I have been working on some boards with TI CC430 processor + radio chips. It amazes me how much is crammed into that part. It includes a complete multiband transceiver with 10mW output.
The radio portion runs on 2V and a built-in linear regulator allows you to power it with 2.1 to 3.6V. Since it’s a linear regulator, the current is the same regardless of the input voltage, so it pays to use the lowest input voltage possible.
Earlier this week I was working out a scheme to do this for the radio portion and the processor portion. I thought I could save power by reducing the voltage to the processor, but it turns out the CC430 chip has a built-in inductorless switching regulator to power the processor core. So if you lower the input voltage, the current increases leaving the power roughly constant. This means the engineer using this part can use any supply within the allowed range without it affecting power consumption.
What more could they do to the CC430? Could the next step be a switching power supply for the radio portion too?