Abstract: A receiver optical subassembly for transforming received optical signal into electrical signal includes at least a ceramic substrate, a photo receiver and a transimpedance amplifier. There are high-speed traces formed on the substrate. The positive and negative pads of the photo receiver are coplanar and connected to the traces without wire bonding so as to reduce the parasitic impedance effect and improve the high-speed performance of the optical subassembly. The transimpedance amplifier is electrically connected to the traces via flip chip, wire bonding or other methods. The photo receiver and the transimpedance amplifier are connected via the high-speed traces formed on the substrate.