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somisetty Community Member Offline Posts: 64	Difference between two inverters Jun 16^th, 2009, 1:40am Hi all, what are the advantages and disadvantages between these two inverters? Thanks
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raja.cedt Senior Fellow Offline Posts: 1516 Germany	Re: Difference between two inverters Reply #1 - Jun 16^th, 2009, 5:15am hi, both are same ,you can't keep nmos drain potential less than source potenial Thanks, rajasekhar.
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uu@uk Junior Member Offline Posts: 17	Re: Difference between two inverters Reply #2 - Jun 16^th, 2009, 10:19am Hi, The first one is the source follower. it is better to use to drive resistor and it cannot give you rail to rail output. The second one is usually the inverter driving capacitor and easily get a rail to rail output. Also, the second one, is saving power.
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raja.cedt Senior Fellow Offline Posts: 1516 Germany	Re: Difference between two inverters Reply #3 - Jun 16^th, 2009, 10:22am hi, have you locked at both schematics, as soon you connect nmos on the bottom side immediately low potential point will be the source and remaining will be the drain....so how second ckt is possible? Thanks, Rajasekhar.
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HdrChopper

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Re: Difference between two inverters
Reply #4 - Jun 16^th, 2009, 6:31pm

uu@uk wrote on Jun 16^th, 2009, 10:19am:

Hi,

The first one is the source follower. it is better to use to drive resistor and it cannot give you rail to rail output. The second one is usually the inverter driving capacitor and easily get a rail to rail output. Also, the second one, is saving power.

In addition the second one has a large gain, therefore it reduces the delay between input an output signal provided both drive the same load.

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Keep it simple

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aamar

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Re: Difference between two inverters
Reply #5 - Jun 16^th, 2009, 11:35pm

It can not be a source follower, what rajasekhar wrote is correct. It is just a matter of flipping the symbol in the schematic but remains the PMOS connected to the highest voltage in the circuit and the NMOS to the lowest voltage. Assuming that the transistors are layouted symetrical so that the source and drain area of each transistor are equal.

In order to have a source follower then you have to connect the NMOS to the VDD and the PMOS to the VSS.

Best regards,

aamar

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raja.cedt Senior Fellow Offline Posts: 1516 Germany	Re: Difference between two inverters Reply #6 - Jun 17^th, 2009, 1:08am hi aamar, ya thats what even i am arguing.. And for the second argument it wont properly work as Source follower also, it shows hysteresis. thanks, rajasekhar.
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aamar Community Member Offline Posts: 57 Germany	Re: Difference between two inverters Reply #7 - Jun 17^th, 2009, 2:20am Yes rajasekhar, you are right, I meant just the principle but not that it is the optimum one.
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