LOG112 Log Amp LTspice symbol.

L

Lostgallifreyan

Guest
This is the result of my work mentioned in the previous thread, subject:
'Subcircuit levels', and LTspice...

The first post in that thread has the unedited LOG112 model from Texas
Instruments. (Save it as LOG112.sub if you want it for LTspice, where it
will work as it is).

I decided to make a full diagram (copied from the datasheet and slightly
modified to save space) for the symbol to help me learn how to use the
device. That might help others as much as me, so here's the whole symbol
file. (Save as LOG112.asy for LTspice).

Version 4
SymbolType CELL
LINE Normal 138 28 128 24
LINE Normal 118 36 138 28
LINE Normal 138 44 118 36
LINE Normal 118 52 138 44
LINE Normal 138 60 118 52
LINE Normal 118 68 138 60
LINE Normal 128 72 118 68
LINE Normal 64 -48 64 -96
LINE Normal -76 -56 -88 -80
LINE Normal -88 -56 -40 -56
LINE Normal -52 -56 -40 -80
LINE Normal -64 -56 -64 128
LINE Normal -40 -80 -16 -80
LINE Normal -79 -71 -88 -80
LINE Normal -86 -67 -88 -80
LINE Normal 36 16 36 32
LINE Normal 28 24 44 24
LINE Normal 28 -24 44 -24
LINE Normal 20 -32 -16 -32
LINE Normal 20 32 0 32
LINE Normal 108 0 128 0
LINE Normal 108 0 20 -51
LINE Normal 20 51 108 0
LINE Normal 20 -51 20 51
LINE Normal 84 138 88 128
LINE Normal 76 118 84 138
LINE Normal 68 138 76 118
LINE Normal 60 118 68 138
LINE Normal 52 138 60 118
LINE Normal 44 118 52 138
LINE Normal 40 128 44 118
LINE Normal 128 128 128 72
LINE Normal 88 128 128 128
LINE Normal 228 16 228 32
LINE Normal 220 24 236 24
LINE Normal 220 -24 236 -24
LINE Normal 212 -32 192 -32
LINE Normal 212 32 160 32
LINE Normal 300 0 320 0
LINE Normal 300 0 212 -51
LINE Normal 212 51 300 0
LINE Normal 212 -51 212 51
LINE Normal -148 -56 -136 -80
LINE Normal -136 -56 -184 -56
LINE Normal -172 -56 -184 -80
LINE Normal -160 -56 -160 96
LINE Normal -184 -80 -288 -80
LINE Normal -145 -71 -136 -80
LINE Normal -138 -67 -136 -80
LINE Normal -88 -80 -136 -80
LINE Normal -252 16 -252 32
LINE Normal -260 24 -244 24
LINE Normal -260 -24 -244 -24
LINE Normal -268 -32 -320 -32
LINE Normal -268 32 -288 32
LINE Normal -180 0 -112 0
LINE Normal -180 0 -268 -51
LINE Normal -268 51 -180 0
LINE Normal -268 -51 -268 51
LINE Normal -112 -80 -112 0
LINE Normal -288 -80 -288 -32
LINE Normal -16 -80 -16 64
LINE Normal -288 32 -288 80
LINE Normal 0 32 0 80
LINE Normal -288 80 0 80
LINE Normal -320 64 -16 64
LINE Normal -160 96 128 96
LINE Normal -64 128 40 128
LINE Normal -96 80 -96 160
LINE Normal 128 -96 128 -80
LINE Normal 192 -96 192 -32
LINE Normal 0 128 0 160
LINE Normal -224 128 -192 128
LINE Normal -320 128 -272 128
LINE Normal -192 128 -192 160
LINE Normal 128 24 128 -48
LINE Normal 128 -80 160 -80
LINE Normal 160 -80 160 32
LINE Normal 64 -48 128 -48
RECTANGLE Normal 320 160 -320 -96
RECTANGLE Normal -224 144 -272 112
CIRCLE Normal -286 -30 -290 -34
CIRCLE Normal -110 -78 -114 -82
CIRCLE Normal -94 82 -98 78
CIRCLE Normal -14 -30 -18 -34
CIRCLE Normal 2 130 -2 126
CIRCLE Normal 130 98 126 94
CIRCLE Normal 130 2 126 -2
TEXT 8 152 Left 0 GND
TEXT 200 152 Left 0 V+
TEXT 264 152 Left 0 V-
TEXT -88 152 Left 0 Vcm
TEXT -184 152 Left 0 Vref GND
TEXT -312 120 Left 0 Vref
TEXT -312 56 Left 0 I2
TEXT -312 -40 Left 0 I1
TEXT 72 -88 Left 0 Vlog
TEXT 136 -88 Left 0 +In
TEXT 200 -88 Left 0 -In
TEXT 295 -8 Left 0 Out
TEXT 187 136 Left 0 Power Inputs
WINDOW 0 -208 -112 Center 0
WINDOW 3 -96 32 Center 0
SYMATTR Value LOG112
SYMATTR Prefix X
SYMATTR Description LOG112 Logarithmic Amplifier.
SYMATTR ModelFile LOG112.sub
PIN -320 -32 RIGHT 8
PINATTR SpiceOrder 1
PIN 128 -96 BOTTOM 8
PINATTR SpiceOrder 2
PIN 192 -96 BOTTOM 8
PINATTR SpiceOrder 3
PIN 64 -96 BOTTOM 8
PINATTR SpiceOrder 4
PIN 192 160 BOTTOM 8
PINATTR SpiceOrder 5
PIN 320 0 LEFT 8
PINATTR SpiceOrder 6
PIN -320 128 RIGHT 8
PINATTR SpiceOrder 7
PIN 256 160 BOTTOM 8
PINATTR SpiceOrder 8
PIN 0 160 TOP 8
PINATTR SpiceOrder 9
PIN -192 160 TOP 8
PINATTR SpiceOrder 10
PIN -96 160 TOP 8
PINATTR SpiceOrder 11
PIN -320 64 RIGHT 8
PINATTR SpiceOrder 12
 
