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Negative Power Supply Voltage

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qiushidaren

qiushidaren

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negative voltage battery

Hi, all!
I wanna know what are the advantages of negative power supply voltage which has been widely used in op amps, and how can we implement negative power supplies in IC?
Thank you in advance!
 

555 voltage inverter

The main advantage is that with simmetrical power supplies (rails) you can handle AC signals without DC offsets. If you have only positive rail, the output signal can assume only positive values, in the other hand, with positive and negative rails, the output signal swings from negative to positive voltages.

For low power OpAmps, you can use the ICL7662 to generate the negative rail from a single positive supply (for example, you have 12V positive, ICL7662 generates -12V @ 50mA)
 

negative voltage from battery

qiushidaren said:
what are the advantages of negative power supply voltage which has been widely used in op amps
Click to expand...
The principal advantage is that the op amp has the ability to handle bipolar inputs and generate a bipolar output.

This is important in applications (e.g., process control) where real world signals are bipolar. Also, it is essential for interfacing to industrial standards such as motor control, where positive voltages cause "clockwise" rotation and negative voltages cause "counter-clockwise" rotation, and the voltage amplitude controls the velocity.
 

negative voltage from positive supply

rkodaira said:
The main advantage is that with simmetrical power supplies (rails) you can handle AC signals without DC offsets. If you have only positive rail, the output signal can assume only positive values, in the other hand, with positive and negative rails, the output signal swings from negative to positive voltages.

For low power OpAmps, you can use the ICL7662 to generate the negative rail from a single positive supply (for example, you have 12V positive, ICL7662 generates -12V @ 50mA)
Click to expand...
Thanks for your explanation, I still want to know more details about how to implement a negative power supply voltage in IC, I mean I want to know the pricinples, e.g. a bandgap reference voltage, it's positive voltage have been fixed with respect to ground, so if we connect the positive voltage given by BGR to ground the output is shorted we can't get a negative voltage as a battery, for a battery we just need to connect one of its terminals to ground we can get a positive or negative voltage for the other terminal. I'm a little bit conbused about this question.
 

advantage of negative voltage

You need two batteries. One for positive supply, the other for negative supply.

qiushidaren said:
Hi, all!
I wanna know what are the advantages of negative power supply voltage which has been widely used in op amps, and how can we implement negative power supplies in IC?
Thank you in advance!
Click to expand...
 

-12v from positive supply

If you are designing an IC and you want to integrate a negetive voltage generator on the chip, then you need to put a Voltage inverter on the chip and the inductor and capacitor outside the chip. if you want anegetive supply to power your IC, you can use a 555 voltage inverter.
 

negative voltage supply

isaacnewton said:
You need two batteries. One for positive supply, the other for negative supply.

qiushidaren said:
Hi, all!
I wanna know what are the advantages of negative power supply voltage which has been widely used in op amps, and how can we implement negative power supplies in IC?
Thank you in advance!
Click to expand...
Click to expand...
If I don't use battery for negative voltage, how can I implement it in other way?
 

negative voltage advantage

qiushidaren said:
If I don't use battery for negative voltage, how can I implement it in other way?
Click to expand...
Perhaps you can generate a negative voltage from the positive rail with a charge pump.
 

negative power supply

there are many method to implement: ex, based on op amp, based on charge pump, ...
 

negative supply from single positive supply

Charge pump .
But charge pump has many shortcomings or limits .
 

advantage of negative supply

fanrong said:
But charge pump has many shortcomings or limits .
Click to expand...
All methods for generating negative voltages have shortcomings and limitations, and charge pumps are certainly no exception. However, it makes no sense to rule out a charge pump before determining its suitability for this application. If a charge pump can be used here, it may have very favorable advantages over other methods.
 

positive and negative rails -patent

here is a simple -ve voltage generator....but i dont its current rating......but it is so simple it's hard to ignore.....it is in given in the icl7106 datasheet page no 10
**broken link removed**
i think u can remove the cd4009 part and just add a oscillating source of some freq i dont know the exact value.......
 

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