In this paper, a diplexer circuit to separate GSM from CDMA band is designed using a LTCC (Low Temperature Cofired Ceramic) multi-layer technology. In order to increase a integration capability of the diplexer, it is designed using 3-dimensional (3-D) multi-layer compact inductor and capacitors in e-layer LTCC substrate with a relative dielectric constant of 7. In order to achieve high selectivity of the bands, a shunt capacitor and inductor are designed in the high-pass filter (HPF) and low-pass filter (LPF), respectively. The size of the fabricated diplexer including CPW pads is 3,450 ${ imes}$4,000 ${ imes}$694 ${mu}m^3$An insertion loss (IL) and return loss in GSM band are less than -1.35dB and more than -5.66dB,respectively. In the case of CDMA band, the IL of -1.54dBandRLof above -9.30dBare archived.