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Fig. 1: Wilson current mirror Fig. 2: Wilson current source. There are three principal metrics of how well a current mirror will perform as part of a larger circuit. The first measure is the static error, i.e., the difference between the input and output currents expressed as a fraction of the input current.
A current mirror is a circuit designed to copy a current through one active device by controlling the current in another active device of a circuit, keeping the output current constant regardless of loading. The current being "copied" can be, and sometimes is, a varying signal current.
Mathematically the term within the trace is known as the holonomy, which describes a mapping of the fiber into itself upon horizontal lift along a closed loop. The set of all holonomies itself forms a group, which for principal bundles must be a subgroup of the gauge group.
Wilson was a lucky man; in the early 60's, he "killed two birds with one stone" - adding only one transistor to the humble current mirror, he managed to remove the both imperfections of the simple BJT current mirror!
A Widlar current source is a modification of the basic two-transistor current mirror that incorporates an emitter degeneration resistor for only the output transistor, enabling the current source to generate low currents using only moderate resistor values.
In MOSFET technology especially, cascoding can be used in current mirrors to increase the output impedance of the output current source. A modified version of the cascode can also be used as a modulator, particularly for amplitude modulation. The upper device supplies the audio signal, and the lower is the RF amplifier device. High-voltage stack
The linking number is chiral: taking the mirror image of link negates the linking number. The convention for positive linking number is based on a right-hand rule . The winding number of an oriented curve in the x - y plane is equal to its linking number with the z -axis (thinking of the z -axis as a closed curve in the 3-sphere ).
It is the topology of this space (modulo trivial bands) from which the "topology" in topological insulators arises. [ 7 ] Specifically, the number of connected components of the space indicates how many different "islands" of insulators exist amongst the metallic states.