Mixed IO types
*
* This circuit contains a mixture of IO types, including
* analog, digital, user-defined (real), and 'null'.
*
* The circuit demonstrates the use of the digital and
* user-defined node capability to model system-level designs
* such as sampled-data filters.  The simulated circuit
* contains a digital oscillator enabled after 100us.  The
* square wave oscillator output is divided by 8 with a
* ripple counter.  The result is passed through a digital
* filter to convert it to a sine wave.
*
.tran 1e-5 1e-3
*
v1 1 0 0.0 pulse(0 1 1e-4 1e-6)
r1 1 0 1k
*
abridge1 [1] [enable] atod
.model atod adc_bridge
*
aclk [enable clk] clk nand
.model nand d_nand (rise_delay=1e-5 fall_delay=1e-5)
*
adiv2 div2_out clk NULL NULL NULL div2_out dff
adiv4 div4_out div2_out NULL NULL NULL div4_out dff
adiv8 div8_out div4_out NULL NULL NULL div8_out dff
.model dff d_dff
*
abridge2 div8_out enable filt_in node_bridge2
.model node_bridge2 d_to_real (zero=-1 one=1)
*
xfilter  filt_in clk filt_out  dig_filter
*
abridge3 filt_out a_out node_bridge3
.model node_bridge3 real_to_v
*
rlpf1 a_out oa_minus 10k
*
xlpf  0 oa_minus lpf_out  opamp
*
rlpf2 oa_minus lpf_out 10k
clpf  lpf_out oa_minus 0.01uF
*
*
.subckt  dig_filter  filt_in clk filt_out
*
.model n0 real_gain (gain=1.0)
.model n1 real_gain (gain=2.0)
.model n2 real_gain (gain=1.0)
.model g1 real_gain (gain=0.125)
.model zm1 real_delay
.model d0a real_gain (gain=-0.75)
.model d1a real_gain (gain=0.5625)
.model d0b real_gain (gain=-0.3438)
.model d1b real_gain (gain=1.0)
*
an0a filt_in x0a n0
an1a filt_in x1a n1
an2a filt_in x2a n2
*
az0a x0a clk x1a zm1
az1a x1a clk x2a zm1
*
ad0a x2a x0a d0a
ad1a x2a x1a d1a
*
az2a x2a filt1_out g1
az3a filt1_out clk filt2_in zm1
*
an0b filt2_in x0b n0
an1b filt2_in x1b n1
an2b filt2_in x2b n2
*
az0b x0b clk x1b zm1
az1b x1b clk x2b zm1
*
ad0 x2b x0b d0b
ad1 x2b x1b d1b
*
az2b x2b clk filt_out zm1
*
.ends dig_filter
*
*
.subckt  opamp  plus minus out
*
r1 plus minus 300k
a1 %vd (plus minus) outint lim
.model lim limit (out_lower_limit = -12 out_upper_limit = 12
+             fraction = true  limit_range = 0.2  gain=300e3)
r3 outint out 50.0
r2 out 0 1e12
*
.ends opamp
*
*
.end