Add a limit capability to the code model aswitch

Example switch-oscillators_inc.cir showed currents up to 3GA

examples/p-to-n-examples/switch-oscillators_inc.cir

@@ -3,14 +3,13 @@
 .control
 destroy all
 run
-plot I(vmeasure)
+plot I(vmeasure) ylimit 0 5m
 plot V(Osc_out)
 rusage
 .endc
 
 .ic v(N017)=0.25
-.tran 50p 40n 50p uic
-*.option method=gear maxord=3
+.tran 50p 40n 50p
 
 VDD VDD2 0 DC 3
 

src/frontend/inpcom.c

@@ -8029,7 +8029,7 @@ static struct card *pspice_compat(struct card *oldcard)
                 tfree(card->line);
                 rep_spar(modpar);
                 card->line = tprintf(
-                        ".model a%s aswitch(%s %s %s %s  log=TRUE)", modname,
+                        ".model a%s aswitch(%s %s %s %s  log=TRUE limit=TRUE)", modname,
                         modpar[0], modpar[1], modpar[2], modpar[3]);
             }
             for (i = 0; i < 4; i++)
@@ -8210,7 +8210,7 @@ static struct card *pspice_compat(struct card *oldcard)
                 tfree(card->line);
                 rep_spar(modpar);
                 card->line = tprintf(
-                    ".model a%s aswitch(%s %s %s %s  log=TRUE)", modname,
+                    ".model a%s aswitch(%s %s %s %s  log=TRUE limit=TRUE)", modname,
                     modpar[0], modpar[1], modpar[2], modpar[3]);
             }
             for (i = 0; i < 4; i++)

src/xspice/icm/xtradev/aswitch/cfunc.mod

@@ -150,7 +150,14 @@ void cm_aswitch(ARGS)  /* structure holding parms,
     if ( PARAM(log) == MIF_TRUE ) {   /* Logarithmic Variation in 'R' */
         intermediate = log(r_off / r_on) / (cntl_on - cntl_off);
         r = r_on * exp(intermediate * (cntl_on - INPUT(cntl_in)));
+
+        if (PARAM(limit) == MIF_TRUE) {
+            if(r<r_on) r=r_on;/* minimum resistance limiter */
+            if(r>r_off) r=r_off;/* maximum resistance limiter */
+        }
+        else {
             if(r<=1.0e-9) r=1.0e-9;/* minimum resistance limiter */
+        }
         pi_pvout = 1.0 / r;
         pi_pcntl = intermediate * INPUT(out) / r;
     }
@@ -158,14 +165,18 @@ void cm_aswitch(ARGS)  /* structure holding parms,
         intermediate = (r_on - r_off) / (cntl_on - cntl_off);
         r = INPUT(cntl_in) * intermediate + ((r_off*cntl_on - 
                 r_on*cntl_off) / (cntl_on - cntl_off));
+
+        if (PARAM(limit) == MIF_TRUE) {
+            if(r<r_on) r=r_on;/* minimum resistance limiter */
+            if(r>r_off) r=r_off;/* maximum resistance limiter */
+        }
+        else {
             if(r<=1.0e-9) r=1.0e-9;/* minimum resistance limiter */
+        }
         pi_pvout = 1.0 / r;
         pi_pcntl = -intermediate * INPUT(out) / (r*r);
     }                                 
 
-    /*pi_pvout = 1.0 / r;*/
-
-
     if(ANALYSIS != MIF_AC) {            /* Output DC & Transient Values  */
         OUTPUT(out) = INPUT(out) / r;      /* Note that the minus   */
         PARTIAL(out,out) = pi_pvout;       /* Signs are required    */

src/xspice/icm/xtradev/aswitch/ifspec.ifs

@@ -67,11 +67,11 @@ Null_Allowed:      yes                  yes
 
 PARAMETER_TABLE:
 
-Parameter_Name:    r_on	
-Description:       "on resistance"
-Data_Type:         real 
-Default_Value:     1.0	 
-Limits:            - 
-Vector:             no 
-Vector_Bounds:      - 
-Null_Allowed:      yes 
+Parameter_Name:    r_on	                limit
+Description:       "on resistance"      "set upper and lower limits to resistance"
+Data_Type:         real                 boolean
+Default_Value:     1.0	                false
+Limits:            -                    -
+Vector:             no                  no
+Vector_Bounds:      -                   -
+Null_Allowed:      yes                  yes