Abstract: In an example, a system includes a phase frequency detector (PFD) coupled to a charge pump, and a loop filter coupled to the charge pump. The system also includes a voltage controlled oscillator (VCO) coupled to the loop filter. The system includes a fast Fourier transform (FFT) engine coupled to an output of the VCO, the FFT engine configured to estimate a phase and a magnitude of reference spurs of an input reference signal. The system includes spur correction circuitry coupled to an input of the VCO, the spur correction circuitry configured to correct for the reference spurs of the input reference signal based at least in part on the phase and magnitude of the reference spurs.

Abstract: An example system includes: interleaving circuitry including a data input, a plurality of data outputs, and a plurality of clock inputs, the data input coupled to the received data input and each of the plurality of clock inputs coupled to one of the plurality of receiver clock outputs; and handoff circuitry coupled to the interleaving circuitry, the handoff circuitry including: comparison circuitry coupled to the clock generation circuitry and configured to compare the plurality of receiver clocks to the transmission clock; clock configuration circuitry coupled to the comparison circuitry and configured to select one of the plurality of receiver clocks based on the comparison circuitry; and a plurality of flip-flops coupled to the clock configuration circuitry and configured to convert the plurality of data outputs from the plurality of receiver clocks to the transmission clock to generate a plurality of transmission data streams based on the one of the plurality of receiver clocks selected by the clock conf

Abstract: An example system includes: interleaving circuitry including a data input, a plurality of data outputs, and a plurality of clock inputs, the data input coupled to the received data input and each of the plurality of clock inputs coupled to one of the plurality of receiver clock outputs; and handoff circuitry coupled to the interleaving circuitry, the handoff circuitry including: comparison circuitry coupled to the clock generation circuitry and configured to compare the plurality of receiver clocks to the transmission clock; clock configuration circuitry coupled to the comparison circuitry and configured to select one of the plurality of receiver clocks based on the comparison circuitry; and a plurality of flip-flops coupled to the clock configuration circuitry and configured to convert the plurality of data outputs from the plurality of receiver clocks to the transmission clock to generate a plurality of transmission data streams based on the one of the plurality of receiver clocks selected by the clock conf

Abstract: A low noise amplifier for an RF sampling analog front end. The amplifier includes digital step attenuation for applying a selected attenuation to signals received at an input node, and a gain stage coupled to amplify the attenuated signal from the digital step attenuation circuit. In a differential amplifier implementation, a first input capacitor is coupled between a positive side input node and an output of the negative side digital attenuation circuit, and a second input capacitor is coupled between a negative side input node and an output of the positive side digital step attenuation circuit. In some embodiments, variable feedback circuits are coupled between each input node and an output of the corresponding gain stage, to selectively apply active termination at the input at high gain settings of the amplifier. Variable input and output resistors, and programmable noise filtering at the output, are provided in some embodiments.

Abstract: In described examples, a retimer includes a reference voltage generator, first, second, third, and fourth comparators, a hit sensor, a window results comparison circuit, and a window control circuit. First inputs of the first, second, third, and fourth comparators receive samples of a data stream. First, second, third, and fourth outputs of the reference voltage generator are coupled to respective second inputs of the first, second, third, and fourth comparators. The third and fourth comparators output to, respectively, first and second inputs of the hit sensor. The hit sensor outputs to an input of the window results comparison circuit. The window results comparison circuit outputs to an input of the window control circuit. The window control circuit outputs to an input of the reference voltage generator.

Abstract: In described examples, a circuit includes a calibration engine. The calibration engine generates multiple input codes. A digital to analog converter (DAC) is coupled to the calibration engine, and generates a first calibration signal in response to a first input code of the multiple input codes. An analog to digital converter (ADC) is coupled to the DAC, and generates multiple raw codes responsive to the first calibration signal. A storage circuit is coupled to the ADC and stores a first output code corresponding to the first input code. The first output code is obtained using the multiple raw codes generated by the ADC.

Abstract: A signal transmission system includes an equalization filter configured to filter an input signal based at least in part on a feedback signal, a slicer configured to generate data based on the filtered input signal at a plurality of different phases, a synchronizer configured to compute a phase delay between the input signal at each of the different phases and the data, and a pattern generator configured to generate the feedback signal at a phase adjusted by the phase delay.

Abstract: A spur correction system for a transmit chain having an interleaving multiplexer. In some embodiments, the spur correction system includes a spur sense chain, a correction controller, and a Q path corrector. The interleaving multiplexer combines signals from multiple bands in response to a clock signal. The spur sense chain estimates an error that is in phase with the clock signal (an I-phase error) and an error that is a derivative of the clock signal (a Q-phase error). The correction controller compensates for the estimated I-phase error by injecting an I-phase correction signal into the transmit chain. The Q path corrector compensates for the estimated Q-phase error by selectively connecting one or more capacitors within the interleaving multiplexer.

Abstract: In described examples, a charge pump includes an output, first and second transistors, a control circuit, a multiplexer, and a calibration circuit. The first transistor's drain is coupled to the output. The second transistor's drain is part of a current path separate from a current path that includes the first transistor's drain. The control circuit generates a control signal in response to voltages at the gates of the first and second transistors. First and second inputs of the multiplexer are respectively coupled to sources of the first and second transistors. A control input of the multiplexer is coupled to receive the control signal. A first input of the calibration circuit is coupled to an output of the multiplexer. A second input of the calibration circuit receives a reference voltage. First and second outputs of the calibration circuit are respectively coupled to body terminals of the first and second transistors.

