017_jitter_noise : Noise Jitter influences
Requires: SmartSpice & Smartview
Minimum Versions: SMARTSPICE 4.6.5.R
A simple 9 Stage inverting Ring Oscillator is used with an external N element noise source injected through a capacitor to show jitter sensitivity in the ring oscillator output. The input deck input deck contains .TRAN NOISE and .MEASURE analysis.
Rubberband the C2 device capacitance [cap] parameter to see the influence of injecting a different noise level on the performance and EYE diagram of the node v(x20.cn1) and you will see with no external noise source waveforms and with the injected noise waveforms visable.
Input Files
9_stage_ring_plus_noise.in
** 9 Stage Ring Oscillator + injected N element Noise
*******************************************************cs
.ic cn23='vsupply/2'
.param vsupply=3.3
.global 0 vcc
**.include "./Pch.M"
**.include "./Nch.M"
.include "./pmos.model"
.include "./nmos.model"
** Subcircuit: Inverter
.subckt Inverter ip_inv op_inv
C1 ip_inv 0 10f
R1 cn19 op_inv r=10.0m
R2 op_inv cn20 r=10.0m
M1 cn20 ip_inv 0 0 Nch w=5u l=1.2u
M2 vcc ip_inv cn19 vcc Pch w=10u l=1.2u
.ends Inverter
** Subcircuit: 9 Stage Ring
.subckt 9stage_inverter_block in out
R3 in cn1 r=2
R4 cn2 cn3 r=2
R5 cn4 cn5 r=2
R6 cn6 cn7 r=2
R7 cn8 cn9 r=2
R8 cn10 cn11 r=2
R9 cn12 cn13 r=2
R10 cn14 cn15 r=2
R11 cn16 cn17 r=2
R12 cn18 out r=2
X1 cn1 cn2 Inverter
X2 cn3 cn4 Inverter
X3 cn5 cn6 Inverter
X4 cn7 cn8 Inverter
X5 cn9 cn10 Inverter
X6 cn11 cn12 Inverter
X7 cn13 cn14 Inverter
X8 cn15 cn16 Inverter
X9 cn17 cn18 Inverter
.ends 9stage_inverter_block
** Buffer output from ring
.subckt buffer_stage in_buf out_buf
M1 cn30 in_buf 0 0 Nch w=5u l=1.2u
M2 vcc in_buf cn30 vcc Pch w=10u l=1.2u
M3 out_buf cn30 0 0 Nch w=10u l=1.2u
M4 vcc cn30 out_buf vcc Pch w=20u l=1.2u
.ends buffer_stage
** Main Circuit
X20 cn27 cn23 9stage_inverter_block
X21 cn23 cn24 buffer_stage
**V0 cn27 0 pulse( 0.0 vsupply 0.0 1.5e-9 1.5e-9 8e-9 20e-9)
R1 cn27 cn23 1
C0 cn49 0 c=2p
R2 cn24 cn49 r=100
V1 vcc 0 dc=vsupply
** Noise element
N cn28 0 SW=1.6632e-21
C2 cn28 cn27 0.2pF
.save V(cn27) V(cn27)
.TRAN 10p 1u Jitter NOISE noiseseed=1 noisefmax=5e9 noisescale=1.0
.measure PPvoltage PP v(SM) FROM=0n TO=1u
.measure RMSvoltage RMS v(SM) FROM=0n TO=1u
*.tran 0.1n 300n
.save v(x20.cn1) v(x20.cn3) v(x20.cn5) v(x20.cn7) v(x20.cn9)
.save v(x20.cn11) v(x20.cn13) v(x20.cn15) v(x20.cn17) v(x20.cn18)
.save v(x21.cn23) v(x21.cn24)
.save all(v)
.end
Graphics
