81.1.9. Conclusion on current reference

The current mirror circuit can also be used for current mode amplifier. In fact, this is also recapitulation for us that we have seen if we require one circuit basically one current mode amplifier. If we want to cascade it with another current mode amplifier and the impedance of the previous stage and the next stage if they are not well matched. And then if the moment we cascade it may create some loading effect and that may degrade the overall performance of the circuit.

Current mirrors are essential in analog circuits because they help maintain consistent performance when multiple amplifiers are connected. When connecting two amplifier circuits in a sequence (cascading), if the output impedance of the first amplifier does not match the input impedance of the second, it can create a loading effect. This loading effect can distort signals and degrade the performance of the overall system. A current mirror acts as an intermediary buffer that can stabilize the current flow and improve the interaction between the two stages.

Think of a current mirror like a bridge that connects two islands (the amplifiers). If the bridge (current mirror) is weak, vehicles trying to cross might get stuck or damaged, leading to traffic delays (signal degradation). A strong bridge allows for smooth traffic, ensuring everything runs efficiently. In electronic circuits, this 'strong bridge' helps maintain proper signal flow and quality.

So, what we may require we can place one circuit in between, which is supposed to be working as a buffer and this is the model of that buffer. So, this is the model of the buffer here we do have and the input current it is i . So, this is the internal circuit of on buffer.

In a circuit design, a buffer circuit is typically placed between two components to match their impedances without compromising signal integrity. In this case, the buffer is designed to have low input impedance and high output impedance, allowing it to transfer current effectively while isolating the stages. This configuration ensures that the current flowing into the second amplifier stage remains stable and unaffected by changes in the first stage.

Imagine a relay race. The runner (the buffer) must pass the baton (the signal) to the next runner without altering its speed or direction. If the first runner is too strong or too weak, he can change how the baton moves, potentially causing the second runner to stumble or drop it. The buffer helps maintain the same speed and smooth handoff, ensuring the race continues without errors.

So, this current mirror circuit can also work as current mode buffer, which means that the current mirror it is having input impedance low. And also the output resistance it is high and the current gain not only it will be one. In fact, the current gain it can be even higher than 1.

Current mirrors are versatile components that can function as current mode buffers due to their unique characteristics. They provide low input impedance, high output resistance, and can amplify current. This means that not only do they manage the current levels effectively, but they can also enhance the current to ensure that it meets the requirements of subsequent circuit stages without losing quality.

Consider a bank teller (the current mirror) who handles deposits and withdrawals (current levels) for customers (circuit components). The teller can manage a few customers efficiently (low input impedance), but can also handle larger withdrawals than what was originally deposited (current gain higher than one). This allows for flexible banking operations, ensuring that customers receive prompt service regardless of how busy the bank is.

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