INA118 common mode voltage range and design issue of current monitor with 3v sup

[basantab]

Hello
the circuit below is for monitoring current level.

It works if i supply INA118 with more than 3 volt(in my case i supplied 9 volt and also works with lower than that as well).

My curiosity is with Common Mode Voltage Range. Can someone validate whether or not i am saying or doing right ?

So using circuit below i have sense resistor which dissipate around 0.1 mv and ina118 is amplifying and comparing it with comparator.
The voltage input on negative leg is 4.5 volt and positive leg is around 4.6 volt.  (if i am right) according to INA118 datasheet CMVR if(vcc-1 to gnd+1.1) which gives me the space of high 2 volt to low 1.1 volt (with vcc of 3 volt) common mode voltage input and cmvr is average of two inputs meaning i can input average signal of 1.1 volt to 2 volt (?).  But in my case both leg gets at least 4.5 volt meaning it exceeds the CMVR and output is not linear (am i right). So can there be in-amp which can take input(average) of higher than vcc or supply volt..

the problem is it goes into the circuit which has 3 volt supply (lets say no-boost conv for now)... and also the constant current generator is lm334 which requires at least more than 3 volt to produce cc into load of 15k ohm or more. Is there any ICs that takes 3 volt or less and can produce CC of 300ua into 15k or more load (i know mathematically it sounds awkward but if there is any magical way then it would be nice :-)


Can anyone validate that i am doing it right ? (personally i want to try current shunt monitors if this doesnot work).

thankyou so much for reading all this..

[basantab]

And also i have tried inputting voltage more than common mode voltage or average voltage on both more than (vcc-1volt in case of ina118) and the output is nonlinear.