gain cell as an example for the declarative small signal noise approach

examples/xspice/noise/noise_gain.cir

@@ -0,0 +1,22 @@
+Noise in gain code model
+
+a1 in1 out1 amp1
+.model amp1 gain(in_offset=0.1 gain=5.0
++ out_offset=-0.01 noise_voltage=1u noise_corner=2k noise_exponent=2)
+
+a2 in1 out2 amp2
+.model amp2 gain(in_offset=0.1 gain=5.0
++ out_offset=-0.01 noise_voltage=2u noise_corner=1k noise_exponent=1.2)
+
+Vin1 in1 0 1 ac 1
+
+.control
+noise V(out1) vin1 dec 333 1 1e6 16
+print inoise_total onoise_total
+noise V(out2) vin1 dec 333 1 1e6 16
+print inoise_total onoise_total
+set xbrushwidth=3
+plot noise1.onoise_spectrum noise1.inoise_spectrum noise3.onoise_spectrum noise3.inoise_spectrum loglog
+.endc
+
+.end

src/xspice/icm/analog/gain/ifspec.ifs

@@ -53,3 +53,25 @@ Vector_Bounds:       -                   -           -
 Null_Allowed:       yes                 yes         yes
 
 
+PARAMETER_TABLE:
+
+Parameter_Name:     noise_voltage        noise_current
+Description:        "noise voltage"     "noise current"
+Data_Type:          real                real
+Default_Value:      0.0                 0.0
+Limits:             -                   -
+Vector:              no                 no
+Vector_Bounds:       -                  -
+Null_Allowed:       yes                 yes
+
+
+PARAMETER_TABLE:
+
+Parameter_Name:     noise_corner        noise_exponent
+Description:        "1/f corner freq"   "1/f exponent"
+Data_Type:          real                real
+Default_Value:      0.0                 1.0
+Limits:             -                   -
+Vector:              no                 no
+Vector_Bounds:       -                  -
+Null_Allowed:       yes                 yes