A 4 Gbps transmitter for a 12-bit 250 MSPS pipelined ADCs is presented.A low power current mode(CM) output driver with reverse scaling technique is proposed.A high speed,low power combined serializer is implemented to convert 12 bit parallel data into a serial data stream.The whole transmitter is used in a 12-bit250 MSPS pipelined ADC for the digital output buffer and fabricated in 180 nm 1.8 V 1P5M CMOS technology.Test results show that the transmitter provides an eye height greater than 800 mV for data rates of both 2 Gbps and 4 Gbps,the 12-bit 250 MSPS ADC achieves the SNR of 69.92 dBFS and SFDR of 81.17 dB with 20.1 MHz input at full sampling speed.The ADC with the 4 Gbps transmitter consumes the power consumption of 395 mW,where the power consumption of transmitter is 75 mW.The ADC occupies an area of 2.5×3.2 mm~2,where the active area of the transmitter block is 0.5×1.2 mm~2. A 4 Gbps transmitter for a 12-bit 250 MSPS pipelined ADCs is presented. A low power current mode (CM) output driver with reverse scaling technique is proposed. A high speed, low power combined serializer is implemented to convert 12 bit parallel data into a serial data stream. The whole transmitter is used in a 12-bit 250 MSPS pipelined ADC for the digital output buffer and fabricated in 180 nm 1.8 V 1P5M CMOS technology. Test results show that the transmitter provides an eye height greater than 800 mV for data rates of both 2 Gbps and 4 Gbps, the 12-bit 250 MSPS ADC achieves the SNR of 69.92 dBFS and SFDR of 81.17 dB with 20.1 MHz input at full sampling speed. The ADC with the 4 Gbps transmitter consumes the power consumption of 395 mW , where the power consumption of the transmitter is 75 mW. The ADC occupies an area of ​​2.5 × 3.2 mm ~ 2, where the active area of ​​the transmitter block is 0.5 × 1.2 mm ~ 2.