Abstract: In one embodiment the present invention includes a method of calibrating the frequency response of a transmitter comprising generating a plurality of calibration tones across a frequency range, coupling the plurality of calibration tones to an input of said transmitter, detecting the plurality of calibration tones at an output in said transmitter, and in accordance therewith, generating a plurality of calibration values, receiving digital data to be transmitted, the digital data comprising a plurality of frequency components in said frequency range, and calibrating said frequency components of said digital data using the calibration values.

Abstract: In one embodiment the present invention include systems and methods for synchronizing wireless communication systems. In one embodiment, a baseband processor includes a reference frequency for synchronizing processing of received data. The baseband processor may detect received data and determine frequency hopping sequences to program a frequency synthesizer. The baseband processor may synchronize the synthesizer's frequency changes to receive incoming data. Symbols received by the system may be detected and used to start the reference frequency. In one embodiment, the reference frequency has a period equal to the symbol period. Cross-correlators may be used to detect frequency hopping patterns. Clusters of results from the cross-correlators may be analyzed and the results used to control timing of the system.

Abstract: Embodiments of the present invention include techniques for performing cross correlations. In one embodiment the present invention includes a cross correlation system for use in a communication system comprising a wireless receiver receiving a signal including a first sequence of data values and converting the first sequence of data values into a sequence of digital data values, the wireless receiver further comprising a plurality of cross correlators that each receive the digital data values and cross correlate the digital data values with a corresponding plurality of different binary reference patterns, wherein if the first sequence of data values correlates with one of said plurality of binary reference patterns, one of said cross correlators generates a peak. In one embodiment, the cross correlators are partitioned into stages. In another embodiment, the received data values are loaded into a memory that is shared by the cross correlators to reduce hardware requirements.

Abstract: Embodiments of the present invention include programmable filter circuits and methods. In one embodiment, the present invention includes a programmable filter for filtering an input signal comprising a storage element for storing a plurality of digital values representing a discrete time window function, and a plurality of filter channels, each channel comprising a multiplying digital-to-analog converter having a plurality of digital inputs coupled to the storage element and an analog input for receiving said input signal to be filtered, at least one capacitor having at least one terminal coupled to an output of the multiplying digital-to-analog converter, and a sampling device coupled between the at least one terminal of the at least one capacitor and an output of the filter. In another embodiment, the present invention includes a software defmed radio.

Abstract: Embodiments of the present invention include circuits and methods with wide bandwidths. In one embodiment, parasitic capacitances of the output of a first stage and the input of a second stage are included in a network. The output of the first stage is coupled to the input of the network, and the input of the second stage is coupled to an intermediate node of the network. In one embodiment, the parasitic capacitance of the second stage is the largest capacitance in the network.

Abstract: Embodiments of the present invention include circuits and methods for improving the spectral purity of mixer circuits. In one embodiment the present invention includes a mixer circuit comprising a first transistor having a gate, a source and a drain, a second transistor having a gate, a source and a drain, a first capacitance coupled between the source of the first transistor and the source of the second transistor and a bias circuit having an input, a first output coupled to the source of the first transistor and a second output coupled to the source of the second transistor. The present invention may be advantageously used in a wireless transmitter application.

Abstract: Embodiments of the present invention include circuits and methods for improving the spectral purity of mixer circuits. In one embodiment the present invention includes a mixer circuit including a bias circuit, the bias circuit comprising a first transistor having a gate, a source, and a drain, wherein the drain is coupled to a first input of the mixer circuit, a first sensing circuit coupled to the source of the first transistor, and a first comparison circuit coupled to the first sensing circuit, wherein the first comparison circuit receives a feedback signal from the first sensing circuit and a reference voltage, and in accordance therewith, generates a bias control signal to control the bias at the gate of the first transistor.

Abstract: Embodiments of the present invention include wideband attenuator circuits and methods. In one embodiment the present invention includes a first divider circuit coupled in series with two or more second divider circuits. The divider circuits include resistance and capacitance values that may be set according to particular relationships. In one embodiment, a wideband attenuator may include capacitors that are selectively coupled to each output node.

Abstract: Embodiments of the present invention include mixer circuits and methods with improved spectral purity. In one embodiment the present invention includes a mixer circuit comprising a first transistor having a gate, a source and a drain, a second transistor having a gate, a source and a drain, a first capacitance coupled between the source of the first transistor and the source of the second transistor and a bias circuit having an input, a first output coupled to the source of the first transistor and a second output coupled to the source of the second transistor. The present invention may be advantageously used in a wireless transmitter application.

Abstract: Embodiments of the present invention include circuits for use in wireless receivers that provide wide band matching with improved gain and noise performance. In one embodiment, the present invention includes a wireless receiver comprising an antenna, a first transistor having a source coupled to the antenna, a second transistor having a gate coupled to the antenna and a network comprising a first terminal coupled to the antenna, a second terminal coupled to the source of the first transistor and a third terminal coupled to the gate of the second transistor, wherein the network has a transimpedance between the second and third terminals so that noise generated by the first transistor is differentially rejected by the system across a predetermined range of frequencies.

