Research And Design Of 14-bit 4 GS/s Digital-to-analog Converter Based On SiGe HBT Process

The development of advanced communication systems has increased the demands for the speed and accuracy of digital-analog conversion circuit.DACs along with ADCs,serve as a bridge between the analog and digital worlds,are crucial to the development of various fields,including high-speed data communication,premium test instruments,and radar systems.Therefore,it is necessary to research and develop high-speed and high-precision DACs.This article proposes a high-speed and high-precision DAC with sampling rate of 4 GHz and resolution of 14 bits.The proposed DAC is designed based on Hua Hong Hong Li’s 0.18μm SiGe BiCMOS process.All circuits in this design are built by SiGe heterojunction bipolar transistors to meet the high-speed data processing speed of 4 GHz.Compared with complementary metal-oxide-semiconductor logic circuits,HBT digital circuits based on current mode logical have higher power consumption and larger chip area overhead.Therefore,this article uses a 10+4 segment decoding method.The LSB 10-bit current-steering DAC uses an R-2R ladder resistor network to achieve binary-weighted current output,and the MSB 4-bit uses 15 units of current sources to generate thermometer current-steering DAC output.In order to reduce the pressure of high sampling rate exert on input data rate,this DAC uses a 2:1 multiplexer to synthesize two low-rate data into one high-rate data.The data interface uses low-voltage differential signal circuits that are widely used in signal transmission fields to achieve better anti-electromagnetic interference performance.This article uses Cadence Virtuoso IC6.1.8 to complete the schematic and layout design of the entire circuit.The simulation results show that the designed DAC’s DNL and INL are 0.54 LSB and0.39 LSB respectively,and its SFDR can reach 80 dBc or more in the entire Nyquist frequency domain.Under mixed power supply of 3.3V and 5V,the average power consumption of the entire DAC is 2.39 W.The total layout area of the DAC is 11.22 mm~2.