An embodiment of the invention provides a single-ended polar transmitting circuit. The single-ended polar transmitting circuit comprises a DAC, a differential-to-single-ended converter, a GmC filter and a load. The GmC filter comprises two gain stages, two filters, two switching devices, a translinear loop and a current mirror. When a second clock signal is high, a first current is conducted through the load, a second switching device and a second gain stage. When a first clock signal is high, a second current is conducted through a first switching device and the second gain stage. The first gain stage has a transconductance Gm1 and the second gain stage has a transconductance Gm2. The bandwidth of the GmC filter is approximately equal to the square root of the quantity (Gm1*Gm2)/(C1*C2). The bandwidth of the GmC filter is substantially a constant value.