A filter circuit includes a polyphase filter coupled to a first circuit component and a second circuit component. The first circuit component propagates four input current signals to the polyphase filter. The third and fourth input current signals are substantially one-hundred-eighty degrees out of phase with the first and second input current signals. The polyphase filter receives the input current signals and generates four output current signals that are out of phase with each other. The second circuit component generates first and second output signals using the four output current signals. The first and second output signals are ninety degrees out of phase with each other.