I suggest you don't mention any figure for two reasons:
1. Since you are in a small company, your current CTC would likely be below their average—so what you ask will have to be way beyond your present CTC, and the HR person is sure to find ways to refuse it.
2. In case you perform very well in the interviews, why foreclose your options until then by mentioning any figure?
So, I suggest mentioning 'open' or 'as per company norms' until the stage comes for this aspect to be discussed seriously.
Regards,
TS