Digital buffer  A digital buffer (or a voltage buffer) is an electronic circuit element that is used to isolate the input from the output, providing either no voltage or a voltage that is same as the input voltage. It draws very little current and will not disturb the original circuit. It is also called a unity gain buffer because it provides a gain of 1, which means it provides at most the same voltage as the input voltage, serving no amplification function. A voltage buffer has a very high input impedance (the opposition to current flow viewed from the load). The high input impedance is the reason a voltage buffer is used. A circuit with a voltage buffer will always draw a little amount of current because of the high input impedance of the buffer. As a result, the power source will not be affected. The digital buffer is important because it can control the on and off of data transmission, which is used widely in the world of registers (sophisticated data storage device) and buses (data transferring device). A typical digital buffer that is used to control multiple data inputs written onto a bus is a Tri-State Digital Buffer, which controls the data flow by "tri-state" pins. A digital buffer serves to transfer a voltage from a circuit that has a high output impedance level, to a second circuit with a low input impedance level. If we have a power source and a low impedance (resistor) load without a buffer, according to Ohm's law (voltage is equal to current times resistance), a huge amount of current is drawn from the source. As a result, huge amounts of power is drawn by the power source, which causes high disturbances. A voltage buffer always has a very high input impedance, approaching infinity; as a result, no matter what value the load impedance is, the source voltage will be totally spanned on the buffer impedance (because of Ohm's law); the voltage across the buffer impedance is the input voltage. Because the resistance is infinity, the circuit will draw very little current, and will not disturb the original circuit. Because the output current is generated by the voltage source via buffer, the buffer acts as a barrier between the source and load, thus preventing the load resistance affecting the source network. This kind of buffer produces the state opposite to the input. If the input is high, the output is low and vice versa. Graphically, it is often represented as a triangle with a small circle attaching to the tip. The inverter is a basic building block in digital electronics. Decoders, state machines, and other sophisticated digital devices may use inverters.