bag3_digital.design.stdcells.inv.beta

Module Contents

Classes

InverterBetaDesigner

An inverter design script that sizes the PMOS to have equal pull-up and pull-down strengths.

Functions

parse_params_file(→ bag.util.immutable.Param)

Returns the parsed parameter file if a Pathlike argument is specified, otherwise passthrough is performed.
bag3_digital.design.stdcells.inv.beta.parse_params_file(params: Union[Mapping[str, Any], str, pathlib.Path]) → bag.util.immutable.Param[source]

Returns the parsed parameter file if a Pathlike argument is specified, otherwise passthrough is performed.

Parameters:

params (Union[Mapping[str, Any], str, Path]) – The parameters to parse. If a string or a Path, then it is assumed to be the path to a yaml file and its contents are returned.

Returns:

new_params – the parsed parameters cast to an immutable dictionary.

Return type:

Param

class bag3_digital.design.stdcells.inv.beta.InverterBetaDesigner(root_dir: pathlib.Path, sim_db: bag.simulation.cache.SimulationDB, dsn_specs: Mapping[str, Any])[source]

Bases: bag.simulation.design.DesignerBase

An inverter design script that sizes the PMOS to have equal pull-up and pull-down strengths. The NMOS size is specified directly by the user or the generator specs. The PMOS-to-NMOS ratio (beta) is returned.

Parameters:

dsn_specs (Mapping[str, Any]) –

The design script specifications. The following entries should be specified:

gen_specsUnion[Mapping[str, Any], Path, str]

The base/default generator parameters. For each design iteration, new generator parameters will be computed by overriding only the transistor sizing. If a Path or str is specified, the argument will be treated as a path to a specs YAML file.

meas_paramsMapping[str, Any]

The InvMeas parameters.

beta_minfloat

The minimum PMOS-to-NMOS ratio. Defaults to 0.25.

beta_maxfloat

The maximum PMOS-to-NMOS ratio. Defaults to 4.

seg_nint

Optional. Specify to override the number of NMOS segments in gen_specs.

property dut_class: Union[Type[bag.layout.template.TemplateBase], Type[bag.design.module.Module]][source]
classmethod get_dut_gen_specs(is_lay: bool, base_gen_specs: bag.util.immutable.Param, gen_params: Mapping[str, Any]) → bag.util.immutable.Param[source]

Compute the new generator parameters by modifying the base parameters.

Parameters:

  • is_lay (bool) – True if DUT generator is a layout generator, False if schematic generator.

  • base_gen_specs (Param) – The base/default generator specs.

  • gen_params (Mapping[str, Any]) – The variable names and values to override in base_gen_specs.

Returns:

output – The new generator specs.

Return type:

Param

classmethod get_seg_n(is_lay: bool, gen_specs: bag.util.immutable.Param) → int[source]

Return the number of NMOS segments specified in the generator parameters.

Parameters:

  • is_lay (bool) – True if DUT generator is a layout generator, False if schematic generator.

  • gen_specs (Param) – The generator specs.

Returns:

output – The number of NMOS segments

Return type:

int

commit()[source]

Commit changes to specs dictionary. Perform necessary initialization.

async async_design(beta_min: float = 0.25, beta_max: float = 4, **kwargs: Any) → Mapping[str, Any][source]

A coroutine that designs an inverter with equal pull-up and pull-down. This is done with a binary search on the PMOS sizing.

Parameters:

  • beta_min (float) – The minimum PMOS-to-NMOS ratio.

  • beta_max (float) – The maximum PMOS-to-NMOS ratio.

Returns:

output – The design results. Contains the following entries:

seg_pint

The number of PMOS segments.

seg_nint

The number of NMOS segments.

betafloat

The PMOS-to-NMOS ratio.

delay_error_avgfloat

The delay mismatch.

Return type:

Mapping[str, Union[np.ndarray, int]]

static get_seg_p_size_bounds(seg_n: int, beta_min: float, beta_max: float) → Tuple[int, int][source]

Compute the bounds for number of PMOS segments.

Parameters:

  • seg_n (int) – The number of NMOS segments.

  • beta_min (float) – The minimum PMOS-to-NMOS ratio.

  • beta_max (float) – The maximum PMOS-to-NMOS ratio.

Returns:

output – The range of number of PMOS segments, specified as (min size, max size).

Return type:

Tuple[int, int]

async measure_dut(sim_id: str, dut: bag.simulation.design.DesignInstance) → Mapping[str, Any][source]

A coroutine that measures the delay mismatch between the output rise and fall.

Parameters:
Returns:

output – The measurement results. Contains the following entries, in addition to the ones specified in InvMeas:

delay_errornp.ndarray

The error between pull-up delay and pull-down delay, normalized by the pull-down delay.

delay_error_avgfloat

The average normalized delay error across all corners and simulation sweeps.

Return type:

Mapping[str, Any]