diff --git a/src/openqlab/analysis/servo_design.py b/src/openqlab/analysis/servo_design.py
index b714335bded9df33890ff5a7c14e46fcfd524082..f6aeef2e3ff639e2535d97e2f2474d1a50b9ff43 100644
--- a/src/openqlab/analysis/servo_design.py
+++ b/src/openqlab/analysis/servo_design.py
@@ -231,7 +231,7 @@ class Differentiator(Filter):
 
 class Lowpass(Filter):
     """
-    Create a 2nd-order lowpass filter with variable quality factor `second_parameter`.
+    Create a 2nd-order lowpass filter with variable quality factor `second_parameter` (might be referenced as `Q` in the description).
 
     The default `second_parameter` of ``1/sqrt(2)`` results in a Butterworth filter with flat passband.
 
@@ -279,7 +279,7 @@ class Notch(Filter):
     corner_frequency: :obj:`float`
         Frequency to remove from the spectrum
     second_parameter: :obj:`float`
-        Quality factor of the notch filter. Defaults to 1.
+        Quality factor of the notch filter. Defaults to 1. Referenced as `Q` in description.
     """
 
     def __init__(self, corner_frequency, second_parameter=1, enabled=True):