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language:langs:sizing [2020/12/02 01:00]
127.0.0.1 external edit
language:langs:sizing [2021/03/07 07:33]
rajit [Low leak addition on channel length]
Line 114: Line 114:
 This is an example of defining two standard inverters, that correspond to the same logical production rules but having different sizing. This is an example of defining two standard inverters, that correspond to the same logical production rules but having different sizing.
  
 +===== P/N ratios =====
 +
 +The default sizing equalizes drive strengths for the pull-up and pull-down network. For gates used in cyclic control logic in asynchronous design, the optimal drive strengths are different. To use the optimal ratio, you can add:
 +
 +<code>
 +
 +prs {
 +  in[1] & in[0] #> out-
 +}
 +sizing {
 +  p_n_mode <- 1; /* this modifies the sizing */
 +  out {-1}
 +}
 +</code>
 +
 +The ratio will be computed using parameters in the netlist section of the ACT [[config:netlist|configuration]] file.
 +
 +
 +===== Low leak addition on channel length =====
 +
 +In some technologies, the minimum length devices have extremely high leakage. To avoid using these, you can specify an adjustment that will be added to the length to avoid this case. This adjustment is only applied to minimum length devices.
 +
 +For adding a specified additional length to the minimum length of your transistors, activate ''leak_adjust''.
 +
 +<code>
 +prs {
 +  in => out-
 +}
 +sizing {
 +   leak_adjust <- 1;
 +   out{-1}
 +}
 +</code>
 +
 +To configure how much is added add this line to the configuration
 +
 +<code>
 +# add to length for leakage management [used if l=min length]
 +real leakage_adjust 15e-9
 +</code>
 +
 +The length unit here is absolute (i.e. not scaled), so the amount specified above is 15nm.