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benefit of folded cascode opamp

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avinash

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folded cascode op amp

what is the benefit of using folded cascode opamp over telescopic opamp.
 

jayc

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folded cascode op-amp

Greater output swing
 

vlsiattitude

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folded cascode advantages

rather it gives u advantage of cascodes without trading swing
 

jinxingsun

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what is a folded cascode amplifier benefits

Fold cascode opamp can offer good input common-mode range and self-compensation.
 

chinito

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folded cascode self compensating

+ good input CM range, output CM range decoupled from input CM.
- current runs in third branch
- pole at folding node
 
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avinash

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telescopic amp

i can understand that ICMR of folded cascode is better than the telescopic one.but how come the voltage swing is higher in folded cascode (telescopic amplifier has current source as load).
 

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telescopic vs folded cascode

avinash said:
i can understand that ICMR of folded cascode is better than the telescopic one.but how come the voltage swing is higher in folded cascode (telescopic amplifier has current source as load).

The tail current source in telescopic cascode makes the swing lesser (by one Vdast which is required to keep it in saturation). This Vdsat reduction is not present for the output swing in the folded cascode, which makes the swing of the folded cascode higher (by atleast Vdsat of the tail current mirror) as compared to a telescopic cascode.
 
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opamp741

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benefit of cascode

u will get extra swing (~200mV) at the cost of power (~double) and nondominant pole..
 

nagula suresh

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folded cascode opamp

folded cascode compared to telescopic will have the currentsource less,so voltge swing difference of vdsat between the two.
but compared to telescopic it will have more noise,because of the folded legs.
and the speed is more for telescopic than folded.,
but in low voltage designs unable to maintain the swing by telescopic.
 

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Folded Cascoded Amplifier
Advantages:
1. High Gain
2. Improved Bandwidth
3. High Slew rate
4. High stability
5. High input impedance
6. The folded cascode Opamp is useful for moderately low supply voltages, at the cost of some extra current, but has limited performance in sub 1V applications, as well as a limited Vcm(in).

Telescopic Amplifier
Advantages
Usually provides best trade off between
1. Gain
2. Power dissipation
3. Speed
4. Noise
5. Higher Frequency Capability

Disadvantages
1. Output swing is limited and shorting input and output is difficult
 
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nlkk

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Re: folded cascode op amp

Although the folded cascode has the above advantage, it does not fit for the current sub-1v application. the trend has changed.
 

Dominik Przyborowski

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Re: folded cascode op amp

Although the folded cascode has the above advantage, it does not fit for the current sub-1v application. the trend has changed.
Ohh, it's not so bad. If technology provides low-Vt devices we are able to use self-cascodes and also some very low voltage cascode current sources exists which works with minimum voltage drops in the range of 50mV (with 0.5V of MOS threshold voltages) and very high output impendance.
 
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Mixed signal subject , higher rate for power line communication , and I found in computer board designed of a brand of company that minimum transformer.
 

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