jmdennis
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Hi all,
I am now designing circuit using AMS C18 process. Its core power supply is 1.8V.
I start from very basic block, say PMOS-input 2 stage opamp. The common mode input range is from near zero volt to about 1V. DC bias at 0.5V gives the best result of gain, and it also gives wide range of input signal amplitude.
But Here is the question. Every time when I use opamp, I have to bias 0.5V at the input. My input signal is usually AC signal. To add extra DC voltage, I use source follower. It indeed does its job but the gain seems to reach the maximum at 0.82 , even I gives a ridiculously large source resistance (>100G).
lt
I would like to ask for advices. What are the best approach to bias circuit in the single power supply? Dual power supply seems more flexible and mid-point at zero volt is easy for signal processing.
Many Thanks.
Daniel
I am now designing circuit using AMS C18 process. Its core power supply is 1.8V.
I start from very basic block, say PMOS-input 2 stage opamp. The common mode input range is from near zero volt to about 1V. DC bias at 0.5V gives the best result of gain, and it also gives wide range of input signal amplitude.
But Here is the question. Every time when I use opamp, I have to bias 0.5V at the input. My input signal is usually AC signal. To add extra DC voltage, I use source follower. It indeed does its job but the gain seems to reach the maximum at 0.82 , even I gives a ridiculously large source resistance (>100G).
lt
I would like to ask for advices. What are the best approach to bias circuit in the single power supply? Dual power supply seems more flexible and mid-point at zero volt is easy for signal processing.
Many Thanks.
Daniel