A High Speed DAC Design And Simulation Using InP-DHBT

DAC is a digital-to-analog signal converter, which links the digital and analog world. With the rapid development of modern electronic system, higher speed DAC is required. For special advantages, InP(Indium Phosphide)DHBT(Double Heterojunction Bipolar Transistors) devices received prominent attention to the field of high-speed DAC in recent years.Basic working principle of DAC is discussed and fundamental operating principle, layer design, device models of InP-DHBT components are elaborated in this paper. Based on the basic knowledge, one kind the current-steering circuit is proposed by using InP-DHBT, the circuit has a temperature-decoding circuit composing of binary decoding logic and ROM, instead of the traditional decoding arrays circuit. By using this circuit, the speed of DAC can be enhanced by a large scale, and at the same time the size and costs can be reduced effectively.According to the circuit structure, this thesis gives the DAC design using InP DHBT. The DHBT is developed by Fraunhofer IAF in Germany which has the emitter area of 4 um2, the fT and fmax above 260GHz. design and simulation of analog and digital circuit are carried out respectively, then whole circuit simulation is accomplished. Results show that, the circuit can achieve 10GSPS the working rate, INL is 0.036LSB and DNL is 0.019LSB for static characteristics, and SFDR is 33.92dB for dynamic characteristics under the 6V single power supply.