I need to get reinstated so I can upload circuits --there has to be a way the moderators of this forum can look me up! I had to open a new account because I changed jobs and can’t remember my old password!!! I’ll try pasting the netlist here, including the model.
Basically, when PD\ is connected to +5V, I get this
"Warning: Singular matrix. Check nodes 113•X1 and 2•X1
Pseudo transient analysis failed at t=0
Fatal error: Pseudo transient analysis failed to find the operating point.
" in Qspice. I recreated the circuit in LTspice and it worked without issues.
I do not get the singular matrix warning or the error if PD\ is grounded.
I tried setting “.options gmin=1e-12”, and also connecting PD\ through a 100Meg resistor to +5V, but still got the same error. I appreciate some pointers here.
- C:\for_help_in_forum.qsch
X1 N01 N02 +5V 0 1Stage1_out +5V ADA4841
C5 N05 N04 82nF
R8 N04 N03 18.2K
C6 N03 0 750pF
R9 N03 N02 9.09K
R10 0 N01 27.4K
C8 N02 1Stage1_out 330p
R11 N03 1Stage1_out 18.2K
V7 N05 0 1 ac=1
V1 +5V 0 5
.ac dec 1000 0.01 10Meg
.end
the model for the ADA4841:
*ADA4841 Macro-model
*Function:Amplifier
*
*Revision History:
*Rev.x Oct 2015-ZZ
*Copyright 2015 by Analog Devices
*
*Refer to http://www.analog.com/Analog_Root/static/techSupport/designTools/spicemodels/license
*for License Statement. Use of this model indicates your acceptance
*of the terms and provisions in the License Staement.
*
*Tested on MultSIm, SiMetrix(NGSpice), PSpice
*
*Not modeled: Distortion, PSRR, Overload Recovery,
-
Shutdown Turn On/Turn Off time
*Parameters modeled include:
- Vos, Ibias, Input CM limits and Typ output voltge swing over full supply range,
- Open Loop Gain & Phase, Slew Rate, Output current limits, Voltage & Current Noise over temp,
- Capacitive load drive, Quiescent and dynamic supply currents,
- Shut Down pin functionality where applicable,
- Single supply & offset supply functionality.
*Node Assignments
-
Non-Inverting Input -
| Inverting Input -
| | Positive supply -
| | | Negative supply -
| | | | Output -
| | | | | PD -
| | | | | |
.Subckt ADA4841 100 101 102 103 104 106
*#ASSOC Category=“Op-Amps” symbol=opamp_6_pd
Power Supplies
Rz1 102 1020 Rideal 1e-6
Rz2 103 1030 Rideal 1e-6
Ibias 1020 1030 dc 0.04e-3
DzPS 98 1020 diode
Iquies 1020 98 dc 1.16e-3
S1 98 1030 106 113 Switch
R1 1020 99 Rideal 1e7
R2 99 1030 Rideal 1e7
e1 111 110 1020 110 1
e2 110 112 110 1030 1
e3 110 0 99 0 1
*
*
Inputs
S2 1 100 106 113 Switch
S3 9 101 106 113 Switch
VOS 1 2 dc 40e-6
IbiasP 110 2 dc 3e-6
IbiasN 110 9 dc 3e-6
RinCMP 110 2 Rideal 180e6
RinCMN 9 110 Rideal 180e6
CinCMP 110 2 1.5e-12
CinCMN 9 110 1.5e-12
IOS 9 2 0.1e-6
RinDiff 9 2 Rideal 25e3
CinDiff 9 2 3e-12
*
*
Non-Inverting Input with Clamp
g1 3 110 110 2 0.001
RInP 3 110 Rideal 1e3
RX1 40 3 Rideal 0.001
DInP 40 41 diode
DInN 42 40 diode
VinP 111 41 dc 1.46
VinN 42 112 dc 0.36
*
*
Vnoise
hVn 6 5 Vmeas1 707.10678
Vmeas1 20 110 DC 0
Vvn 21 110 dc 0.65
Dvn 21 20 DVnoisy
hVn1 6 7 Vmeas2 707.10678
Vmeas2 22 110 dc 0
Vvn1 23 110 dc 0.65
Dvn1 23 22 DVnoisy
*
*
Inoise
FnIN 9 110 Vmeas3 0.7071068
Vmeas3 51 110 dc 0