A variant, more compact, and clearer for simple log converters like frequency
to pitch converters in synthesisers. It makes it easier to place other
symbols when 3 decades of dynamic range (about ten octaves worth) are enough.
Feed about 100ľA from Vref to I2, feed exponential voltage (proportional to
frequency) into I2 via a resistor (100K for Vmax of 10V), put compensation
capacitor between I2 and Vlog. The Vlog output is inverted so the standard
inverting op-amp can be made to invert, scale, and offset using Vref or other
voltage as offset source. it will all need tweaking and better understanding,
but if anyone finds this while looking for a LTspice circuit for electronic
music purposes, this could be a useful start. The LOG112 was the best way I
could find to do what Bob Moog did, with none of that awkward temeperature
compensation needed.

Version 4
SymbolType CELL
LINE Normal 138 28 128 24
LINE Normal 118 36 138 28
LINE Normal 138 44 118 36
LINE Normal 118 52 138 44
LINE Normal 138 60 118 52
LINE Normal 118 68 138 60
LINE Normal 128 72 118 68
LINE Normal 64 -64 64 -96
LINE Normal -60 -56 -72 -80
LINE Normal -72 -56 -24 -56
LINE Normal -36 -56 -24 -80
LINE Normal -48 -56 -48 128
LINE Normal -24 -80 0 -80
LINE Normal -63 -71 -72 -80
LINE Normal -70 -67 -72 -80
LINE Normal 36 16 36 32
LINE Normal 28 24 44 24
LINE Normal 28 -24 44 -24
LINE Normal 20 -32 0 -32
LINE Normal 20 32 0 32
LINE Normal 108 0 128 0
LINE Normal 108 0 20 -51
LINE Normal 20 51 108 0
LINE Normal 20 -51 20 51
LINE Normal 84 138 88 128
LINE Normal 76 118 84 138
LINE Normal 68 138 76 118
LINE Normal 60 118 68 138
LINE Normal 52 138 60 118
LINE Normal 44 118 52 138
LINE Normal 40 128 44 118
LINE Normal 128 128 128 72
LINE Normal 88 128 128 128
LINE Normal 196 16 196 32
LINE Normal 188 24 204 24
LINE Normal 188 -24 204 -24
LINE Normal 180 -32 160 -32
LINE Normal 180 32 160 32
LINE Normal 268 0 288 0
LINE Normal 268 0 180 -51
LINE Normal 180 51 268 0
LINE Normal 180 -51 180 51
LINE Normal -132 -56 -120 -80
LINE Normal -120 -56 -168 -56
LINE Normal -156 -56 -168 -80
LINE Normal -144 -56 -144 96
LINE Normal -168 -80 -272 -80
