We are a group of students working on ultrasound imaging system. The transducer we use outputs current signals. So we need high speed transimpedance amplifiers. AD8015 TIA came to our attention. However, when we tested it by simply wiring it up like said in the datasheet and giving no input current signal, AD8015 TIA has unexplained 3.8V output voltage offset in channel 1 output and around 2.8V output voltage offset in channel2. Datasheet shows only negative offsets. Could you explain why this is the case? We have brought two such chips and they all behave the same way.