We designed the on-chip antenna combined with coplanar waveguide (CPW) broadband impedance matching circuit and duplexers with BPFs. Firstly, we designed a slot antenna with a radiation resistance matched to a three-pole bandpass filter (BPF) with 10.5GHz center frequency and 8% fractional bandwidth. Next, in order to obtain the high isolation from transmitter (Tx) to receiver (Rx), we attached the phase control line, which can be used as impedance matching, in front of each BPF in a duplexer. Finally, we design the Tx-and Rx-BPF matched to the input impedance of the antenna and phase control line. In the duplexer, Rx 2-pole BPF has center frequency=10.3GHz and bandwidth=40MHz, and Tx BPF has center frequency=10.7GHz and bandwidth=40MHz.