摘要:
Methods and apparatus for delaying a clock signal for a multiple-data-rate interface. An apparatus provides an integrated circuit including a frequency divider configured to receive a first clock signal and a first variable-delay block configured to receive an output from the frequency divider. Also included is a phase detector configured to receive the first clock signal and an output from the first variable-delay block, and an up/down counter configured to receive an output from the phase detector. A second variable-delay block is configured to receive a second clock signal and a plurality of flip-flops are configured to receive an output from the second variable-delay block. The first variable-delay block and the second variable-delay block are configured to receive an output from the up/down counter.
摘要:
Methods and apparatus for delaying a clock signal for a multiple-data-rate interface. An apparatus provides an integrated circuit including a frequency divider configured to receive a first clock signal and a first variable-delay block configured to receive an output from the frequency divider. Also included is a phase detector configured to receive the first clock signal and an output from the first variable-delay block, and an up/down counter configured to receive an output from the phase detector. A second variable-delay block is configured to receive a second clock signal and a plurality of flip-flops are configured to receive an output from the second variable-delay block. The first variable-delay block and the second variable-delay block are configured to receive an output from the up/down counter.
摘要:
An input buffer circuit has a plurality of selectively enabled differential amplifier circuits, where each differential amplifier is configured for compatibility with a particular differential I/O standard and its corresponding input operating range. For example, the input buffer may have two differential amplifiers suitable for receiving LVDS differential input signals over a wide input operating range, and another differential amplifier suitable for receiving the PCML differential input signals. One or more control signals are provided to the input buffer, e.g., programmably, to selectively enable the required differential amplifier(s) for a given I/O standard.
摘要:
An input buffer circuit has a plurality of selectively enabled differential amplifier circuits, where each differential amplifier is configured for compatibility with a particular differential I/O standard and its corresponding input operating range. For example, the input buffer may have two differential amplifiers suitable for receiving LVDS differential input signals over a wide input operating range, and another differential amplifier suitable for receiving the PCML differential input signals. One or more control signals are provided to the input buffer, e.g., programmably, to selectively enable the required differential amplifier(s) for a given I/O standard.
摘要:
A switch circuit selectively provides a reference voltage, needed in some I/O standards, to a logic device. The circuit receives a dedicated power supply that is different from the device's I/O supply. It may also include a level shifting circuit for converting a master control signal having a logic level determined by a first supply to a first control signal having a logic level determined by the dedicated supply. The switch circuit also includes a transmission switch that passes the reference voltage to an output in response to at least the first control signal. The transmission switch may be a CMOS transmission gate with at least one NMOS transistor controlled by the first control signal in parallel with at least one PMOS transistor controlled by a second control signal, complementary to the first. The second control signal may be generated by another level shifting circuit and have a logic level determined by the I/O supply.
摘要:
The present invention encompasses a bus hold and weak pull-up circuit. A resistor having a first node and a second node is coupled to a bi-directional I/O pin at the first node. The weak pull-up circuit is directly coupled to the resistor at the first node. The bus hold circuit is coupled to the resistor at the second node.
摘要:
A supply voltage detection circuit determines when the voltage for any one of the power supply signals received by an integrated circuit device is below its steady state level, as may occur during a hot socket condition when the device is inserted in or removed from a powered-on system. A first detection circuit determines when the first supply voltage level is below its steady state level, and a second detection circuit determines when the second supply voltage level is below its steady state level. A logic circuit provides a detected condition signal that disables current flow through an input/output terminal associated with the supply voltage detection circuit. The circuit is able to rapidly detect hot socket conditions for a wide range of power supply signal levels, including low supply signal levels, while limiting leakage current effects.
摘要:
A supply voltage detection circuit determines when the voltage for any one of the power supply signals received by an integrated circuit device is below its steady state level, as may occur during a hot socket condition when the device is inserted in or removed from a powered-on system. A first detection circuit determines when the first supply voltage level is below its steady state level, and a second detection circuit determines when the second supply voltage level is below its steady state level. A logic circuit provides a detected condition signal that disables current flow through an input/output terminal associated with the supply voltage detection circuit. The circuit is able to rapidly detect hot socket conditions for a wide range of power supply signal levels, including low supply signal levels, while limiting leakage current effects.
摘要:
A Schmitt trigger circuit has an adjustable hysteresis characteristic by providing a plurality of feedback circuits that differently affect at least one, and preferably both, of the circuit's upper trip point level and lower trip point level. The upper trip point level can be adjusted by selecting a desired feedback circuit from a first set of feedback circuits, and/or the lower trip point level can be adjusted by selecting a desired feedback circuit from a second set of feedback circuits. Feedback circuit selection is achieved by one or more control signals that may be programmable. The hysteresis characteristic can be adjusted to meet desired noise margin, delay, and input recognition criteria at different VCC levels. The Schmitt trigger circuit may be a CMOS Schmitt trigger with two input stage NMOS, two input stage PMOS transistors, a first set of NMOS feedback circuits, and a second set of PMOS feedback circuits.
摘要:
An input buffer circuit has a plurality of selectively enabled differential amplifier circuits, where each differential amplifier is configured for compatibility with a particular differential I/O standard and its corresponding input operating range. For example, the input buffer may have two differential amplifiers suitable for receiving LVDS differential input signals over a wide input operating range, and another differential amplifier suitable for receiving the PCML differential input signals. One or more control signals are provided to the input buffer, e.g., programmably, to selectively enable the required differential amplifier(s) for a given I/O standard.