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In analog circuits a high impedance node is one that does not have any low impedance paths to any other nodes in the frequency range being considered.Since the terms low and high depend on context to some extent, it is possible in principle for some high impedance nodes to be described as low impedance in one context, and high impedance in another; so the node (perhaps a signal source or ...
In digital electronics, a tri-state or three-state buffer is a type of digital buffer that has three stable states: a high voltage output state (logical 1), a low output state (logical 0), and a high-impedance (Hi-Z) state.
Generally, a TTL output does not rise high enough to be reliably recognized as a logic 1 by a CMOS input, especially if it is only connected to a high-input-impedance CMOS input that does not source significant current. This problem was solved by the invention of the 74HCT family of devices that uses CMOS technology but TTL input logic levels.
If all inputs are high, each buffer will be in a high-impedance state and the pull-up resistor will pull the output high. But if any input is low, the output will be pulled low by the buffer for that input. This corresponds to wired AND in active-high logic, or to wired OR in active-low logic, and allows multiple inputs to share the same output ...
The difference of principal between CML and ECL as a link technology is the output impedance of the driver stage: the emitter follower of ECL has a low resistance of around 5 Ω whereas CML connects to the drains of the driving transistors, that have a high impedance, and so the impedance of the pull up/down network (typically 50 Ω resistive ...
The Wilson current mirror achieves the high output impedance of equation (6) by negative feedback rather than by emitter degeneration as cascoded mirrors or sources with resistor degeneration do. The node impedance of the only internal node of the mirror, the node at the emitter of Q 3 and the collector of Q 2, is quite low. [3]
A three-state logic gate is a type of logic gate that can have three different outputs: high (H), low (L) and high-impedance (Z). The high-impedance state plays no role in the logic, which is strictly binary. These devices are used on buses of the CPU to allow multiple chips to send data.
HCMOS ("high-speed CMOS") is the set of specifications for electrical ratings and characteristics, forming the 74HC00 family, a part of the 7400 series of integrated circuits. [ 1 ] The 74HC00 family followed, and improved upon, the 74C00 series (which provided an alternative CMOS logic family to the 4000 series but retained the part number ...