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Help needed for BGR
Hi,
I am trying a BGR design (Pls see the attached file ). Initially I am just forcing a constant voltage to both the BJT's which is normally done thru an opamp. I dont know if there is the correct way but I did like that bcoz I dont have a very good opamp design with me as...
Hi,
I am trying to use a MOSFET in place of a resistor. I am new to ckt design and I am finding it very difficult to bias it. Can anyone help me to understand how to bias a MOS in linear region so that it can act as a resistor. I used the ckt attached but I dont know if its the correct way to...
Thanks a lot for the specs. Could you pls help me to understand how UGB determines the tail current. And I dont know how to get the mobility and Cox values to plug-in into my equations. Is there any specific file that contains these things?
I am using a 45nm process.
yeah.. I havent added a load cap. I am using an ideal 1pF cap as of now. Actually I am trying to learn to design. So, I dont have any realtime specs with me. I also dont know how much I can take for UGB. As I have mentioned earlier, I am mainly targeting on the gain...
But I would like to know how to get these values for a particular process. I think it will vary across the fabs. For eg. if I use TSMC 45nm process, where can I get these values (so that I can use it for ahnd calculations of my design). Is there any specific file in the pdk that contains these info?
Hi,
I am trying to design a simple opamp with a gain of 60dB. I am targetting a gain of around 40dB for the differential stage and 20dB for the second stage. I am not considering any other spec as of now. The supply voltage is 1.2V. Length of transistors is fixed at around 0.09um.
I cudnt...
Actually why I want to understand this phenomena is that, in resistorless BGR design, 2 different currents are fed to BJTs having same area to generate delta-Vbe. So, I want to understand how the Vbe is increasing with increase in collector current
Hi Kr,
If I maintian the same emitter area for both the BJTs, and force more collector current through one of the BJTs, then what will be the change in Vbe?
I think the BJT carrying more current will have higher Vbe (as seen from the equations). Now, how does more collector current requirement...
Yeah. I am able to understand now from the equations. So, from the device physiscs point of view, more emitter area results in more minority carriers being swept across the junction and hence more Is? Is my understanding correct...
Hi,
In BGR, the delta-Vbe is generated by maintaining a particular ratio of emitter area. Typically the transistor having higher emitter area has lesser Vbe for the same current. I would like to understand the physical reason behind the same. I have seen the literature, but they all prove this...
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