US Patent 7457337 Optical module having case grounding using bypass capacitor

According to embodiments of the present invention, an optical transponder includes a transmitter optical subassembly (TOSA). In one embodiment, the electrical ground of the TOSA may be DC-isolated from chassis ground of the transponder using a blocking capacitor that couples the AC signal path to VDD and that allows the case of the TOSA to float. In an alternative embodiment, the electrical ground of the TOSA may be DC-isolated from chassis ground of the transponder using a blocking capacitor that couples the AC signal path to VDD and a resistor that couples the DC bias level path to internal electrical ground or transponder case ground.