Abstract: Embodiments of the present invention include circuits and methods with wide bandwidths. In one embodiment, parasitic capacitances of the output of a first stage and the input of a second stage are included in a network. The output of the first stage is coupled to the input of the network, and the input of the second stage is coupled to an intermediate node of the network. In one embodiment, the parasitic capacitance of the second stage is the largest capacitance in the network.

Abstract: Embodiments of the present invention include circuits and methods with wide bandwidths. In one embodiment, parasitic capacitances of the output of a first stage and the input of a second stage are included in a network. The output of the first stage is coupled to the input of the network, and the input of the second stage is coupled to an intermediate node of the network. In one embodiment, the parasitic capacitance of the second stage is the largest capacitance in the network. In another embodiment, passive networks are coupled to the outputs of a stage, and one or more current injection circuits may be used to extend the bandwidth of the circuit.

Abstract: Embodiments of the present invention include circuits and methods for dividing signals. In one embodiment the present invention includes a divider circuit comprising at least one first divider input receiving an in-phase (I+) signal, at least one second divider input receiving a complement of the in-phase (I?) signal, at least one third divider input receiving a quadrature (Q+) signal, and at least one fourth divider input receiving a complement of the quadrature (Q?) signal. In one embodiment, the lock range of a divider is improved by providing a first bias current greater than a second bias current.

Abstract: Embodiments of the present invention include a frequency synthesizer comprising a first plurality of dividers receiving a first signal having a first frequency and generating a first plurality of divided signals and a frequency combination network including a plurality of mixers, the frequency combination network receiving one or more of the first plurality of divided signals and generating a plurality of synthesized signals having different frequencies. The frequency combination network may further include additional dividers and multiplexers for more flexibility in synthesizing different frequencies. In one embodiment, the frequency combination network is coupled to dividers in the feedback path of a phase locked loop. The present invention is particularly advantageous for synthesizing frequencies above one (1) gigahertz.

Abstract: Embodiments of the present invention include circuits and methods for dividing high frequency signals. In one embodiment the present invention includes a divider circuit comprising a differential circuit having first and second inputs to receive a first differential signal, a first frequency control input and first and second differential outputs, wherein the differential circuit has a first bias current. The divider circuit further includes a cross-coupled circuit having outputs coupled to the differential circuit outputs and a second frequency control input, wherein the cross-coupled circuit has a second bias current. Embodiments of the present invention may include circuits for controlling the relationship between bias currents and circuit parameters that vary with process or temperature or both.

Abstract: Embodiments of the present invention include circuits and methods for reducing DC Offset. In one embodiment the present invention includes storing DC offset on internal capacitances. In one embodiment, parallel stages are used to remove DC offset corresponding to different local oscillator frequencies. Embodiments of the invention further include changing the low cutoff frequency of the DC cancellation circuits for fast calibration. In a first state, a high pass filter may have a first low cutoff frequency, and in a second state the high pass filter may have a second cutoff frequency lower than the first low cutoff frequency. The present invention also includes a variable gain amplifier with reduced DC offset.

Abstract: Embodiments of the present invention include wideband attenuator circuits and methods. In one embodiment the present invention includes a first divider circuit coupled in series with two or more second divider circuits. The divider circuits include resistance and capacitance values that may be set according to particular relationships. In one embodiment, a wideband attenuator may include capacitors that are selectively coupled to each output node.

Abstract: Embodiments of the present invention include mixer circuits and methods with improved spectral purity. In one embodiment the present invention includes a mixer circuit comprising a first transistor having a gate, a source and a drain, a second transistor having a gate, a source and a drain, a first capacitance coupled between the source of the first transistor and the source of the second transistor and a bias circuit having an input, a first output coupled to the source of the first transistor and a second output coupled to the source of the second transistor. The present invention may be advantageously used in a wireless transmitter application.

Abstract: Embodiments of the present invention include circuits and methods for improving the spectral purity of mixer circuits. In one embodiment the present invention includes a mixer circuit including a bias circuit, the bias circuit comprising a first transistor having a gate, a source, and a drain, wherein the drain is coupled to a first input of the mixer circuit, a first sensing circuit coupled to the source of the first transistor, and a first comparison circuit coupled to the first sensing circuit, wherein the first comparison circuit receives a feedback signal from the first sensing circuit and a reference voltage, and in accordance therewith, generates a bias control signal to control the bias at the gate of the first transistor.

Abstract: Embodiments of the present invention include circuits for use in wireless receivers that provide wide band matching with improved gain and noise performance. In one embodiment, the present invention includes a wireless receiver comprising an antenna, a first transistor having a source coupled to the antenna, a second transistor having a gate coupled to the antenna and a network comprising a first terminal coupled to the antenna, a second terminal coupled to the source of the first transistor and a third terminal coupled to the gate of the second transistor, wherein the network has a transimpedance between the second and third terminals so that noise generated by the first transistor is differentially rejected by the system across a predetermined range of frequencies.