Abstract: Described herein are a method and apparatus for a selective SYSREF (SYStem REFerence signal) scheme that is driven by an external SYSREF source for a system that may include, for example, analog blocks, such as analog-to-digital converters (ADCs), digital-to-analog converters (DACs), radio frequency (RF) arrays, as well as digital blocks, which may include JESD serializer/deserializer (SERDES) Transport and Link Layer circuitry, all of which can be operating at different clock frequencies. In one aspect, synchronization of the components is achieved when an internal SYSREF for the analog blocks is keyed off the external SYSREF, but the internal SYSREF pulse used by the digital blocks is programmatically keyed off one of the periodic internal SYSREF pulses. Additionally, a mechanism is provided for synchronization of the programmatically selected internal SYSREF across different clock domains in the digital blocks.

Abstract: A system and method for digital receiver linearization is provided. An input digital signal is accepted with a plurality of spectral components. The input digital signal may be either a radio frequency (RF) digital signal or a baseband digital signal. Nonlinear distortion is created in response to the input digital signal. As the result of a corrected input digital signal, a primary baseband signal is created with real (I) and imaginary quadrature (Q) components. In response to the nonlinear distortion, auxiliary baseband signals are created with real (IAUX) and imaginary quadrature (QAUX) components. The primary baseband signal is compared to the auxiliary baseband signals to supply complex amplitude correction coefficients. The complex amplitude correction coefficients are used to modify the nonlinear distortion, and the modified nonlinear distortion is subtracted from the input digital signal to supply the corrected input digital signal.

Abstract: A voltage-to-time-to-digital converter (VTDC) and conversion method are provided using a coarse analog-to-digital converter (ADC). A voltage-to-time converter (VTC) receives an analog input voltage-differential signal with a first time duration and supplies an analog first time-differential signal. An ADC receives the input voltage-differential signal and supplies a first digital code representing m bit values. A time-to-digital converter (TDC) receives a second time-differential signal with a second time duration derived from the first time duration. The TDC supplies an output digital code representing p bit values, where p>m. In one aspect the first digital code programs an initial set of TDC residue generators. In another aspect, a dither circuit controls the second time duration in response to a pseudo random signal combined with the first digital code.

Abstract: A multi-symbol per stage pipelined time-to-digital converter (TDC) is presented. The TDC includes a quantizer and a residue generator. The quantizer has an input to accept an analog input first time-differential signal comprising a binary level first edge separated from a binary level second edge by a first duration of time. The first time-differential signal is capable as being represented by m time intervals. The quantizer has an output to supply a first digital code representing Ceil(log2(m)) bit values responsive to (m?1) time interval measurements. The first digital code is a time-to-digital conversion. For example, if the first time-differential signal is capable of being represented as a p-bit binary coded digital word, the quantizer outputs a first digital code representing the Ceil(log2(m)) most significant bit (MSB) values of the p-bit digital word.

Abstract: A sort-and-delay time-to-digital converter (TDC) is provided, made up of a plurality of serially connected sort-and-delay circuits. Each sort-and-delay circuit accepts a time-differential input signal with a first edge separated from a second edge by an input duration of time. The first and second edges are selectively routed as a time-differential output signal with a delayed edge separated from a trailing edge by an output duration of time representing a compression of the input duration of time. Each sort-and-delay circuit also supplies a TDC coded bit (e.g., Gray code) indicating the order in which the first and second edges are routed as leading and trailing edges. The TDC outputs a digital output signal representing the initial input duration of time associated with the initial time-differential input signal received by the initial sort-and-delay circuit. Associated TDC, sort-and-delay, and time amplification methods are also provided.

Abstract: A sort-and-delay time-to-digital converter (TDC) is provided, made up of a plurality of serially connected sort-and-delay circuits. Each sort-and-delay circuit accepts a time-differential input signal with a first edge separated from a second edge by an input duration of time. The first and second edges are selectively routed as a time-differential output signal with a delayed edge separated from a trailing edge by an output duration of time representing a compression of the input duration of time. Each sort-and-delay circuit also supplies a TDC coded bit (e.g., Gray code) indicating the order in which the first and second edges are routed as leading and trailing edges. The TDC outputs a digital output signal representing the initial input duration of time associated with the initial time-differential input signal received by the initial sort-and-delay circuit. Associated TDC, sort-and-delay, and time amplification methods are also provided.

Abstract: A system and method are provided for converting voltage-to-time-to-digital signals. The method periodically samples a continuous analog input and discharges the sampled analog input at a predetermined rate to supply a continuous analog ramp signal. The ramp signal is converted into an n-bit coded digital word representing the q most significant bits (MSBs) of a k-bit binary word, where q is an integer greater than 0, n is an integer greater than 1, and k is an integer greater than q. At least one bit of the coded digital word is supplied at a time representing the p least significant bits (LSBs) of the k-bit binary word. The coded digital word is converted into a single-bit pulse signal containing timing information representing the p LSBs of the k-bit binary word at an output, and the timing information is converted into the p LSBs of the k-bit binary word.

