The entire Sigma Designs chip business – with the exception of its Z-Wave low power IoT network chips – seems to have evaporated since the December announcement that it was being sold to Silicon Labs. At the time, the entire business was valued at $282 million, and now the Z-Wave business on its own will actually change hands for $240 million. That places an enterprise value on the rest of Sigma of around $42 million which, given that its last results show it has over $60 million in the bank, means that all the other designs are seen as worthless. This week the share price fell to $7, yielding a market capitalization of $271 million. The company said that after…