| *--------------------------------------------------------------------------- |
| * SPDX-FileCopyrightText: 2020 Efabless Corporation |
| * Licensed under the Apache License, Version 2.0 (the "License"); |
| * you may not use this file except in compliance with the License. |
| * You may obtain a copy of the License at |
| * |
| * https://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| * |
| * SPDX-License-Identifier: Apache-2.0 |
| *--------------------------------------------------------------------------- |
| * Ring oscillator testbench---simple check of ring oscillator |
| * at several trim levels |
| |
| .lib "/home/tim/projects/efabless/tech/SW/sky130A/libs.tech/ngspice/sky130.lib.spice" tt |
| |
| .include "/home/tim/projects/efabless/tech/SW/sky130A/libs.ref/sky130_fd_sc_hd/spice/sky130_fd_sc_hd.spice" |
| |
| .include "ring_osc2x13.spice" |
| |
| .option TEMP=27 |
| * .option RELTOL=1.0E-1 |
| * .option RSHUNT=1.0E20 |
| |
| * Instantiate the ring oscillator |
| * Tie trims together in four sets |
| |
| X0 vdd vss clockp0 clockp1 reset trim0 trim1 trim0 trim1 trim0 trim1 trim0 |
| + trim1 trim0 trim1 trim0 trim1 trim0 trim3 trim2 trim3 trim2 trim3 trim2 |
| + trim3 trim2 trim3 trim2 trim3 trim2 trim3 ring_osc2x13 |
| |
| * Power supply (note that all logic is 1.8V here) |
| |
| V0 vdd vss PWL(0n 0.0 30n 1.8) |
| V1 vss 0 0.0 |
| |
| * Trim values (connect resistors to power or ground) |
| * divider value = 12 |
| |
| V2 trim0 gnd PULSE(0.0 1.8 200n 2n 2n 1u 2u) |
| V3 trim1 gnd PULSE(0.0 1.8 400n 2n 2n 1u 2u) |
| V4 trim2 gnd PULSE(0.0 1.8 600n 2n 2n 1u 2u) |
| V5 trim3 gnd PULSE(0.0 1.8 800n 2n 2n 1u 2u) |
| |
| * Reset |
| V6 reset gnd PWL(0n 1.8 48n 1.8 50n 0.0) |
| |
| * Transient analysis |
| .control |
| tran 100p 1u |
| plot V(clockp0) V(clockp1) |
| .endc |
| .end |
