摘要:
Equalization of an incoming data signal can be controlled by sampling that signal at times when data values in that signal should be stable (“data samples”) and when that signal should be in transition between successive data values that are different (“transition samples”). A transition sample that has been taken between two successive differently valued data samples is compared to a reference value (which can be one of those two data samples). The result of this comparison can be used as part of a determination as to whether to increase or decrease equalization of the incoming data signal.
摘要:
Equalization circuitry may be used to compensate for the attenuation of a data signal caused by a transmission medium. The control circuitry for the equalization circuitry may generate control inputs for equalization stages that control the amount of gain provided to the data signal. A comparator may determine whether the gain from the equalization circuitry is less than or more than the desired amount of gain. A programmable up/down counter may adjust the counter value based on the output of the comparator. The counter value may be converted into one or more analog voltages using one or more digital-to-analog converters. These analog voltages may be provided to the equalization stages as control inputs. The control circuitry may also include hysteresis circuitry that prevents the counter value from being adjusted when the gain produced by the equalization stages is close to the desired amount of gain.
摘要:
Equalization of an incoming data signal can be controlled by sampling that signal at times when data values in that signal should be stable (“data samples”) and when that signal should be in transition between successive data values that are different (“transition samples”). A transition sample that has been taken between two successive differently valued data samples is compared to a reference value (which can be one of those two data samples). The result of this comparison can be used as part of a determination as to whether to increase or decrease equalization of the incoming data signal.
摘要:
Equalization of an incoming data signal can be controlled by sampling that signal at times when data values in that signal should be stable (“data samples”) and when that signal should be in transition between successive data values that are different (“transition samples”). A transition sample that has been taken between two successive differently valued data samples is compared to a reference value (which can be one of those two data samples). The result of this comparison can be used as part of a determination as to whether to increase or decrease equalization of the incoming data signal.
摘要:
Systems and methods for adjusting a signal received from a communication path are disclosed. A receiver can receive a signal from a communication path which attenuates at least some frequency components of the signal. The receiver can include an equalization block that adjusts at least some of the frequency content of the received signal, a signal normalization block that provides a normalized signal amplitude and/or a normalized edge slope, and a control block. In one embodiment, the control block controls frequency adjustment in the equalization block for high frequencies. For low frequency adjustment, user-programmable parameters control the normalized signal amplitude in the signal normalization block and the low frequency adjustment in the equalization block.
摘要:
Equalization of an incoming data signal can be controlled by sampling that signal at times when data values in that signal should be stable (“data samples”) and when that signal should be in transition between successive data values that are different (“transition samples”). A transition sample that has been taken between two successive differently valued data samples is compared to a reference value (which can be one of those two data samples). The result of this comparison can be used as part of a determination as to whether to increase or decrease equalization of the incoming data signal.
摘要:
Signal offset variation caused by transistor variation/mismatch in integrated circuits may be reduced. In one embodiment, a buffer circuit has variable-valued circuit elements. Offset variation measurements are made and the variable-valued circuit elements are calibrated to reduce the measured offset variation. In another embodiment, each amplifying stage of a multi-stage buffer provides variable gain. The total DC gain of the cascade is distributed unevenly across the stages, with more DC gain being provided by amplifier stages at the beginning of the cascade than at the end. An additional pre-amplifier stage can also be provided at the beginning of the cascade.
摘要:
Data signals transmitted over transmission media suffer from attenuation caused by the transmission media. Equalization circuitry may be provided to compensate for attenuation caused by the transmission media. Equalization circuitry may include multiple stages arranged in series to allow the frequency responses of the stages to aggregate together. Each stage may be programmable to insert a zero, which causes the frequency response of the stage to increase in magnitude by 20 dB/decade. The frequency location of the zero may also be programmable to allow each stage to contribute a certain amount of gain for a specific frequency. Each stage may also be programmable to determine the location of poles for reduction of high frequency noise and cross-talk cancellation.
摘要:
Data signals transmitted over transmission media suffer from attenuation caused by the transmission media. Equalization circuitry may be provided to compensate for attenuation caused by the transmission media. Equalization circuitry may include multiple stages arranged in series to allow the frequency responses of the stages to aggregate together. Each stage may be programmable to insert a zero, which causes the frequency response of the stage to increase in magnitude by 20 dB/decade. The frequency location of the zero may also be programmable to allow each stage to contribute a certain amount of gain for a specific frequency. Each stage may also be programmable to determine the location of poles for reduction of high frequency noise and cross-talk cancellation.
摘要:
Methods and apparatus are provided for generating a clock signal with relatively high bandwidth and relatively low phase noise. A circuit of the invention can include a pair of transistors serially coupled between a signal of relatively high voltage and a source of relatively low voltage, where a voltage of the signal of relatively high voltage can vary according to a voltage of a variable control signal. A gate of one of the pair of transistors can be coupled to an input clock signal, and an output node between the pair of transistors can be coupled to an output clock signal. The circuit can also include a third transistor, whose drain and source are coupled to the output clock signal, and whose gate can be coupled to a gear input signal. This circuit can advantageously operate under at least two different gears, each with different bandwidth and phase noise characteristics.