Is there an alternative to resistive voltage divider?
In the case when power dissipation through the resistors (or their size) is not acceptable, what would be a way out and at which cost?
Is there an alternative to resistive voltage divider?
In the case when power dissipation through the resistors (or their size) is not acceptable, what would be a way out and at which cost?
Plenty of alternatives I'm sure, but it depends on what you want the circuit to do. A resistive voltage divider, is a confuguration of components, it's purpose in a circuit is what's important, (attenuation, creating a reference etc.).
I was thinking more about creating a reference.
Can I do it with some other configuration, having a negligible power consumption, at the cost of precision, for example?
For high performance references, people usually use bandgap cells. However, this may not be an optimum solution at your case because it may consume considerable power and area.
One example: LDO regulator for low voltage & ultra low power (uW). When I buffer voltage reference, I need a resistive voltage divider at the output. If the current through them should be low, they need to be large. Can I avoid that?
I am not really a specialist in LDO design, but I wonder if one could drop the voltage divider completely. In this case, the reference voltage should be identical to the regulated voltage (and not identical to a part of it). So what ?
Perhaps somebody else can comment to this approach.
After a while some doubts came into my mind concerning common mode properties of the error amplifier, if both inputs are at the regulated voltage level; and at the same time the amplifier supply is between ground and the unregulated input voltage. I think this will not work.
You need a bandgap, a buffer which multiplies the bandgap to the the LDO input and the LDO.
To minimize the area for resistors you can use PMOS with Well connected to source to divide voltage. But it works only for integer division ratios. To reduce the power at all you can power cycle the bandgap and the multiplying buffer and S/H the LDO input voltage.
bare in mind that resistor voltage divider is temperature independent because their coefficient cancels out. You might lose this nice property if u were to choose a different approach.
You need a bandgap, a buffer which multiplies the bandgap to the the LDO input and the LDO.
To minimize the area for resistors you can use PMOS with Well connected to source to divide voltage. But it works only for integer division ratios. To reduce the power at all you can power cycle the bandgap and the multiplying buffer and S/H the LDO input voltage.
Sample the reference on a cap A. Place an empty cap B in parallel. Charge on A now has to divide over A+B. Voltage has been divided. But this requires some switches and linear caps. Don't know if it safes much power.