Abstract: Techniques maintaining receiver reliability, including determining a present attenuation level for an attenuator, wherein the attenuation level is set by a gain controller, determining a relative reliability threshold based on the present attenuation level, receiving a radio frequency (RF) signal, determining a voltage level of the received RF signal, comparing the voltage level of the received RF signal to the relative reliability threshold to determine that a reliability condition exists, and overriding, in response to the determination that the reliability condition exists, the present attenuation level set by the gain controller with an override attenuation level based on the present attenuation level.

Abstract: A signal transmission system includes an equalization filter configured to filter an input signal based at least in part on a feedback signal, a slicer configured to generate data based on the filtered input signal at a plurality of different phases, a synchronizer configured to compute a phase delay between the input signal at each of the different phases and the data, and a pattern generator configured to generate the feedback signal at a phase adjusted by the phase delay.

Abstract: A low noise amplifier for an RF sampling analog front end. The amplifier includes digital step attenuation for applying a selected attenuation to signals received at an input node, and a gain stage coupled to amplify the attenuated signal from the digital step attenuation circuit. In a differential amplifier implementation, a first input capacitor is coupled between a positive side input node and an output of the negative side digital attenuation circuit, and a second input capacitor is coupled between a negative side input node and an output of the positive side digital step attenuation circuit. In some embodiments, variable feedback circuits are coupled between each input node and an output of the corresponding gain stage, to selectively apply active termination at the input at high gain settings of the amplifier. Variable input and output resistors, and programmable noise filtering at the output, are provided in some embodiments.

Abstract: A receiver circuit comprising an equalizer and a method of correcting offset in the equalizer. In an example, the equalizer includes a plurality of delay stages for sampling and storing a sequence input samples, and a plurality of coefficient gain stages, each coupled to a corresponding delay stage to apply a gain corresponding to a coefficient value. The outputs of the coefficient gain stages are summed to produce a weighted sum for quantization by a slicer. Offset correction circuitry is provided, including memory storing a look-up table (LUT) for each coefficient gain stage, each storing offset correction values corresponding to the available coefficient values for the coefficient gain stage. Addressing circuitry retrieves the offset correction values for the coefficient values currently selected for each gain stage, and applies an offset correction corresponding to the sum of the retrieved offset correction values.

Abstract: A voltage-to-delay converter converts input signals into delay signals, and includes: a first stage for receiving the input signals and for generating intermediate output signals, wherein timing of the intermediate output signals corresponds to voltages of the input signals, and wherein the first stage has a voltage source for providing a rail-to-rail voltage; and a second stage for receiving the intermediate output signals and for generating rail-to-rail output signals, wherein timing of the rail-to-rail output signals corresponds to the timing of the intermediate output signals, and wherein voltage of the rail-to-rail output signals corresponds to the rail-to-rail voltage. A voltage-to-delay converter block is also described. A circuit for receiving differential input signals, generating corresponding output signals, and removing common mode signals from the output signals is also described.

Abstract: A first logic gate has a first input coupled to a first circuit input or a second circuit input, a second input selectively coupled to a third circuit input or a fourth circuit input, and a first output. The first output has a signal with a duty cycle that is a function of a phase difference between a first signal on the first input and a second signal on the second input. A second logic gate has a third input coupled to the third circuit input or the fourth circuit input, a fourth input coupled to the second circuit input or the fourth circuit input, and a second output. The second output has a signal with a duty cycle that is a function of a phase difference between a third signal on the third input and a fourth signal on the fourth input.

Abstract: In described examples, a circuit includes a calibration engine. The calibration engine generates multiple input codes. A digital to analog converter (DAC) is coupled to the calibration engine, and generates a first calibration signal in response to a first input code of the multiple input codes. An analog to digital converter (ADC) is coupled to the DAC, and generates multiple raw codes responsive to the first calibration signal. A storage circuit is coupled to the ADC and stores a first output code corresponding to the first input code. The first output code is obtained using the multiple raw codes generated by the ADC.

Abstract: A spur correction system for a transmit chain having an interleaving multiplexer. In some embodiments, the spur correction system includes a spur sense chain, a correction controller, and a Q path corrector. The interleaving multiplexer combines signals from multiple bands in response to a clock signal. The spur sense chain estimates an error that is in phase with the clock signal (an I-phase error) and an error that is a derivative of the clock signal (a Q-phase error). The correction controller compensates for the estimated I-phase error by injecting an I-phase correction signal into the transmit chain. The Q path corrector compensates for the estimated Q-phase error by selectively connecting one or more capacitors within the interleaving multiplexer.

Abstract: A system includes a Zero IF transmitter having a mixer and a programmable gain stage. The Zero IF transmitter also includes an intermediate stage between the mixer and the programmable gain stage, wherein the intermediate stage is configured to decouple the mixer and the programmable gain stage.

Abstract: A first logic gate has a first input coupled to a first circuit input or a second circuit input, a second input selectively coupled to a third circuit input or a fourth circuit input, and a first output. The first output has a signal with a duty cycle that is a function of a phase difference between a first signal on the first input and a second signal on the second input. A second logic gate has a third input coupled to the third circuit input or the fourth circuit input, a fourth input coupled to the second circuit input or the fourth circuit input, and a second output. The second output has a signal with a duty cycle that is a function of a phase difference between a third signal on the third input and a fourth signal on the fourth input.

Abstract: Techniques maintaining receiver reliability, including determining a present attenuation level for an attenuator, wherein the attenuation level is set by a gain controller, determining a relative reliability threshold based on the present attenuation level, receiving a radio frequency (RF) signal, determining a voltage level of the received RF signal, comparing the voltage level of the received RF signal to the relative reliability threshold to determine that a reliability condition exists, and overriding, in response to the determination that the reliability condition exists, the present attenuation level set by the gain controller with an override attenuation level based on the present attenuation level.