What are disadvantages of Wilson current mirror?

What are disadvantages of Wilson current mirror?

Limitations of Wilson Current Mirror: It has a higher compliance voltage compared with the basic two transistor current mirror circuit. Wilson current mirror circuit creates noise across the output. This is due to the feedback which raises output impedance and directly affect the collector current.

What is the advantage of using Wilson current mirror?

A Wilson current mirror or Wilson current source, named after George Wilson, is an improved mirror circuit configuration designed to provide a more constant current source or sink. It provides a much more accurate input to output current gain. The structure is shown in figure 11.9.

How does Wilson current mirror work?

A Wilson current mirror is a three-terminal circuit (Fig. 1) that accepts an input current at the input terminal and provides a “mirrored” current source or sink output at the output terminal. The mirrored current is a precise copy of the input current.

What is the use of Widlar current source?

The Widlar circuit may be used with bipolar transistors, MOS transistors, and even vacuum tubes. An example application is the 741 operational amplifier, and Widlar used the circuit as a part in many designs. This circuit is named after its inventor, Bob Widlar, and was patented in 1967.

Why is Wilson current mirror better than simple current mirror?

Now wilson current mirror is less dependent on beta values meaning it is less dependent on transistor parameters but one of the important advantage of wilson current mirror over other current mirror is that it provides high output impedance which improves the efficiency of the current mirror.

What is the advantage of Widlar current source over basic BJT current source?

It allows you to generate a low output current without using high value resistors.

What is desirable for a current mirror?

Current Transfer Ratio A current mirror circuit is used to copy one active device’s input current to the output of other active devices. This kind of circuit is also known as an ideal current amplifier including the inverting design that can overturn the direction of current flow.

What is current mirror used for?

The current mirror is used to provide bias currents and active loads to circuits. It can also be used to model a more realistic current source (since ideal current sources don’t exist). The circuit topology covered here is one that appears in many monolithic ICs.

Why current mirror is used in differential amplifier?

Current mirror as differential amplifier T3 acts as a regulating valve which increases the current through the current mirror as Input A gets more power while T4 kind of does the opposite by draining current from the mirror with increasing input B power.

How Widlar current source is a good power supply sensitivity?

Supply sensitivity For a simple Widlar current source (Fig. 1) the sensitivity is approximately 0.5 [1]; thus the same 10% variation of power-supply results only in a 5% change of output current. This improvement can be taken even further with the threshold referenced current source.

Which type of feedback is used in Wilson current mirror?

This is a series constant-current keeping feedback (an emitter degeneration). Only, it is negligible for keeping the constant current because the active diode behaves as a voltage-stable element (significant current variations cause insignificant voltage changes).

What is current mirror in op amp?

Op-amp current mirror. Current mirrors have relatively high, sometimes nonlinear input impedance, so they must be fed by a current from a high-impedance current source (sometimes known as a stiff current source). An op amp is required if the input current must have a low-impedance sink.

Why current mirror is used?

How do you calculate current mirror?

This is the function of the current mirror circuit: to regulate current through the load resistor by conveniently adjusting the value of Rbias. Current through the diode is described by a simple equation: power supply voltage minus diode voltage (almost a constant value), divided by the resistance of Rbias.

What is the point of current mirror?

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.

What is the need of current mirror circuit?

A current mirror circuit is used to copy one active device’s input current to the output of other active devices. This kind of circuit is also known as an ideal current amplifier including the inverting design that can overturn the direction of current flow.

What are the disadvantages of basic current mirror?

Drawbacks of Basic current mirror In Basic CM , we have neglected channel modulation. CLM effects result in significant error. ∴ to suppress effect of CLM, cascode CM is used.

Where is current mirror circuit used?

What is a Wilson mirror circuit?

A Wilson current mirror is a three-terminal circuit (Fig. 1) that accepts an input current at the input terminal and provides a “mirrored” current source or sink output at the output terminal. The mirrored current is a precise copy of the input current.

What is the difference between Widlar and Wilson circuits?

The Widlar and Wilson circuits are usually called current “mirrors”. The Widlar mirror is the simpler of the two, shown below. Its transfer function, which is the current gain, is approximately alpha of the BJT.

What is the output impedance of a Wilson current mirror?

The Wilson current mirror has an output impedance that is higher by the factor , on the order of 50X. The input impedance of a current mirror is the ratio of the change in input voltage (the potential from the input terminal to ground in Figures 1 and 2) to the change in input current that causes it.

What is the difference between Wilson current source and current mirror?

Each has different advantages and their uses are for different purposes. So it is hard to say which is better. Wilson is an accurate current mirror; so if you are designing an exact replica of a reference current, you use a Wilson current source.