Octago
Member level 1
Hello All,
A differential amplifier is implemented in my circuit( please see the picture in the attachment). The amplifier shown in the attachment is composed of a differential-input single-ended transconductance output stage and a source follower as buffer.
1, In my application, this amplifier has to drive a capacitive load (not more than 100pF), is it possible to just use this amplifier without source follower(use node A as output) or should I also include the buffer(use node B as output)?
By the way, the papers I read on operational amplifier or differential amplifier and so on always include a buffer stage; But in my simulation, I often find the circuits can work well and drive the following stage without any buffer. So I am wondering what is the essential advantage of a buffer? Or when should I use a buffer?
2, If I use A as output, than A should be connected with Vnn (as the red connection in the picture). Is it the correct cofiguration for negative unity gain feedback? The feedback ciruit sometimes has the problem of stability, for this circuit, how likely is it going to oscillate?
3. In order to increase the gain and the output voltage upper level, how can I optimize the transistor parameters (W/L)(M1-M4), (W/L)(M5-M6) of this amplifier?
thanks very much!
A differential amplifier is implemented in my circuit( please see the picture in the attachment). The amplifier shown in the attachment is composed of a differential-input single-ended transconductance output stage and a source follower as buffer.
1, In my application, this amplifier has to drive a capacitive load (not more than 100pF), is it possible to just use this amplifier without source follower(use node A as output) or should I also include the buffer(use node B as output)?
By the way, the papers I read on operational amplifier or differential amplifier and so on always include a buffer stage; But in my simulation, I often find the circuits can work well and drive the following stage without any buffer. So I am wondering what is the essential advantage of a buffer? Or when should I use a buffer?
2, If I use A as output, than A should be connected with Vnn (as the red connection in the picture). Is it the correct cofiguration for negative unity gain feedback? The feedback ciruit sometimes has the problem of stability, for this circuit, how likely is it going to oscillate?
3. In order to increase the gain and the output voltage upper level, how can I optimize the transistor parameters (W/L)(M1-M4), (W/L)(M5-M6) of this amplifier?
thanks very much!