Abstract: In one embodiment, a receiver comprises a differential common-gate amplifier having a differential input and a differential output, wherein the differential input comprises a first input and a second input, and the differential common-gate amplifier is configured to amplify an input differential signal at the differential input into an amplified differential signal at the differential output. The receiver also comprises a common-mode voltage sensor configured to sense a common-mode voltage of the input differential signal, a replica circuit configured to generate a replica voltage that tracks a direct current (DC) voltage at at least one of the first and second inputs, and a comparator configured to compare the sensed common-mode voltage with the replica voltage, and to adjust a first bias voltage input to the differential common-gate amplifier based on the comparison, wherein the DC voltage depends on the first bias voltage.

Abstract: An apparatus is provided. The apparatus includes a calibration circuit configured to generate a reference signal and at least one differential circuit each being configured to operate at a calibrated transconductance over process or condition variations based on the reference signal. The calibration circuit may be configured to generate the reference signal independent of the at least one differential circuit. A method for operating at least one differential circuit is provided. The method includes generating a reference signal and operating the at least one differential circuit at a calibrated transconductance or gain over process or condition variations based on the reference signal. The reference signal may be generated independently of the at least one differential circuit.

Abstract: A phase interpolator, including: a pair of load resistors coupled to a supply voltage; a plurality of branches coupled to the pair of load resistors, each branch including a differential pair of transistors connected at source terminal to form a source node; a plurality of tail current sources, each tail current source coupled to one of the source nodes; and a plurality of coupling capacitors, each coupling capacitor coupled between the source nodes in two adjacent branches of the plurality of branches.

Abstract: A stacked integrated circuit includes a first tier IC and a second tier IC. Active faces of the first tier IC and the second tier IC face each other. An interconnect structure, such as microbumps, couples the first tier IC to the second tier IC. An active portion of a voltage regulator is integrated in the first semiconductor IC and coupled to passive components (for example a capacitor or an inductor) embedded in a packaging substrate on which the stacked IC is mounted. The passive components may be multiple through vias in the packaging substrate providing inductance to the active portion of the voltage regulator. The inductance provided to the active portion of the voltage regulator is increased by coupling the through via in the packaging substrate to through vias in a printed circuit board that the packaging substrate is mounted on.

Abstract: In one aspect, a VCO is provided. The VCO includes an inductor, a voltage-controlled capacitive element configured to operate with the inductor to generate an oscillating signal, a voltage supply configured to provide a plurality of voltages to the voltage-controlled capacitive element in a calibration mode, and a control circuit configured to store frequency information indicating frequencies of the oscillating signal in response to the plurality of voltages being provided to the voltage-controlled capacitive element. In another aspect, a PLL is provided. The PLL includes means for selecting, in an open loop configuration, a capacitance of a capacitor based on a target frequency and means for selecting, in a closed loop configuration, an operation voltage of a voltage-controlled capacitive element based on the capacitance of the capacitor.

Abstract: In one embodiment, a receiver comprises a differential common-gate amplifier having a differential input and a differential output, wherein the differential input comprises a first input and a second input, and the differential common-gate amplifier is configured to amplify an input differential signal at the differential input into an amplified differential signal at the differential output. The receiver also comprises a common-mode voltage sensor configured to sense a common-mode voltage of the input differential signal, a replica circuit configured to generate a replica voltage that tracks a direct current (DC) voltage at at least one of the first and second inputs, and a comparator configured to compare the sensed common-mode voltage with the replica voltage, and to adjust a first bias voltage input to the differential common-gate amplifier based on the comparison, wherein the DC voltage depends on the first bias voltage.

Abstract: A gated voltage controlled oscillator has four identically structured delay cells, each of the delay cells having the same output load by connecting to the same number of inputs of other ones of the delay cells. Optionally a four phase sampling clock selects from the delay cell output and samples, at a four phase sampler, an input signal. Optionally an edge detector synchronizes the phase of the gated voltage controlled oscillator to coincide with NRZ bits. Optionally a variable sampling rate selects different phases from the delay cells to selectively sample NRZ bits at a lower rate. Optionally, a pulse width modulation (PWM) mode synchronizes a phase of the sampling clock to sample PWM symbols and recover encoded bits.

Abstract: A driver circuit for transmitting serial data on a communication link combines voltage-mode and current-mode drivers. The driver circuit uses a voltage-mode driver as the main output driver. One or more auxiliary current-mode drivers are connected in parallel with the voltage-mode driver to adjust the output signal by injecting currents into the outputs. The voltage-mode driver supplies most of the output drive. Thus, the output driver circuit can provide the power efficiency benefits associated with voltage-mode drivers. The current-mode drivers can provide, for example, pre-emphasis, level adjustment, skew compensation, and other modifications of the output signals. Thus, the driver circuit can also provide the signal adjustment abilities associated with current-mode drivers.

Abstract: A common mode voltage level shifting circuit including: input nodes configured to receive a differential signal with a first common mode voltage, a pair of shunt capacitors coupled between the input nodes and a corresponding pair of output nodes, a threshold voltage circuit, including the output nodes, coupled to the differential signal though the shunt capacitors, the threshold voltage circuit configured to provide a second common mode voltage for the differential signal at the output nodes, and current sources that are controlled according to a level of the first common mode voltage, the current sources coupled to the output nodes to effect the second common mode voltage.

Abstract: A phase interpolator, including: a pair of load resistors coupled to a supply voltage; a plurality of branches coupled to the pair of load resistors, each branch including a differential pair of transistors connected at source terminal to form a source node; a plurality of tail current sources, each tail current source coupled to one of the source nodes; and a plurality of coupling capacitors, each coupling capacitor coupled between the source nodes in two adjacent branches of the plurality of branches.

