cad123
Newbie level 2
Hello,
In doing dc sweep analysis of a CMOS transconductance amplifier, one gets a linear variation of o/p voltage (typically 18 mV to ~100mV) over a limited range of i/p variation before getting saturated. Ideally this linear range should also be consistent with THD results which is also another method of measuring the same. I am using cadence virtuoso (5.10.41) where I am getting a linear range of CMOS OTA as 40 mV (dc sweep) but when I am plotting THD (using PSS analysis with a suitable choice of fundamental tone) the results are totally inconsistent. Where it should start at around -80 dB for lower voltage levels up to -50 dB (monotonically), it is starting from -13 dB in my case which is absurd (attached image). Although DC analysis show the correct results, PSS analysis do not. How can this be interpreted.
Thanks in advance..........
In doing dc sweep analysis of a CMOS transconductance amplifier, one gets a linear variation of o/p voltage (typically 18 mV to ~100mV) over a limited range of i/p variation before getting saturated. Ideally this linear range should also be consistent with THD results which is also another method of measuring the same. I am using cadence virtuoso (5.10.41) where I am getting a linear range of CMOS OTA as 40 mV (dc sweep) but when I am plotting THD (using PSS analysis with a suitable choice of fundamental tone) the results are totally inconsistent. Where it should start at around -80 dB for lower voltage levels up to -50 dB (monotonically), it is starting from -13 dB in my case which is absurd (attached image). Although DC analysis show the correct results, PSS analysis do not. How can this be interpreted.
Thanks in advance..........
