Decoupling
There are instances where the power distribution between stages cannot be sufficiency bypassed. In this case, the designer might be tempted to use several different power supplies. However, by supplying the DC power to each stage through a separate inductor or "choke," while also bypassing to ground that stage, the effect is the same. That is to say, the choke offers a high impedance path to any errant signals or noise between stages, while offering a very low resistance path to the DC power: this is known as decoupling. Active devices such as voltage regulators can also be used for decoupling stages.