Hello,
In the datasheet,It says when a reduction in the noise of the current source is desired, a small capacitor can be placed across RSET (CSET in Figure 7).My Question if how to calculateThe vale of Cset?Iout I used is 200mA.
When C4 is10uF,There is noise on Iout.
Hi. Putting CSET in parallel with RSET on the LT3092 datasheet Figure 7 circuit can reduce noise, but it doesn't eliminate all the noise. CSET in that case just bypasses the current noise to RLOAD. The noise frequencies that are bypassed depend on the RSET CSET pole. If you bypass the SET pin directly to GND, then you won't see the noise from the current reference at the load, but the error amplifier of the LT3092 is still relatively noisy and that noise will appear at RLOAD. The LT3082 and LT3092 are essentially the same parts, but the LT3082 datasheet characterizes the error amplifier noise and the LT3092 datasheet does not. Our lowest noise current source is probably the LT3045-1 datasheet reference design called "Ultralow Noise Current Source for RF Biasing Applications". The LT3045-1 error amplifier has less noise compared to the LT3082/LT3092. I show all that in the images below.
