What Is a Current Source?

The internal resistance of the current source is relatively large relative to the load impedance, and the fluctuation of the load impedance will not change the current magnitude. The series resistance in the current source circuit is meaningless because it does not change the load current or the voltage across the load. This type of resistor should be simplified on the schematic. The load impedance only makes sense if it is connected in parallel to the current source, and it is a shunt relationship with the internal resistance.

1. The output current is constant;

2. DC equivalent resistance is infinite;

3. The AC equivalent resistance is infinite.

The current source, that is, the ideal current source, is a model abstracted from the actual power source. The end button can always provide a certain current to the outside regardless of the voltage across it. The current source has two basic properties: , The current it provides is a fixed value I or a certain time function I (t) has nothing to do with the voltage at both ends. Second, the current of the current source is fixed, and the voltage across it is arbitrary.

Because the current of the current source is fixed, the current source cannot be opened. When the current source is connected in series with the resistor, the effect of the external circuit is the same as that of a single current source. In addition, the current source and

Constant current has nothing to do with terminal voltage

Variable terminal voltage, independent of load

Power can be positive or negative

No open circuit allowed

Adjustable current source

DC current source (main parameters are output current, rated output power, etc.), and the adjustable output current is called adjustable current source.

Pulsed current source

The pulse ^[1] current mirror circuit uses a high-speed field-effect tube to replicate and multiply the constant current source current, reduce the impact of the pulse current source output load on the deep negative feedback part of the previous stage, and improve the stability of the circuit. The multiplexer controls the gate of the current mirror, and transmits the pulse signal to the pulse current, thereby outputting the pulse current.

Simulation experiments show that the proposed ^[2] pulse current source operates stably and reliably. The amplitude, repetition frequency, and pulse width of the output pulse current can be numerically adjusted. The current amplitude is stable and the pulse front is steep, which can meet different laser driving and Testing requirements.

Current source high precision current source

A high-precision current source circuit is proposed. Through V / I conversion, the band-gap reference voltage generated by the band-gap reference voltage circuit that is independent of temperature and power supply voltage is converted into a high-precision reference current that is independent of temperature and voltage. The high-precision current mirror structure generates the required mirror current, which effectively suppresses the influence of temperature, power supply voltage, load impedance changes and interference on the current source.