![]() ![]() This is useful as it can be used in digital block instead of using analog blockĪssign out=result => usually real number can be assigned to out in analog module (analog V(out) 1.2) ? 1'b1 : 1'b0 => This converts from real to signal. Another soln is to assign reg "gain" to integer which is signed by defn, and then perform "-" which gives signed result. Use real as one of the inputs, which makes the result real, which is signed. This is a huge ve number which causes vgain to be infinite, and hence convergence issues. However, since the result is supposed to be unsigned, this result is treated as unsigned number. This happens because result of operations on unsigned registers/nets is unsigned. Reg gain real vgain vgain = pow(10.0,(gain-32.0)/20) //here if we use integer 32 instead of real 32.0, then we get convergence error during sim complaining it's NaN. We have signals as electrical/voltage type, and variables as integer/real type. See also in simulation.txt for probe of ams signals. This is a good way to see how tool is working with analog signals.ĪMS simulator: see "running AMS" section in cadence_virtuoso.txt Then click on triangle or plus, and it will show the all the points where analog values were calculated. Then right click on signal value (where it shows the voltage/current number). timestep: To know the timestep for analog signals, we can display any anlog signal on waveform. At interfaces of analog and digital, tool tries to keep digital signals as much as possible to save on sim time.Ģ. Only when both 1st and 2nd logic are both analog or both digital, only then the signal will show up as only analog or only digital. Depending on whether they are placed on o/p pin of 1st gate or i/p pin of next gate, the signal may show up as an analog or digital signal in waveform viewer. If a digital goes into analog or vice versa, D2A or A2D connect modules are placed. NOTE: If a signal comes from srcVerilogAMS model, it's digital (0/1), while if it comes from schematic, it's analog (V/I). If we see *_$flow as signal name, it represents a current for that signal as opposed to voltage. If it shows a pulse type, it's digital, while if it shows sine wave, it' analog. ![]() A/D signals: On simvision gui, the way to know if a signal is digital or analog is to look at signal icon whenever we see at signal list to choose. So, we can probe any of these signals same way as we can probe any signal in Verilog-A.ġ. NOTE: all signals in regular schematics of transistors are electrical (since transistors are verilogA models with electrical input/output). Real x x=$cds_iprobe("TB.I0.net1) => this puts a current probe and continuously assigns value on net1 to var x. We add electrical, analog, contribution ( to probe volt/cur at any node. Verilog/AMS is a superset of the Verilog digital HDL, so all statements in digital domain work as in Verilog (see there for examples). Final plan is to pass accellera VAMS std to IEEE. The original intention of the Verilog-AMS committee was a single language for both analog and digital design, however due to delays in the merger process it remains at Accellera while Verilog evolved into SystemVerilog and went to the IEEE. It combines both Verilog and verilog-A, and then adds additional capability to allow description of mixed signal components. So, can simulate analog, digital and mixed ckt. Verilog analog and mixed signal (V-AMS) is a derivative of Verilog which extends event based simulator loops of digital simulation(V/SV/VHDL) by continuous time simulator. At top level, ncsim (or irun) is run on combined netlist. Spectre/TI-spice runs verilog-A, while ncsim runs verilog. It is the continuous-time subset of Verilog-AMS. Verilog-A standard does not exist stand-alone - it is part of the complete Verilog-AMS standard. Verilog-A was an all-analog subset of Verilog-AMS that was the first phase of the project. However, OVI wanted to create Verilog-AMS \ a single language covering both analog and digital design. MAST) and evolving into VHDL-AMS, OVI agreed to support standardization of spectre behavioral language to add analog capability to verilog. In face of competition from VHDL (an IEEE standard), which was absorbing analog capability from other languages (e.g. They are used for simulation only to verify complex blocks. Both these languages don't support synthesis. ![]()
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