Hi AG,
I forgot to mention that there is an A-device OTA (single ended unfortunately)
look LTspice\lib\sub folder at the UniversalOpamps2.sub file
it is a text netlist file, with an example of how to use the OTA
e.g.
A1 2 1 0 0 0 0 out 0 OTA G={Avol/Rout} ref={Vos} linear Cout={Cout}
+ en={en} enk={enk} in={in} ink={ink} incm={incm} incmk={incmk}
+ Vhigh=1e308 Vlow=-1e308 Rout={Rout}
R5 2 3 {2*Rin} noiseless
R6 1 4 {2*Rin} noiseless
R1 3 1 {2*Rin} noiseless
R2 2 4 {2*Rin} noiseless
.param Rout=.1
.param Cout={Avol/GBW/2/pi/Rout}
.param Avol=1Meg GBW=10Meg Slew=10Meg ilimit=25m rail=0 Vos=0
.param en=0 enk=0 in=0 ink=0 incm=0 incmk=0 Rin=1G
regards
Robert
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--- In LTspice@..., "RobertTalty" <rtalty@...> wrote:
Hi AG,
I would caution against using a simple E source based fully differential amp model. Usually G source with appropriate resistor results in a much better behaved model.
I believe I suggested you download some ADC models. within that ADC collection are some fully differential CMOS opamp / OTA models.
For a very simple model I would use
.subckt ideal_differential_op_amp Vinm Vinp Outp VCM Outm
R1 Outp N001 1
R2 N001 Outm 1
G1 N001 Outp Vinp Vinm 100MEG
G2 Outm N001 Vinp Vinm 100MEG
G3 0 N001 VCM N001 100MEG
.ends ideal_differential_op_amp
you can also include output caps to limit the bandwidth and change the resistor values to model the output impedance.
I cant give you the exact models I use at work because they don't really belong to me.
regards
Robert
--- In LTspice@..., "Apparajan" <dg1@> wrote:
I am re-posting this since I din't get a boo or an aye or nay..
Cheers
AG
--- In LTspice@..., "Apparajan" <dg1@> wrote:
I have uploaded my model
Temp-->File-->>E_model_for_diffamp.asc
It is a very simple model that models the differential and common mode loop gains. I have other more complicated models that model slew-rate, bandwidth, etc. However my most complicated model seems to be much simpler than what is commercially available? They also have a disclimer that they don't model offset, psrr, cmrr etc.? What gives...
