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from __future__ import annotations
from typing import Any, Mapping, Optional, Sequence, cast
from pathlib import Path
import numpy as np
import matplotlib.pyplot as plt
from bag.simulation.cache import SimulationDB, DesignInstance
from bag.simulation.measure import MeasurementManager
from bag.simulation.data import SimData
from bag.concurrent.util import GatherHelper
from ..sp.base import SPTB
from ..data.tran import get_first_crossings, EdgeType
[docs]class MOSSPMeas(MeasurementManager):
[docs] async def async_meas_pvt(self, name: str, sim_dir: Path, sim_db: SimulationDB, dut: Optional[DesignInstance],
harnesses: Optional[Sequence[DesignInstance]], pvt: str) -> Mapping[str, Any]:
# add port on G and D using dcblock
load_list = [dict(pin='gport', nin='s', type='port', value={'r': 50}, name='PORTG'),
dict(pin='gport', nin='g', type='dcblock', value=''),
dict(pin='dport', nin='s', type='port', value={'r': 50}, name='PORTD'),
dict(pin='dport', nin='d', type='dcblock', value=''),
]
# add DC bias using dcfeed
load_list.extend([dict(pin='gbias', nin='s', type='vdc', value='vgs'),
dict(pin='gbias', nin='g', type='dcfeed', value=''),
dict(pin='dbias', nin='s', type='vdc', value='vds'),
dict(pin='dbias', nin='d', type='dcfeed', value=''),
])
# set vgs and vds sweep info
vds_val = self.specs['vds_val']
vgs_val = self.specs['vgs_val']
tbm_specs = dict(
**self.specs['tbm_specs'],
load_list=load_list,
sim_envs=[pvt],
swp_info=[('vds', dict(type='LIST', values=vds_val)),
('vgs', dict(type='LIST', values=vgs_val))],
dut_pins=dut.pin_names,
param_type='Y',
ports=['PORTG', 'PORTD'],
)
tbm = cast(SPTB, self.make_tbm(SPTB, tbm_specs))
sim_results = await sim_db.async_simulate_tbm_obj(name, sim_dir, dut, tbm, {'dut_conns': {'b': 's', 'd': 'd',
'g': 'g', 's': 's'}},
harnesses=harnesses)
results = calc_ft_fmax(sim_results.data)
return results
[docs]def calc_ft_fmax(sim_data: SimData) -> Mapping[str, Any]:
freq = sim_data['freq']
y11 = sim_data['y11']
y12 = sim_data['y12']
y21 = sim_data['y21']
y22 = sim_data['y22']
# calculate fT: freq where h21 reaches 1
h21 = y21 / y11
ft = get_first_crossings(freq, np.abs(h21), 1, etype=EdgeType.FALL)
# calculate fmax: freq where unilateral gain U reaches 1
_num = np.abs(y21 - y12) ** 2
_den = 4 * (y11.real * y22.real - y12.real * y21.real)
ug = _num / _den
fmax = get_first_crossings(freq, ug, 1, etype=EdgeType.FALL)
return dict(ft=ft[0], fmax=fmax[0], vgs=sim_data['vgs'], vds=sim_data['vds'])
[docs]def plot_results(results: Mapping[str, Any]) -> None:
vgs = None
vds = None
fig, (ax0, ax1) = plt.subplots(1, 2)
ax0.set(xlabel='vgs (V)', ylabel='fT (GHz)', title='fT vs vgs')
ax1.set(xlabel='vgs (V)', ylabel='fmax (GHz)', title='fmax vs vgs')
for sim_env, _results in results.items():
if vgs is None:
vgs = _results['vgs']
vds = _results['vds']
for idx, _vds in enumerate(vds):
ax0.plot(vgs, _results['ft'][idx] * 1e-9, label=f'vds={_vds}, {sim_env}')
ax1.plot(vgs, _results['fmax'][idx] * 1e-9, label=f'vds={_vds}, {sim_env}')
ax0.legend()
ax1.legend()
plt.tight_layout()
plt.show()