Abstract: A wireless communication system is provided that detects a frequency burst (FB) through analysis of the autocorrelation function of received signals. The system can accommodate the relatively large frequency offsets that are associated with less expensive reference frequency crystals. In one embodiment, the system includes FB search hardware that operates in two modes, namely an FB location mode with narrowband interference (e.g. CW or continuous wave) detection and an FB location mode without such narrowband interference detection, depending on whether a CW signal (carrier or other narrowband interferer) is present or not.

Abstract: A synchronous read channel having a single chip integrated circuit digital portion which provides digital gain control, timing recovery, equalization, digital peak detection, sequence detection, RLL(1,7) encoding and decoding, error-tolerant synchronization and channel quality measurement is disclosed. The integrated circuit accommodates both center sampling and side sampling, and has a high degree of programmability of various pulse shaping and recovery parameters and the ability to provide decoded data using sequence detection or digital peak detection. These characteristics, together with the error-tolerant sync mark detection and the ability to recover data when the sync mark is obliterated, allow a wide variety of retry and recovery strategies to maximize the possibility of data recovery.

Abstract: Receiver architectures and related methods are disclosed for high definition (HD) and digital radio FM broadcast receivers. The radio receiver architectures are configured to utilize multiple analog-to-digital converters (ADCs) to handle the digital radio spectrum and can be configured to modify a target IF frequencies depending upon the mode of operation of the receiver. For example, the receiver can include an analog FM reception mode and a digital FM reception mode for which different down-conversions are used for the same analog-plus-digital audio broadcast channel. If desired, the radio broadcast receivers disclosed can be configured so that they only receive digital FM radio content, for example, if the analog FM broadcast was of no interest and/or if the broadcast was all digital.

Abstract: Radio-frequency (RF) apparatus includes receiver analog circuitry that receives an RF signal and provides at least one digital signal to receiver digital circuitry that functions in cooperation with the receiver analog circuitry. The receiver analog circuitry and the receiver digital circuitry are partitioned so that interference effects between the receiver analog circuitry and the receiver digital circuitry tend to be reduced.

Abstract: A synchronous read channel having a single chip integrated circuit digital portion which provides digital gain control, timing recovery, equalization, digital peak detection, sequence detection, RLL(l,7) encoding and decoding, error-tolerant synchronization and channel quality measurement is disclosed. The integrated circuit accommodates both center sampling and side sampling, and has a high degree of programmability of various pulse shaping and recovery parameters and the ability to provide decoded data using sequence detection or digital peak detection. These characteristics, error-tolerant sync mark detection, and the ability to recover data when the sync mark is obliterated allow a wide variety of retry and recovery strategies to maximize the possibility of data recovery.

Abstract: Radio-frequency (RF) apparatus includes receiver analog circuitry that receives an RF signal and provides at least one digital signal to receiver digital circuitry that functions in cooperation with the receiver analog circuitry. The receiver analog circuitry and the receiver digital circuitry are partitioned so that interference effects between the receiver analog circuitry and the receiver digital circuitry tend to be reduced.

Abstract: Components of a radio-frequency (RF) apparatus including transceiver circuitry and frequency modification circuitry of a crystal oscillator circuit that generates a reference signal with adjustable frequency may be partitioned in a variety of ways, for example, as one or more separate integrated circuits. The frequency modification circuitry may be implemented as part of a crystal oscillator circuit that includes digitally controlled crystal oscillator (“DCXO”) circuitry and a crystal. The frequency modification circuitry may include at least one variable capacitance device and may be employed to generate a reference signal with adjustable frequency. The adjustable reference signal may be provided to other components of the RF apparatus and/or the RF apparatus may be configured to provide the adjustable reference signal to baseband processor circuitry.

Abstract: A radio-frequency receiver circuitry includes a down-converter circuitry, an analog-to-digital converter circuitry, and a DC offset reduction circuitry. The down-converter circuitry accepts a received radio-frequency signal and processes the radio-frequency signal to provide an in-phase down-converted signal and a quadrature down-converted signal to the analog-to-digital converter circuitry. The analog-to-digital converter circuitry converts the in-phase and quadrature down-converted signals to an in-phase digital output signal and a quadrature digital output signal, respectively. The DC offset reduction circuitry couples to the analog-to-digital converter circuitry, and tends to reduce a DC offset transmitted to the in-phase and quadrature digital output signals.

Abstract: Components of a radio-frequency (RF) apparatus including transceiver circuitry and frequency modification circuitry of a crystal oscillator circuit that generates a reference signal with adjustable frequency may be partitioned in a variety of ways, for example, as one or more separate integrated circuits. The frequency modification circuitry may be implemented as part of a crystal oscillator circuit that includes digitally controlled crystal oscillator (“DCXO”) circuitry and a crystal. The frequency modification circuitry may include at least one variable capacitance device and may be employed to generate a reference signal with adjustable frequency. The adjustable reference signal may be provided to other components of the RF apparatus and/or the RF apparatus may be configured to provide the adjustable reference signal to baseband processor circuitry.

Abstract: A low-noise current reference circuitry includes a voltage source, a current source, and a controller. The voltage source generates a reference voltage. The current source provides a low-noise output current in response to a control signal. The controller provides the control signal based at least in part on the relative magnitudes of the reference voltage and a voltage derived from the output current. A low-noise voltage reference circuitry includes a reference voltage source, a voltage source, and a controller. The reference voltage source generates a reference voltage. The voltage source provides a low-noise output voltage in response to a control signal. The controller provides the control signal based at least in part on the relative magnitudes of the output voltage and the reference voltage.