LINE Normal -129 -71 -120 -80
LINE Normal -122 -67 -120 -80
LINE Normal -72 -80 -120 -80
LINE Normal -236 16 -236 32
LINE Normal -244 24 -228 24
LINE Normal -244 -24 -228 -24
LINE Normal -252 -32 -272 -32
LINE Normal -252 32 -272 32
LINE Normal -164 0 -96 0
LINE Normal -164 0 -252 -51
LINE Normal -252 51 -164 0
LINE Normal -252 -51 -252 51
LINE Normal -96 -80 -96 0
LINE Normal -272 -80 -272 -32
LINE Normal 0 -96 0 -32
LINE Normal -272 32 -272 80
LINE Normal 0 32 0 80
LINE Normal -272 80 0 80
LINE Normal -144 96 128 96
LINE Normal -48 128 40 128
LINE Normal -96 80 -96 160
LINE Normal 160 -96 160 -32
LINE Normal 0 128 0 160
LINE Normal -208 128 -192 128
LINE Normal -288 128 -240 128
LINE Normal -192 128 -192 160
LINE Normal 128 24 128 -64
LINE Normal 160 32 160 160
LINE Normal 64 -64 128 -64
LINE Normal -192 -96 -192 -80
RECTANGLE Normal 288 160 -288 -96
RECTANGLE Normal -208 144 -240 112
CIRCLE Normal -190 -78 -194 -82
CIRCLE Normal -94 -78 -98 -82
CIRCLE Normal -94 82 -98 78
CIRCLE Normal 2 -78 -2 -82
CIRCLE Normal 2 130 -2 126
CIRCLE Normal 130 98 126 94
CIRCLE Normal 130 2 126 -2
TEXT 8 152 Left 0 GND
TEXT 264 64 Left 0 V+
TEXT 264 128 Left 0 V-
TEXT -88 152 Left 0 Vcm
TEXT -184 152 Left 0 Vref GND
TEXT -280 120 Left 0 Vref
TEXT 8 -88 Left 0 I2
TEXT -184 -88 Left 0 I1
TEXT 72 -88 Left 0 Vlog
TEXT 168 152 Left 0 +In
TEXT 168 -88 Left 0 -In
TEXT 263 -8 Left 0 Out
WINDOW 0 -96 -112 Center 0
WINDOW 3 -96 32 Center 0
SYMATTR Value LOG112
SYMATTR Prefix X
SYMATTR Description LOG112 Logarithmic Amplifier.
SYMATTR ModelFile LOG112.sub
PIN -192 -96 RIGHT 8
PINATTR SpiceOrder 1
PIN 160 160 BOTTOM 8
PINATTR SpiceOrder 2
PIN 160 -96 BOTTOM 8
PINATTR SpiceOrder 3
PIN 64 -96 BOTTOM 8
PINATTR SpiceOrder 4
PIN 288 64 BOTTOM 8
PINATTR SpiceOrder 5
PIN 288 0 LEFT 8
PINATTR SpiceOrder 6
PIN -288 128 RIGHT 8
PINATTR SpiceOrder 7
PIN 288 128 BOTTOM 8
PINATTR SpiceOrder 8
PIN 0 160 TOP 8
PINATTR SpiceOrder 9
PIN -192 160 TOP 8
PINATTR SpiceOrder 10
PIN -96 160 TOP 8
PINATTR SpiceOrder 11
PIN 0 -96 RIGHT 8
PINATTR SpiceOrder 12
 
You must log in or register to reply here.

Welcome to EDABoard.com

Sponsor

Back
Top