VnIN 50 110 dc 0.65
DnIN 50 51 DINnoisy
FnIN1 110 9 Vmeas4 0.7071068
Vmeas4 53 110 dc 0
VnIN1 52 110 dc 0.65
DnIN1 52 53 DINnoisy
*
FnIP 2 110 Vmeas5 0.7071068
Vmeas5 31 110 dc 0
VnIP 30 110 dc 0.65
DnIP 30 31 DIPnoisy
FnIP1 110 2 Vmeas6 0.7071068
Vmeas6 33 110 dc 0
VnIP1 32 110 dc 0.65
DnIP1 32 33 DIPnoisy
*
*
CMRR
RcmrrP 3 10 Rideal 1e12
RcmrrN 10 9 Rideal 1e12
g10 11 110 10 110 -1e-10
Lcmrr 11 12 1e-12
Rcmrr 12 110 Rideal 1e3
e4 5 3 11 110 1
*
*
Power Down
VPD 111 80 dc 1.89
VPD1 81 0 dc 0.42
RPD 111 106 Rideal 0.769e6
ePD 80 113 82 0 1
RDP1 82 0 Rideal 1e3
CPD 82 0 1e-10
S5 81 82 83 113 Switch
CDP1 83 0 1e-12
RPD2 106 83 1e6
*
*
Feedback Pin
*RF 105 104 Rideal 0.001
*
*
VFB Stage
g200 200 110 7 9 1
R200 200 110 Rideal 250
DzSlewP 201 200 DzSlewP
DzSlewN 201 110 DzSlewN
*
*
Dominant Pole at 50 Hz
g210 210 110 200 110 1.2566e-6
R210 210 110 Rideal 3183.1e6
C210 210 110 1e-012
*
*
Output Voltage Clamp-1
RX2 60 210 Rideal 0.001
DzVoutP 61 60 DzVoutP
DzVoutN 60 62 DzVoutN
DVoutP 61 63 diode
DVoutN 64 62 diode
VoutP 65 63 dc 5.109
VoutN 64 66 dc 5.109
e60 65 110 111 110 1.086
e61 66 110 112 110 1.086
*
*
Pole at 128MHz
g220 220 110 210 110 0.001
R220 220 110 Rideal 1000
C220 220 110 1.2434e-12
*
Buffer
g230 230 110 220 110 0.001
R230 230 110 Rideal 1000
*
Buffer
g240 240 110 230 110 0.001
R240 240 110 Rideal 1000
*
Buffer
g245 245 110 240 110 0.001
R245 245 110 Rideal 1000
*
Buffer
g250 250 110 245 110 0.001
R250 250 110 Rideal 1000
*
Buffer
g255 255 110 250 110 0.001
R255 255 110 Rideal 1000
*
Buffer
g260 260 110 255 110 0.001
R260 260 110 Rideal 1000
*
Buffer
g265 265 110 260 110 0.001
R265 265 110 Rideal 1000
*
Buffer
g270 270 110 265 110 0.001
R270 270 110 Rideal 1000
*
Notch: f=110MHz, Zeta=2, Gain=2.6dB
e280 280 110 270 110 1
R280 280 285 Rideal 10
L280 285 281 13.983e-9
C280 281 282 149.715e-12
R281 282 110 Rideal 28.656
*
Buffer
e290 290 110 285 110 1
R290 290 292 Rideal 10
e295 295 110 292 110 1
*
*
Output Stage
g300 300 110 295 110 0.001
R300 300 110 Rideal 1000
e301 301 110 300 110 1
Rout 302 303 Rideal 43
Lout 303 310 80e-9
Cout 310 110 8e-12
*
*
Output Current Limit
H1 301 304 Vsense1 100
Vsense1 301 302 dc 0
VIoutP 305 304 dc 2.336
VIoutN 304 306 dc 5.336
DIoutP 307 305 diode
DIoutN 306 307 diode
Rx3 307 300 Rideal 0.001
*
*
Output Clamp-2
VoutP1 111 73 dc 0.69
VoutN1 74 112 dc 0.69
DVoutP1 75 73 diode
DVoutN1 74 75 diode
RX4 75 310 Rideal 0.001
*
*
Supply Currents
FIoVcc 314 110 Vmeas8 1
Vmeas8 310 311 dc 0
R314 110 314 Rideal 1e9
DzOVcc 110 314 diode
DOVcc 102 314 diode
RX5 311 312 Rideal 0.001
FIoVee 315 110 Vmeas9 1
Vmeas9 312 313 dc 0
R315 315 110 Rideal 1e9
DzOVee 315 110 diode
DOVee 315 103 diode
*
*
Output Switch
S4 104 313 106 113 Switch
*
*
*** Common Models ***
.model diode d(bv=100)
.model Switch vswitch(Von=0.425,Voff=0.415,ron=0.001,roff=1e6)
.model DzVoutP D(BV=4.3)
.model DzVoutN D(BV=4.3)
.model DzSlewP D(BV=9.273)
.model DzSlewN D(BV=9.273)
.model DVnoisy D(IS=1.67e-16 KF=3.26e-17)
.model DINnoisy D(IS=7.39e-17 KF=3.69e-16)
.model DIPnoisy D(IS=7.39e-17 KF=3.69e-16)
.model Rideal res(T_ABS=-273)
*
.ends ADA4841