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https://designers-guide.org/forum/YaBB.pl Design >> Analog Design >> How to calculate bias current https://designers-guide.org/forum/YaBB.pl?num=1245069924 Message started by icekalt on Jun 15th, 2009, 5:45am |
Title: How to calculate bias current Post by icekalt on Jun 15th, 2009, 5:45am Can someone explain@help to determine the value of Ibias? You can find the circuit in the attachment. VDD is 3.3V and the MOS technology used is 0.35µm. thx in advanced |
Title: Re: How to calculate bias current Post by raja.cedt on Jun 15th, 2009, 6:03am hi, thats mainly in your hand only, i guess this is a first stage of an comparator, so based on the input resolution you might have some gain and you know how much time in your hand for first stage so based on that how much gm you need and for that gm you can find how much current in the input differential pair and double of that current is what you want.Listen this is the not only the way... Thanks, rajasekhar. |
Title: Re: How to calculate bias current Post by pancho_hideboo on Jun 15th, 2009, 6:12am icekalt wrote on Jun 15th, 2009, 5:45am:
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Title: Re: How to calculate bias current Post by raja.cedt on Jun 15th, 2009, 6:31am hi, i forgot to ask ,how did you come up with diff amp w/l ratio,don't you consider current in that case? Thanks, Rajasekhar. |
Title: Re: How to calculate bias current Post by icekalt on Jun 15th, 2009, 6:49am raja.cedt wrote on Jun 15th, 2009, 6:31am:
i just randomly selected it..:) |
Title: Re: How to calculate bias current Post by icekalt on Jun 15th, 2009, 6:56am pancho_hideboo wrote on Jun 15th, 2009, 6:12am:
hello pancho_hideboo, are you referring the load capacitance to the diode connected loads(two PMOS)? |
Title: Re: How to calculate bias current Post by pancho_hideboo on Jun 15th, 2009, 7:09am icekalt wrote on Jun 15th, 2009, 6:56am:
http://www.zen118213.zen.co.uk/RFIC_Circuits_Files/MOS_OP-Amplifier_Intro.pdf http://www.zen118213.zen.co.uk/RFIC_Circuits_Files/MOS_OP-Amplifier_Example.pdf |
Title: Re: How to calculate bias current Post by uu@uk on Jun 15th, 2009, 8:30am Hi, What is the amplifier for? If it is driving capacitors and you need high swing at the output. The slew rate may also give you some idea about the bias current. Thanks uu@uk |
Title: Re: How to calculate bias current Post by thechopper on Jun 15th, 2009, 1:20pm Hi, On top of what was already suggested, also input noise and offset levels might be controlled by means of Ibias. Regards Tosei |
Title: Re: How to calculate bias current Post by icekalt on Jun 16th, 2009, 5:34am uu@uk wrote on Jun 15th, 2009, 8:30am:
thx uu@uuk. The amplifier is for the comparator. It has to amplify the difference of two signals. |
Title: Re: How to calculate bias current Post by icekalt on Jun 16th, 2009, 5:37am What is the best analysis to simulate that circuit? transient or ac or dc sweep?? |
Title: Re: How to calculate bias current Post by icekalt on Jun 16th, 2009, 5:44am pancho_hideboo wrote on Jun 15th, 2009, 7:09am:
halo pancho_hideboo, I just have read through the documents. Do you have example for differential amplifier used in comparator? the one that you give me is used in op-amp..thx |
Title: Re: How to calculate bias current Post by uu@uk on Jun 16th, 2009, 10:14am icekalt wrote on Jun 16th, 2009, 5:37am:
If your amplifier is for a comparator, I think you need both transient and DC analysis. transient could tell you the rise/fall edge rate. DC analysis can check the FETS are all working in the right region. good luck. |
Title: Re: How to calculate bias current Post by icekalt on Jun 17th, 2009, 7:15am uu@uk wrote on Jun 16th, 2009, 10:14am:
Thx uu@uk. Can you explain me more about rise/fall edge? How to know if our MOS transistors working in the right region based on simulation? thx |
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