse width modulating RF drive is presented. A plurality of RF amplifiers, each, when turned on, amplifies an applied RF drive signal by the same amount to provide a unit step RF output. An encoder supplies turn-on signals to turn on a number of the RF amplifiers wherein the number varies as a function of the value of an applied audio signal. The width of the unit step RF output is varied as a function of the number of the RF amplifiers that ...

A wireless node, such as a sensor node or other suitable node, includes a supercapacitor having a charge and one or more photocells adapted to charge the supercapacitor responsive to ambient light. A microprocessor cooperates with a wireless transceiver to transmit a count of one or more wireless messages. The microprocessor determines the charge of the supercapacitor, determines an incremental charge of the supercapacitor resulting from the ambient light, and adjusts the count of the wireless m...

Methods for remote control of a wireless unit such as remote power-on and remote power-off. An authorized user may send a power-on communication to a remote wireless unit. The power-on communication may be sent by way of an activation system. The wireless unit may be in a sleep state or be turned-off. In response to receipt of the power-on communication or a signal from the activation system, the wireless unit powers-on and may power-on through a remote power-on function. The power-on communicat...

An integrated circuit radio receiver includes radio frequency ("RF") front end circuitry for receiving and transmitting digital data received through a wireless interface. A baseband processor is operable to process the digital data received through the wireless interface. A first logic is operable to provide a first level of digital filtering for a first received digital data signal format. A second logic is operable to provide the first level of digital filtering and derotation for a second re...

A system and method are provided for compensating for an I/Q mismatch of either a direct conversion transmitter or a direct conversion receiver based on known short training symbols of a Short Training Sequence (STS) of packets transmitted according to the IEEE 802.11a or 802.11g standard. To compensate for an I/Q mismatch of a direct conversion transmitter, a packet including the STS is transmitted. Due to the I/Q mismatch of the direct conversion transmitter, the transmitter distorts the packe...

An RF switching circuit that incorporates a film bulk acoustic resonator (FBAR) device and one or more capacitors that are used to vary the capacitance of the FBAR device to change the frequency range that is blocked by the FBAR device. When the RF switching circuit is in a first switching state, a first set of RF signals in a first frequency range is blocked by the RF switching circuit while RF signals of other frequencies are passed by the RF switching circuit. When the RF switching circuit is...

A quadrature mixer with an LO input is provided. The quadrature mixer receives a signal having a frequency F.sub.LO and a signal input having a frequency F.sub.SIG, and has an output that comprises an output impedance that is high at frequencies of |F.sub.LO-F.sub.SIG | and |F.sub.LO+F.sub.SIG| and low at other. A mixer coupled to the output impedance interacts with the output impedance such that an impedance presented at the signal input is high for signals at F.sub.SIG if F.sub.SIG is a predet...