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Re: How to measure the gain&phrase of a amplifier with S
Dear kongququ,
I am also doing this kind of design. The method I used is:
firstly, take off all the ac source, and do transient analysis for the amplifier, of course including the part of SC cmfb circuit. Then create it's final netlist...
Re: [help] urgent!!! about switched capacitor amplifier desi
Thanks sunking and Btrend!
2) ===> UGB > 1.664G
===> if A0= 1000 (i.e. 60dB), then ω0 > 1.664M rad/s ===> f0 > 264 kHz/s
/***According to what you said, does the amp( A0=10000 (80dB), f0 > 26.4 kHz/s) can meet the...
Hello, everyone!
I want to design a 12bit switched capacitor amplifier with following specs: 12 bit , closed-loop gain is 10, sampling freqency is 10MHz, supply voltage is 3.3V. and power consumption is not very restrict.
I have several questions:
1) To a switched capacitor amplifier, 12 bit...
Hi vavinash,
I don't know why I cannot attach it on.
So, try one more time!
If you still cannot see it, leave your email address, maybe I can email it to you!
how to decide gbw of ota
Thank you Vamsi!
As we known, when apply a large signal to the opamp, for example 1Vpp, one of the input transistor of opamp turns off, the other is still on, so the slew rate SR=Iss/Cc.
But for an amplifier, we also want to get a voltage gain (Vout/Vin). For...
hi avinash,
yes, what I said above is the method to measure the AC open loop spec. of opamp.
Please refer to this document, I think you can get what you want to know!
hi avinash,
I usually provide two oppsite ac signals to input+ and input-. and of course, connect two output with load capacitors. Then do ac analysis, and check the result of AC magntude & Phase for the ugb and phase margin.
switching capacitor amplifier
Thanks a lot! But I am still confused with it. I think maybe the sampling freqency is too high to my circuit. because for 2MHz sampling frequency, the output waveform is normal . But how to do to make it work at 10MHz sampling frequency?
The spec. of inner opamp I...
using class ab switched capacitor
In order to design a switched capacitor amplifier with gain 10, sampling frequency 10MHz.
1) How to decide the specs of it's inner opamp? (Such as unity-gain frequency, slew-rate, etc. )
2) Which kind of opamp can easily be designed to match this request...
Usually both of them are not the total current consumed by the Opamp. because the character of 'current controll voltage.' one current can be copied to severals. so the current consumed by the Opamp is the total current of all subcircuit .
wide gbw
Thank you. In fact the supply voltage is 3.3V, TSMC0.25 Process. (Vtn 0.52V, Vtp 0.85V) and load capacitance 1pF.
At first I set compensation capacitance to 250fF, but it seemed the phase margin is not enough(52), on the other hand if I increase the compensation capacitance, there...
high gbw op
I need a Opamp with DC gain>80dB and Unity Gain frequency >100MHz. At first I try to design it with the class-A two-stage structure. but it is difficult to satifiy both the DC gain and phase margin.
Who can give me some advice about how to design. such as, if class-A structure can...
Re: SC CMFB circuit?
I see, but if I only apply the CMFB to the first-stage of the opamp, the circuit like following:
Vcm is connected to the output of the first-stage. Vcmfb is connected with the bias of the first-stage. How can I control the output voltage of the second-stage?
Thanks again!
Re: SC CMFB circuit?
Thank you for you answer. But as you said, if I adopt the first methold, that is to say, only apply the CMFB to the first stage. So, how can I control the output voltage and make it equal to the input voltage? it is difficult to decide the Vcm, isn't it?
Thanks a lot!
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