`include "constants.vams"
`include "disciplines.vams"

module opa_fd1(inp, inn, outp, outn);

	inout inp, inn;
	inout outp, outn;
	
	electrical inp, inn, outp, outn;
	real vin, voutp, voutn, vout0, ioutp, ioutn;
	
	parameter real GAIN      = 10000 from (0:inf), 		// open loop gain
	               POLE_FREQ = 1M from (0:inf),		// cut-off frequency
	               Rout      = 100 from (0:inf);		// output Resistance

	analog begin
		vin     = V(inp, inn);
		voutp   = V(outp);
		voutn   = V(outn);
        
        	// dominant pole
        	vout0 = laplace_nd(GAIN*vin, {1},{1,1/(`M_TWO_PI*POLE_FREQ)});
        		
        	// output current
        	ioutp = (vout0 - voutp)/Rout;
        	ioutn = (-vout0 - voutn)/Rout;
        	
        	// output curent
        	I(outp) <+  -ioutp;
        	I(outn) <+  -ioutn;
        end
        
endmodule