The present invention relates to a software-defined radio chip or module suitable for integration on a host device. The software-defined radio chip comprises digital signal processing capability which includes standard digital signal processing hardware and reconfigurable programmable logic, the reconfigurable programmable logic is configured in such a way as to provide secure digital signal processing capability to the software-defined radio, thereby providing a secure software-defined radio.

Radio-frequency (RF) receivers having bandpass sigma-delta analog sigma analog-to-digital converters (ADC) designed to digitize signals in the RF domain are described. Such bandpass ADCs utilize one or more of the following techniques to enhance noise immunity and reduce power consumption: generation of in-phase (I) and quadrature (Q) paths in the digital domain, n.sup.th order resonant bandpass filtering with n>1, and signal sub-sampling in an i.sup.th Nyquist zone with i>1. Compared to RF receivers in which the I and Q paths are generated in the analog domain, these RF receivers exhibit higher IRRs because they are not susceptible to in-phase/quadrature (IQ) mismatch. Using n.sup.th order resonant bandpass filtering with n>1 attenuates unwanted image tones. The bandpass ADC-based RF receivers described herein exhibit enhanced immunity to noise, achieving for example image rejection ratios (IRR) in excess of 95 dB.

An RF receiver includes a low-noise amplifier (LNA) to receive and amplify RF signals, a transformer-based IQ generator circuit, one or more load resisters, one or more mixer circuit, and a downconverter. The transformer-based IQ generator is to generate a differential in-phase local oscillator (LOI) signal and a differential quadrature (LOQ) signal based on a local oscillator (LO) signal received from an LO. The load resisters are coupled to an output of the transformer-based IQ generator. Each of the load resisters is to couple one of the differential LOI and LOQ signals to a predetermined bias voltage. The mixers are coupled to the LNA and the transformer-based IQ generator to receive and mix the RF signals amplified by the LNA with the differential LOI and LOQ signals to generate an in-phase RF (RFI) signal and a quadrature RF (RFQ) signal. The downconverter is to down convert the RFI signal and the RFQ signal into IF signals.

Apparatus and methods remove a voltage offset from an electrical signal, specifically a biomedical signal. A signal is received at a first operational amplifier and is amplified by a gain. An amplitude of the signal is monitored, by a first pair of diode stages coupled to an output of the first operational amplifier, for the voltage offset. The amplitude of the signal is then attenuated by the first pair of diode stages and a plurality of timing banks. The attenuating includes limiting charging, by the first pair of diode stages, of the plurality of timing banks and setting a time constant based on the charging. The attenuating removes the voltage offset persisting at a threshold for a duration of at least the time constant. Saturation of the signal is limited to a saturation recovery time while the saturated signal is gradually pulled into monitoring range over the saturation recovery time.

Apparatus and methods remove a voltage offset from an electrical signal, specifically a biomedical signal. A signal is received at a first operational amplifier and is amplified by a gain. An amplitude of the signal is monitored, by a first pair of diode stages coupled to an output of the first operational amplifier, for the voltage offset. The amplitude of the signal is then attenuated by the first pair of diode stages and a plurality of timing banks. The attenuating includes limiting charging, by the first pair of diode stages, of the plurality of timing banks and setting a time constant based on the charging. The attenuating removes the voltage offset persisting at a threshold for a duration of at least the time constant. Saturation of the signal is limited to a saturation recovery time while the saturated signal is gradually pulled into monitoring range over the saturation recovery time.

A high-frequency signal stimulator system has at least two mutually independent data producers, signal processing and a signal generator. The at least two mutually independent data producers are each configured to produce at least one data packet describing a high-frequency signal to be produced. The signal processing is configured to extract a signal of the data packet produced by the first of the at least two mutually independent data producers and contents of the data packet produced by the second of the at least two mutually independent data producers. The signal generator is configured to produce a high-frequency signal based on the extracted contents.

A multi-channel, multi-band system for wireless communication includes a radio frequency (RF) front end, a mixed-signal front end for converting an incoming analog RF signal into an incoming digital RF signal and converting a composite outgoing digital RF signal into an outgoing analog RF signal, a summation circuit for combining multiple outgoing digital RF signals to the composite outgoing digital RF signal, and multi-band transceivers. Each of the multi-band transceivers may process the incoming digital RF signal to provide an incoming baseband signal and process an outgoing baseband signal to provide an outgoing digital RF signal. The mixed-signal front end may apply a loading control to each transceiver for adjusting an amount of loading on the transmit path from the transceiver to the mixed-signal front-end. The transceivers may individually conduct a feedback calibration on the receive path to optimize the incoming baseband signal for each band.

Apparatus and methods remove a voltage offset from an electrical signal, specifically a biomedical signal. A signal is received at a first operational amplifier and is amplified by a gain. An amplitude of the signal is monitored, by a first pair of diode stages coupled to an output of the first operational amplifier, for the voltage offset. The amplitude of the signal is then attenuated by the first pair of diode stages and a plurality of timing banks. The attenuating includes limiting charging, by the first pair of diode stages, of the plurality of timing banks and setting a time constant based on the charging. The attenuating removes the voltage offset persisting at a threshold for a duration of at least the time constant. Saturation of the signal is limited to a saturation recovery time while the saturated signal is gradually pulled into monitoring range over the saturation recovery time.

Apparatus and methods remove a voltage offset from an electrical signal, specifically a biomedical signal. A signal is received at a first operational amplifier and is amplified by a gain. An amplitude of the signal is monitored, by a first pair of diode stages coupled to an output of the first operational amplifier, for the voltage offset. The amplitude of the signal is then attenuated by the first pair of diode stages and a plurality of timing banks. The attenuating includes limiting charging, by the first pair of diode stages, of the plurality of timing banks and setting a time constant based on the charging. The attenuating removes the voltage offset persisting at a threshold for a duration of at least the time constant. Saturation of the signal is limited to a saturation recovery time while the saturated signal is gradually pulled into monitoring range over the saturation recovery time.

A multi-channel, multi-band system for wireless communication includes a radio frequency (RF) front end, a mixed-signal front end for converting an incoming analog RF signal into an incoming digital RF signal and converting a composite outgoing digital RF signal into an outgoing analog RF signal, a summation circuit for combining multiple outgoing digital RF signals to the composite outgoing digital RF signal, and multi-band transceivers. Each of the multi-band transceivers may process the incoming digital RF signal to provide an incoming baseband signal and process an outgoing baseband signal to provide an outgoing digital RF signal. The mixed-signal front end may apply a loading control to each transceiver for adjusting an amount of loading on the transmit path from the transceiver to the mixed-signal front-end. The transceivers may individually conduct a feedback calibration on the receive path to optimize the incoming baseband signal for each band.