The Xcelium simulator with mixed-signal option supports CPF-influenced analog blocks by identifying them and inserting power-smart connect modules (CMs) during elaboration. The selection and insertion of power-smart connect modules complies with the Verilog-AMS language semantics. The connect rules in the Cadence installation have been enhanced to include power-smart connect modules. The power awareness of a connect module is determined by the tool on the basis of the connect module name (that is, the name ending with "LPS"). The power-smart connect modules (L2E/R2E) use an additional parameter named vpso. This parameter is used to specify the voltage value, which must be passed to the analog block when the digital block driving it is shut off. The default value of the vpso parameter is 0.2.
You can also use the parameters vtrlo, vtrhi, and vrtol in power-smart connect modules to specify the ratio of low threshold, high threshold, and tolerance during value conversion.
Additionally, power-smart connect modules have been enhanced to support the current mode, in which electrical current is converted between wreal and electrical connection. When current mode processing is enabled for an LPS connect module, the behavior of the LPS connect modules is same as a regular connect module. And, the tool issues a warning that the current mode behavior is not low power-aware though the connect module is *_LPS.
Info: Current mode processing enabled for this low power aware connect module (tb.topInst.connect__E2R_LPS__ddiscrete_1_8). Note that low power aspects are not expected to influence the current mode behavior
The following diagram illustrates how power-smart CMs carry the effect of digital power-shutoff (PSO) to analog blocks:
The design instances are Inst_A, Inst_B, Inst_C, and PM. Inst_B is an analog block connected to Inst_A. The dotted outlines indicate the two power domains, PD1 and PD2. Inst_A belongs to power domain 1 (PD1) and Inst_C belongs to power domain 2 (PD2). PM is a power manager module. The power control signals, PD1_ctrl and PD2_ctrl, correspond to power domains 1 and 2, respectively.
The power-smart L2R/E2R CMs carry the effect of PSO to RNM blocks with wrealXState and the power-smart E2L/R2L CMs carry the effect of PSO to digital blocks with X.
The Xcelium simulator with mixed-signal option allows the use of automatically inserted as well as manually inserted power-smart connect modules. The automatically inserted connect modules are selected by the tool based on the connect rules and connect libraries provided by the user. The manually inserted connect modules are explicitly instantiated by the user in the design and do not need any connect rules.
The Xcelium simulator with mixed-signal option supports designs containing VHDL-D drivers that directly or indirectly impact power-smart connect modules in the low-power mixed-signal simulation. However, this support is currently not available for VHDL-SPICE cases where VHDL conversion elements (CEs) are used.
Also, the power-smart connect modules support advanced power-domain features like power modes and nominal conditions, resulting in improved digital-to-analog transition inside the modules in low power mixed-signal simulation. A power-smart connect module in AMS-CPF can:
- Identify and honor all possible methods of shutting off a power domain.
- Identify a change in the active state of a power domain as soon as the power mode transition occurs and read the voltage value from the associated nominal condition.
- Use the voltage value of a nominal condition associated with a power domain to perform the digital-to-analog transition.
Refer to the connect library in the installation to see the power-smart connect module definitions.