Abstract: A phase interpolator, including: a first portion including a first plurality of branches and a plurality of tail current sources, each branch including a differential pair of transistors, source terminals of the differential pair of transistors connect to form a source node, wherein each tail current source couples to one of the source nodes, and wherein the differential pair of transistors and the corresponding tail current source are configured in a current coding scheme; a second portion including a second plurality of branches and a fixed current source coupled to the second plurality of branches, each branch of the second plurality of branches including a second plurality of differential pairs of transistors and a plurality of switches configured in a size coding scheme; wherein the first portion and the second portion are coupled to each other and to a pair of load resistors.

Abstract: A common mode voltage level shifting circuit including: input nodes configured to receive a differential signal with a first common mode voltage, a pair of shunt capacitors coupled between the input nodes and a corresponding pair of output nodes, a threshold voltage circuit, including the output nodes, coupled to the differential signal though the shunt capacitors, the threshold voltage circuit configured to provide a second common mode voltage for the differential signal at the output nodes, and current sources that are controlled according to a level of the first common mode voltage, the current sources coupled to the output nodes to effect the second common mode voltage.

Abstract: Systems and methods for decoding pulse-width modulated (PWM) data are disclosed. An example decoder filters a data input signal with a one-sided pulse filter. The one-sided pulse filter suppresses short pulses on the data input signal and passes long pulses. The example decoder latch the filtered data signal at the end of each bit time of the data input signal. The duration of pulses that are suppressed by the one-sided pulse filter can be calibrated to compensate for circuit variations and to allow the decoder to operate at various data rates. The decoder can be implemented in a small integrated circuit area and can be power efficient.

Abstract: A driver circuit for transmitting serial data on a communication link combines voltage-mode and current-mode drivers. The driver circuit uses a voltage-mode driver as the main output driver. One or more auxiliary current-mode drivers are connected in parallel with the voltage-mode driver to adjust the output signal by injecting currents into the outputs. The voltage-mode driver supplies most of the output drive. Thus, the output driver circuit can provide the power efficiency benefits associated with voltage-mode drivers. The current-mode drivers can provide, for example, pre-emphasis, level adjustment, skew compensation, and other modifications of the output signals. Thus, the driver circuit can also provide the signal adjustment abilities associated with current-mode drivers.

Abstract: Systems and methods for decoding pulse-width modulated (PWM) data are disclosed. An example decoder filters a data input signal with a one-sided pulse filter. The one-sided pulse filter suppresses short pulses on the data input signal and passes long pulses. The example decoder latch the filtered data signal at the end of each bit time of the data input signal. The duration of pulses that are suppressed by the one-sided pulse filter can be calibrated to compensate for circuit variations and to allow the decoder to operate at various data rates. The decoder can be implemented in a small integrated circuit area and can be power efficient.

Abstract: A common mode voltage level shifting circuit including: input nodes configured to receive a differential signal with a first common mode voltage, a pair of shunt capacitors coupled between the input nodes and a corresponding pair of output nodes, a threshold voltage circuit, including the output nodes, coupled to the differential signal though the shunt capacitors, the threshold voltage circuit configured to provide a second common mode voltage for the differential signal at the output nodes, and current sources that are controlled according to a level of the first common mode voltage, the current sources coupled to the output nodes to effect the second common mode voltage.

Abstract: A method includes receiving an input clock signal at a programmable buffer. The method further includes filtering an output signal from the programmable buffer to generate a filtered signal having a voltage level, where the voltage level indicates a duty cycle of the output signal. The method further includes comparing the voltage level to a reference voltage. The method further includes modifying at least one operating parameter of the programmable buffer to adjust the duty cycle of the output signal.

Abstract: A stacked integrated circuit includes a first tier IC and a second tier IC. Active faces of the first tier IC and the second tier IC face each other. An interconnect structure, such as microbumps, couples the first tier IC to the second tier IC. An active portion of a voltage regulator is integrated in the first semiconductor IC and coupled to passive components (for example a capacitor or an inductor) embedded in a packaging substrate on which the stacked IC is mounted. The passive components may be multiple through vias in the packaging substrate providing inductance to the active portion of the voltage regulator. The inductance provided to the active portion of the voltage regulator is increased by coupling the through via in the packaging substrate to through vias in a printed circuit board that the packaging substrate is mounted on.

Abstract: Systems and methods for automatic detection and compensation of frequency offset in point-to-point communication. A burst mode clock and data recovery (CDR) system comprises input data received at a first frequency and a reference clock operating at a second frequency. A master phase-locked loop (PLL) comprising a first gated voltage controlled oscillator (GVCO) is configured to align the phases of reference clock and the input data, and provide phase error information and a recovered clock. A second GVCO is controlled by the recovered clock to sample the input data. A frequency alignment loop comprising a feedback path from the second GVCO to the master PLL is configured to use the phase error information to correct a frequency offset between the first frequency and the second frequency.

Abstract: A stacked integrated circuit includes a first tier IC and a second tier IC. Active faces of the first tier IC and the second tier IC face each other. An interconnect structure, such as microbumps, couples the first tier IC to the second tier IC. An active portion of a voltage regulator is integrated in the first semiconductor IC and coupled to passive components (for example a capacitor or an inductor) embedded in a packaging substrate on which the stacked IC is mounted. The passive components may be multiple through vias in the packaging substrate providing inductance to the active portion of the voltage regulator. The inductance provided to the active portion of the voltage regulator is increased by coupling the through via in the packaging substrate to through vias in a printed circuit board that the packaging substrate is mounted on.