| *-------------------------------- |
| * Complete Digital PLL testbench |
| *-------------------------------- |
| |
| .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 "digital_pll.spice" |
| |
| .option TEMP=27 |
| * .option RELTOL=1.0E-2 |
| |
| * Instantiate the digital PLL |
| |
| X0 vdd vss reset osc clkp1 clkp0 div4 div3 div2 div1 div0 digital_pll |
| |
| * Power supply (note that all logic is 1.8V here) |
| |
| V0 vdd vss PWL(0.0 0.0 25n 1.8) |
| V1 vss 0 0.0 |
| |
| * Fixed divider value (connect resistors to power or ground) |
| * divider value = 16 (10MHz * 16 = 160MHz clock) |
| |
| R0 div4 vdd 1 |
| R1 div3 gnd 1 |
| R2 div2 gnd 1 |
| R3 div1 gnd 1 |
| R4 div0 gnd 1 |
| |
| * Run oscillator at 10MHz |
| * Because DFFs don't handle reclocking well, keep the edges sharp. |
| |
| V2 osc vss PULSE(0.0 1.8 5n 10p 10p 50n 100n) |
| |
| * Reset pulse |
| V3 reset vss PWL(0.0 1.8 0.1u 1.8 0.101u 0.0) |
| |
| * Transient analysis. Note that trim updates every four cycles, or about |
| * three updates per microsecond. To update all 17 trim bits requires |
| * 6us. |
| |
| .control |
| tran 1n 8u |
| plot V(osc) |
| plot V(clkp0) V(clkp1) |
| .endc |
| .end |
