Hi Guys,

I am wondering what a spectre simulator do for a "initial_step" block. For eg., I have an initial_step block as below. It is used to measure a PTAT voltage. An integer variable named dat is a digitized number for the input voltage, which is the PTAT voltage. Then I run a dc analysis in ADE-L, sweeping temperature from -40 to 125C. However, the dat is always equal to the number corresponding to -40C. In results browser, I check the dcOp-dc result, it varies if I change the number in Setup --> Temperature.... What's the difference between dcOp-dc and dc-dc for the Initial_step block?

Code:

   analog begin

	@ ( initial_step ) begin
	    halfref = vref / 2;
	   unconverted = V(vin);
		dat = 0;
	   for (i = (`NUM_ADC_BITS-1); i >= 0 ; i = i - 1) begin
		if (unconverted > halfref) begin
		   dat = dat + pow(2,i);
		   unconverted = unconverted - halfref;
		end else begin
		   dat = dat;
		end
		unconverted = unconverted * 2;
	   end
	end

 

Best Regards,
Yawei