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https://designers-guide.org/forum/YaBB.pl Design >> Analog Design >> Help Needed !! Instrumentation Amplifier - Phase Margin https://designers-guide.org/forum/YaBB.pl?num=1386319308 Message started by shaikss_rf on Dec 6th, 2013, 12:41am |
Title: Help Needed !! Instrumentation Amplifier - Phase Margin Post by shaikss_rf on Dec 6th, 2013, 12:41am Hi, I am working on the design of Instrumentation amplifier for ECG system. Initially, I designed a Difference differential amplifier. When I checked the Gain and Phase margin response, the system is highly unstable. I observed phase margin in negative value and 3dB cut off frequency at ten's of MHz. I tried to add a resistor in series with cap but there is no change in Phase margin. I did pole-zero analysis: Poles: 1. -3.22+02 Hz 2. -5.417+07 hz 3. -2.513+07 Hz 4. -9.684e+07 Hz 5. -3.19e+08 Hz 6. -5.27+e08 Hz Zeros 1. -2.7941e+06 Hz 2. -4.922e+07 Hz 3. -9.679 e+07 Hz 4. -3.14e+08 Hz 5. 6.94232e+07 Hz 6. 2.43 e+09 Hz 7. 9.01661 e+09 Hz Can you pls tell me how to improve the Phase margin? |
Title: Re: Help Needed !! Instrumentation Amplifier - Phase Margin Post by lvbq on Dec 10th, 2013, 5:01am there are so many Mirroring poles and zeros, why use this architecture ? |
Title: Re: Help Needed !! Instrumentation Amplifier - Phase Margin Post by boe on Dec 10th, 2013, 8:17am shaikss_rf wrote on Dec 6th, 2013, 12:41am:
Which approach did you use for sizing the compensation cap? - B O E |
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