Added digital (xspice) example code to examples/cmos/

examples/cmos/cmos_cells_digital.sp

@@ -0,0 +1,31 @@
+
+.SUBCKT BUF A Y
+.model buffer1 d_buffer
+Abuf A Y buffer1
+.ENDS NOT
+
+.SUBCKT NOT A Y
+.model not1 d_inverter
+Anot A Y not1
+.ENDS NOT
+
+.SUBCKT NAND A B Y
+.model nand1 d_nand
+Anand [A B] Y nand1
+.ENDS NAND
+
+.SUBCKT NOR A B Y
+.model nor1 d_nor
+Anand [A B] Y nor1
+.ENDS NOR
+
+.SUBCKT DLATCH E D Q
+.model latch1 d_latch
+Alatch D E null null Q nQ latch1
+.ENDS DLATCH
+
+.SUBCKT DFF C D Q
+.model dff1 d_dff
+Adff D C null null Q nQ dff1
+.ENDS DFF
+

examples/cmos/testbench.sh

@@ -5,3 +5,6 @@ set -ex
 ../../yosys counter.ys
 ngspice testbench.sp
 
+# requires ngspice with xspice support enabled:
+#ngspice testbench_digital.sp
+

examples/cmos/testbench.sp

@@ -9,8 +9,8 @@ Vdd Vdd 0 DC 3
 .MODEL cmosp PMOS LEVEL=1 VT0=-0.7 KP=50U GAMMA=0.57 LAMBDA=0.05 PHI=0.8
 
 * load design and library
-.include synth.sp
 .include cmos_cells.sp
+.include synth.sp
 
 * input signals
 Vclk clk 0 PULSE(0 3 1 0.1 0.1 0.8 2)

examples/cmos/testbench_digital.sp

@@ -0,0 +1,35 @@
+
+* supply voltages
+.global Vss Vdd
+Vss Vss 0 DC 0
+Vdd Vdd 0 DC 3
+
+* simple transistor model
+.MODEL cmosn NMOS LEVEL=1 VT0=0.7 KP=110U GAMMA=0.4 LAMBDA=0.04 PHI=0.7
+.MODEL cmosp PMOS LEVEL=1 VT0=-0.7 KP=50U GAMMA=0.57 LAMBDA=0.05 PHI=0.8
+
+* load design and library
+.include cmos_cells_digital.sp
+.include synth.sp
+
+* input signals
+Vclk clk 0 PULSE(0 3 1 0.1 0.1 0.8 2)
+Vrst rst 0 PULSE(0 3 0.5 0.1 0.1 2.9 40)
+Ven  en  0 PULSE(0 3 0.5 0.1 0.1 5.9 8)
+
+Xuut dclk drst den dout0 dout1 dout2 counter
+* Bridge to digital
+.model adc_buff adc_bridge(in_low = 0.8 in_high=2)
+.model dac_buff dac_bridge(out_high = 3.5)
+Aad [clk rst en] [dclk drst den] adc_buff
+Ada [dout0 dout1 dout2] [out0 out1 out2] dac_buff
+
+
+.tran 0.01 50
+
+.control
+run
+plot v(clk) v(rst)+5 v(en)+10 v(out0)+20 v(out1)+25 v(out2)+30
+.endc
+
+.end