Abstract: A buffer circuitry buffers a radio-frequency (RF) signal. The buffer circuitry includes a complementary pair of switches and a power source. The a complementary pair of switches has an input terminal and output terminal. The input terminal of the complementary pair of switches responds to the RF signal. The output terminal of the complementary pair of switches couples to an output of the buffer circuitry. The power source includes a capacitor coupled to a current source. The power source couples to the complementary pair of switches. The power source supplies power to the complementary pair of switches in a manner that the buffer circuitry supplies a substantially constant power level at its output.

Abstract: A radio-frequency (RF) apparatus capable of transmitting RF signals includes transmitter path circuitry. The transmitter path circuitry includes a voltage-controlled oscillator (VCO) that generates an output signal. The frequency of the output signal of the VCO circuitry is adjustable in response to a first control signal and a second control signal. The transmitter path circuitry also includes a first feedback circuitry and a second feedback circuitry that are responsive to the output signal of the VCO circuitry. The first feedback circuitry provides the first control signal to the VCO circuitry. The first control signal coarsely adjusts the frequency of the output signal of the VCO circuitry to a desired frequency. The second feedback circuitry supplies the second control signal to the VCO circuitry. The second control signal fine tunes the frequency of the output signal of the voltage-controlled oscillator circuitry to the desired frequency.

Abstract: A radio-frequency (RF) apparatus includes front-end circuitry. The front-end circuitry includes a filter circuitry and an impedance matching circuitry. The filter circuitry has a differential output that has an output impedance. The filter circuitry filters signals outside a signal band of interest. The impedance matching network has a differential input coupled to the output of the filter circuitry. The impedance matching network also has a differential output coupled to a signal processing circuitry. The signal processing circuitry has an input impedance. The impedance matching network matches the input impedance of the signal processing circuitry to the output impedance of the filter circuitry.

Abstract: A calibration circuitry includes an adjustable capacitor, a voltage generator, a reference voltage generator, and a controller. The reference voltage generator provides a reference voltage. The voltage generator provides a measurement voltage that depends on the capacitance of the adjustable capacitor. The capacitance of the adjustable capacitor varies in response to a control signal. The controller provides the control signal based on the relative values of the reference voltage and the measurement voltage.

Abstract: A radio-frequency (RF) receiver includes a receiver analog circuitry and a receiver digital circuitry coupled together. The receiver analog circuitry receives an RF signal. The receiver analog circuitry processes the received RF signal and generates a digital signal that it provides to the receiver digital circuitry. The receiver digital circuitry includes a digital down-converter circuitry that mixes the digital signal provided by a receiver analog circuitry with a digital intermediate frequency (IF) local oscillator signal to generate a digital down-converted signal. The receiver digital circuitry also includes a digital filter circuitry that filters the digital down-converted signal to generate a filtered digital signal. The digital filter circuitry provides a notch at a frequency that corresponds to a residual DC offset of the receiver analog circuitry.

Abstract: A radio-frequency (RF) apparatus capable of transmitting RF signals includes transmitter path circuitry. The transmitter path circuitry includes a voltage-controlled oscillator (VCO) circuitry. The VCO circuitry generates a first signal that has a first frequency. A divider circuitry couples to the VCO circuitry and, in response to the first signal, the divider circuitry generates a second signal that has a second frequency. The frequency of the second signal equals the frequency of the first signal divided by a number.

Abstract: A radio-frequency (RF) receiver includes a receiver analog circuitry and a receiver digital circuitry. The receiver analog circuitry resides within a first integrated circuit and the receiver digital circuitry resides within a second integrated circuit. The second integrated circuit couples to the first integrated circuit via a one-bit digital interface. The receiver analog circuitry receives an RF signal and processes the received RF signal to generate a digital signal. The receiver analog circuitry provides the digital signal to the receiver digital circuitry. The receiver digital circuitry includes a digital down-converter circuitry that mixes the digital signal with an intermediate frequency (IF) local oscillator (LO) signal to generate a digital down-converted signal. The receiver digital circuitry also includes a digital filter circuitry that filters the digital down-converted signal to generate a filtered digital signal.

Abstract: A sampled amplitude read channel for magnetic disk recording which asynchronously samples the analog read signal, adaptively equalizes the resulting discrete time sample values according to a target partial response, extracts synchronous sample values through interpolated timing recovery, and detects digital data from the synchronous sample values using a Viterbi sequence detector is disclosed. To minimize interference from the timing and gain control loops, the phase and magnitude response of the adaptive equalizer filter are constrained at a predetermined frequency using an optimal orthogonal projection operation as a modification to a least mean square (LMS) adaptation algorithm. Further, with interpolated timing recovery, the equalizer filter and its associated latency are removed from the timing recovery loop, thereby allowing a higher order discrete time filter and a lower order analog filter.

Abstract: Radio-frequency (RF) apparatus includes receiver analog circuitry that receives an RF signal and provides at least one digital signal to receiver digital circuitry that functions in cooperation with the receiver analog circuitry. The receiver analog circuitry and the receiver digital circuitry are partitioned so that interference effects between the receiver analog circuitry and the receiver digital circuitry tend to be reduced.

Abstract: Components of a radio-frequency (RF) apparatus including transceiver circuitry and frequency modification circuitry of a crystal oscillator circuit that generates a reference signal with adjustable frequency may be partitioned in a variety of ways, for example, as one or more separate integrated circuits. The frequency modification circuitry may be implemented as part of a crystal oscillator circuit that includes digitally controlled crystal oscillator (“DCXO”) circuitry and a crystal. The frequency modification circuitry may include at least one variable capacitance device and may be employed to generate a reference signal with adjustable frequency. The adjustable reference signal may be provided to other components of the RF apparatus and/or the RF apparatus may be configured to provide the adjustable reference signal to baseband processor circuitry.