Abstract: A system and method are provided for calibrating timing mismatch in an n-path time interleaved analog-to-digital converter (ADC). The method digitizes an analog signal with an n-path interleaved ADC, creating an interleaved ADC signal. In a first process, the phase of the interleaved ADC signal is rotated by 90 degrees, creating a rotated signal. This rotation may be accomplished using a finite impulse response (FIR) filter with taps at {0.5, 0, ?0.5}, enabled as a derivative filter, or as a Hilbert transformation. In a parallel second process, the interleaved ADC signal is delayed, creating a delayed signal. The rotated signal is multiplied by the delayed signal to create a timing error signal. Using the timing error signal, timing errors are accumulated for the ADC signal paths, and corrections are applied that minimize timing errors in each of the n ADC signal paths.

Abstract: A system and method are provided for calibrating timing mismatch in an n-path time interleaved analog-to-digital converter (ADC). The method digitizes an analog signal with an n-path interleaved ADC, creating an interleaved ADC signal. In a first process, the phase of the interleaved ADC signal is rotated by 90 degrees, creating a rotated signal. This rotation may be accomplished using a finite impulse response (FIR) filter with taps at {0.5, 0, ?0.5}, enabled as a derivative filter, or as a Hilbert transformation. In a parallel second process, the interleaved ADC signal is delayed, creating a delayed signal. The rotated signal is multiplied by the delayed signal to create a timing error signal. Using the timing error signal, timing errors are accumulated for the ADC signal paths, and corrections are applied that minimize timing errors in each of the n ADC signal paths.

Abstract: A current impulse (CI) method is provided for converting digital data signals to analog values. First, digital data hits are converted into current impulses. Then, the current impulses are converted into analog currents representing the digital data hits. More typically, the method accepts a k-bit digital word, and converts the k-bit digital word into (k) corresponding current impulses. In one aspect, the method accepts (n) consecutive k-bit digital words. Then, for each bit position in the k-bit digital word, (n) consecutive bits are sampled using (n) consecutive phases of an n-phase clock, creating (n) interleaved current impulses. The (n) interleaved current impulses are converted into an analog current representing the (n) consecutive k-bit digital words. Alternatively, (n) consecutive hits are sampled using (n) consecutive phases of an n-phase clock for each bit position in the k-bit digital word, creating (n) summed current impulses. A CI digital-to-analog converter is also provided.

Abstract: A current impulse (CI) method is provided for converting digital data signals to analog values. First, digital data bits are converted into current impulses. Then, the current impulses are converted into analog currents representing the digital data bits. More typically, the method accepts a k-bit digital word, and converts the k-bit digital word into (k) corresponding current impulses. In one aspect, the method accepts (n) consecutive k-bit digital words. Then, for each bit position in the k-bit digital word, (n) consecutive bits are sampled using (n) consecutive phases of an n-phase clock, creating (n) interleaved current impulses. The (n) interleaved current impulses are converted into an analog current representing the (n) consecutive k-bit digital words. Alternatively, (n) consecutive bits are sampled using (n) consecutive phases of an n-phase clock for each bit position in the k-bit digital word, creating (n) summed current impulses. A CI digital-to-analog converter is also provided.

Abstract: A Traveling Pulse Wave Quantization method is provided for converting a time sensitive signal to a digital value. A first stop signal is delayed by a first time delay, a first plurality of times, to create a delayed first stop signal. A clock signal is delayed by a second time delay, a first plurality of times, to create a delayed clock signal first period. Each second time delay is associated with a corresponding first time delay, and the second time delay is greater than the first time delay. When the delayed first stop signal occurs before the delayed clock signal first period, a count of the delays is stopped and converted into a digital or thermometer value. An accurate resampled value is provided regardless of the duration in delay between the first stop signal and a second stop signal that is accepted after the first stop signal.

Abstract: A Traveling Pulse Wave Quantization method is provided for converting a time sensitive signal to a digital value. A first stop signal is delayed by a first time delay, a first plurality of times, to create a delayed first stop signal. A clock signal is delayed by a second time delay, a first plurality of times, to create a delayed clock signal first period. Each second time delay is associated with a corresponding first time delay, and the second time delay is greater than the first time delay. When the delayed first stop signal occurs before the delayed clock signal first period, a count of the delays is stopped and converted into a digital or thermometer value. An accurate resampled value is provided regardless of the duration in delay between the first stop signal and a second stop signal that is accepted after the first stop signal.

