摘要:
A PLL circuit and method provides an adjustable operating frequency range by using at least two VCOs. In an embodiment of the present invention, circuit components of a PLL are adjusted in order to obtain a selected frequency range. In particular, a gain of a charge pump and resistance of a filter is adjusted responsive to a control signal. In alternate embodiments of the present invention, a voltage regulator, including an operational amplifier, is coupled to the output of the filter and the respective inputs of two VCOs. An output multiplexer then selects a VCO output responsive to the control signal. In another embodiment of the present invention, a multiplexer is coupled to the output of the voltage regulator to select which VCO receives a buffered voltage. In another embodiment of the present invention, respective operational amplifiers that may be enabled or disabled responsive to the control signal are coupled to a filter output and respective VCO inputs in order to provide an adjustable frequency range.
摘要:
An apparatus is described having a feedback loop. The feedback loop has an output that approaches a steady state as a data line voltage approaches a reference voltage. The apparatus also includes a driving transistor that drives the data line. The driving transistor has an output impedance that is controlled by the feedback loop output, the feedback loop output keeps the driving transistor output impedance within a high output impedance region when the feedback loop output reaches the steady state.
摘要:
An integrated circuit device includes a receiver, a register and a clock circuit. The receiver samples data from an external signal line in response to an internal clock signal. The register stores a value that represents a timing offset to adjust the time at which the data is sampled. The clock circuit generates the internal clock signal such that the internal clock signal maintains a controlled timing relationship with respect to an external clock signal. The clock circuit includes an interpolator that phase mixes a set of reference clock signals such that the internal clock signal is phase offset in accordance with the value.
摘要:
An improved, open-loop push-pull driver is described. Closed-loop feedback loop techniques for control of the push-pull driver are described. These techniques are particularly well adapted to control shoot-through current in a push-pull driver circuit.
摘要:
A method and apparatus for an adjustable phase interpolator is provided. The adjustable phase interpolator includes a phase interpolator circuit that has a voltage input and a voltage output. The adjustable phase interpolator further includes a controllable capacitive load coupled to either the input or the output of the phase interpolator circuit. The controllable capacitive load is designed to add or subtract capacitance to the adjustable phase interpolator.
摘要:
An integrated circuit device includes a transmitter circuit operable to transmit a timing signal over a first wire to a DRAM. The DRAM receives a first signal having a balanced number of logical zero-to-one transitions and one-to-zero transitions and samples the first signal at a rising edge of the timing signal to produce a respective sampled value. The device further includes a receiver circuit to receive the respective sampled value from the DRAM over a plurality of wires separate from the first wire. In a first mode, the transmitter circuit repeatedly transmits incrementally offset versions of the timing signal to the DRAM until sampled values received from the DRAM change from a logical zero to a logical one or vice versa; and in a second mode, it transmits write data over the plurality of wires to the DRAM according to a write timing offset generated based on the sampled values.
摘要:
A system includes a first integrated circuit device and a second integrated circuit device. The first device transmits a data sequence to the second integrated circuit device, and the second device samples the data sequence to produce receiver data. The second device then transmits the receiver data back to the first device. Within the first integrated circuit device, a comparison between the data sequence and the receiver data is performed, and based on the comparison, the first device generates information representative of a calibrated timing offset. The first device uses the information representative of the calibrated timing offset to adjust timing associated with transferring write data from the first integrated circuit to the second integrated circuit.
摘要:
Described are methods and systems for distributing low-skew, predictably timed clock signals. A clock distribution network includes a plurality of dynamically adjustable clock buffers. A control circuit connected to each clock buffer controls the delays through the clock buffers in response to process, voltage, and temperature variations, and consequently maintains a relatively constant signal-propagation delay through the network. In one embodiment, each clock buffer includes skew-offset circuitry that adds to or subtracts from the PVT compensated delay values provided by the PVT control circuit to simplify clock skew minimization.
摘要:
An improved, open-loop push-pull driver is described. Closed-loop feedback loop techniques for control of the push-pull driver are described. These techniques are particularly well adapted to control shoot-through current in a push-pull driver circuit.
摘要:
A circuit and method for level-shifting an input signal are disclosed that provide for level-shifting of a the input signal where an external voltage level is greater than an internal voltage of the signal. In the present invention, the input signal is compared to a reference signal to produce a differential current signal reflecting the logic level of the input signal. The differential current signal is reflected through a pair of current mirrors operating from the external voltage level to drive a pair of resistive loads. Each of the resistive loads is coupled in series with a current sink between the internal supply voltage and a ground voltage. As a result, the input signal may be received and level-shifted with gain even when the internal supply voltage is less than twice a transistor threshold voltage without introducing significant distortion to the received signal.