What happens when a current source is shorted?

When connected to a short circuit, there is zero voltage and thus zero power delivered. One is its internal resistance and the other is its compliance voltage. The compliance voltage is the maximum voltage that the current source can supply to a load.

Why we use current source in differential amplifier?

Constant current sources are very useful to squeeze lots of gain out of an amplifying stage but they are also valuable to improve common mode amplification in the operational amplifier.

Why do we need a current source at the source of active transistors in common drain amplifier?

Current sources are needed in a number of different areas of electronics circuit design. Current sources can be used to bias transistors and can also be used as active loads for high gain amplifier stages. If ordinary resistors were used then the current would vary considerably over the voltage range.

Can a current source be shorted out?

If you short a current source you still get the current source current. So a perfect 1A current source will deliver 1A whatever the load – zero or 1M ohm. A real current source will not be quite as good.

Why current source is replaced by open circuit?

Both the sources replaced by its internal resistance… Voltage source have internal resistance equal to zero,hence it replaced by short circuit. While current source having internal resistance equal to infinity. Hence current source is replaced by open circuit.

Why Re is replaced by a constant current bias in a differential amplifier?

In the dc analysis of differential amplifier, we have seen that the emitter current IE depends upon the value of βdc. To make operating point stable IE current should be constant irrespective of value of βdc. To get very high value of resistance RE and constant IE, constant current bias is used.

What is necessity of current mirror circuit in differential amplifier?

Current mirrors are those boring circuits used to stabilise a circuit’s operation points under changing conditions such as varying load or temperature.

What happens to signals present in both inputs in a differential amplifier?

The differential amplifier circuit amplifies the difference between signals applied to the inputs (Figure 2.9). Superposition is used to calculate the output voltage resulting from each input voltage, and then the two output voltages are added to arrive at the final output voltage.

Why do we need current source?

The current source is needed because there are components and systems which must see a specific current value, rather than a specific voltage value. This is true in some ways, as current and voltage are linked by Ohm’s law (V = I × R). But using a voltage source in this way yields an inconsistent source of current.