Abstract: A system and method are provided of performing background corrections for an interleaving analog-to-digital converter (ADC). An analog input signal s1(t) is accepted having a first frequency f1 and a bandwidth (BW). A clock at frequency fs creates n sample clocks with evenly spaced phases, each having a sample clock frequency of fs/2. A first tone signal s2(t) is generated at second frequency f2, outside BW. The analog input signal and the first tone signal are combined, creating a combination signal, which is sampled using the sample clocks, creating n digital sample signals per clock period 1/fs. The n digital sample signals are interleaved, creating an interleaved signal. Corrections are applied that minimize errors in the interleaved signal, to obtain a corrected digital output. Errors are determined at an alias frequency f3, associated with the second frequency f2, to obtain correction information for a rotating pair of digital sample signals.

Abstract: A system and method are provided for measuring current sources, such as might be useful in the calibration of a digital-to-analog converter (DAC). The method provides a first plurality of current sources. Each current source is engageable to supply a current representing a corresponding nominal value. The method selectively enables current source combinations of current. In response to measuring the current source combinations, current difference values are found, and the current source nominal values are adjusted using the current difference values. In one aspect, a reference current source is provided having a reference first value, and the current source nominal values are adjusted with respect to the reference first value. The current sources may have corresponding nominal digital values adjusted using measured digital difference values.

Abstract: A system and method are provided of performing background corrections for an interleaving analog-to-digital converter (ADC). An analog input signal s1(t) is accepted having a first frequency f1 and a bandwidth (BW). A clock at frequency fs creates n sample clocks with evenly spaced phases, each having a sample clock frequency of fs/2. A first tone signal s2(t) is generated at second frequency f2, outside BW. The analog input signal and the first tone signal are combined, creating a combination signal, which is sampled using the sample clocks, creating n digital sample signals per clock period 1/fs. The n digital sample signals are interleaved, creating an interleaved signal. Corrections are applied that minimize errors in the interleaved signal, to obtain a corrected digital output. Errors are determined at an alias frequency f3, associated with the second frequency f2, to obtain correction information for a rotating pair of digital sample signals.

Abstract: A charge canceling multiplying digital-to-analog converter (MDAC) is provided with a reference block having inputs to accept reference voltages each sample clock cycle. The MDAC includes a sampling block having inputs to accept differential analog input voltage signals each sample clock cycle. A differential amplifier has a negative input and positive input connected to the reference block and sampling block to receive differential amplifier input signals, and a positive output and a negative output to supply differential output voltage signals each amplify clock cycle. The sampling section includes a first pair of feedback capacitors connected between the differential amplifier negative input and positive output, and a second pair of feedback capacitors connected between the differential amplifier positive input and negative output each amplify clock cycle. A capacitor from the first pair of parallel feedback capacitors is swapped with a capacitor from the second pair prior to each sample clock cycle.

Abstract: A system and method are provided for frequency multiplication jitter correction. The method accepts an analog reference signal having a first frequency, and using the analog reference signal, derives a system clock signal having a second frequency, greater than the first frequency. A PLL using a voltage controlled oscillator (VCO) is one example of a frequency multiplier. The method samples the amplitude of the analog reference signal using the system clock signal and converts the sampled analog reference signal into a digitized reference signal. In response to comparing the digitized reference signal to an ideal digitized reference signal, the phase error correction for the system clock signal is derived. The phase error correction at a first instance of time can be applied to the digitized data signal, previously converted from an analog data signal sampled at a first instance of time with the system clock signal.

Abstract: A system and method are provided for frequency multiplication jitter correction. The method accepts an analog reference signal having a first frequency, and using the analog reference signal, derives a system clock signal having a second frequency, greater than the first frequency. A PLL using a voltage controlled oscillator (VCO) is one example of a frequency multiplier. The method samples the amplitude of the analog reference signal using the system clock signal and converts the sampled analog reference signal into a digitized reference signal. In response to comparing the digitized reference signal to an ideal digitized reference signal, the phase error correction for the system clock signal is derived. The phase error correction at a first instance of time can be applied to the digitized data signal, previously converted from an analog data signal sampled at a first instance of time with the system clock signal.

Abstract: A system and method are provided for frequency multiplication jitter correction. The method accepts an analog reference signal having a first frequency, and using the analog reference signal, derives a system clock signal having a second frequency, greater than the first frequency. A PLL using a voltage controlled oscillator (VCO) is one example of a frequency multiplier. The method samples the amplitude of the analog reference signal using the system clock signal and converts the sampled analog reference signal into a digitized reference signal. In response to comparing the digitized reference signal to an ideal digitized reference signal, the phase error correction for the system clock signal is derived. The phase error correction at a first instance of time can be applied to the digitized data signal, previously converted from an analog data signal sampled at a first instance of time with the system clock signal.