A 2–4 GHz transceiver front-end is implemented in 0.18-μm COMS technology for S-band digital array radar (DAR) applications. An improved tri-directional RF amplifier (TDRA) without single pole double throw (SPDT) switch is applied in the RF port and wideband matching from 2 to 4 GHz is achieved. While an improved tri-directional IF amplifier (TDIA) without SPDT switch is applied in the IF port and wideband matching from 300 to 800 MHz is achieved. At 2–4 GHz, the front-end shows gain of 21–28 dB and the noise figure of 9–11.5 dB in RX, while gain of 17–20 dB in TX. The output P-1dB achieves 14.5 dBm and 9 dBm for RX and TX respectively. The RX IR is 35–45 dB at 2–4 GHz. The chip size is 3.2×2 mm2 including pads.