Abstract : The AD9857 is a high-performance digital quadrature upconverter launched by Analog Devices. This paper introduces the system structure and working principle of the AD9857 and presents its application in a radar echo simulation generation system. Digital upconversion based on DSP and AD9857 features a simple structure, good versatility, and high reliability. It can meet the upconversion processing requirements of various modulation signals, and can change the modulation mode of the digital baseband signal and the radar's operating parameters in real time, achieving programmability of radar operating parameters. Keywords : Digital upconverter, AD9857, Principle and Application 1. Main Performance of AD9857 The AD9857 is a 14-bit integral digital upconverter launched by Analog Devices. The AD9857 has an internal clock speed of 2 (X) MHz, integrates a 4-20x programmable clock multiplier with a lock-in indicator, and provides a high-precision system clock; single-ended or differential input reference clock. Input clock range 10-50MHz; 14-bit DUC and DA data channels, integrating two interpolation filters and a CIC pre-compensation filter, accepting composite FQ data input; the maximum 90MHz carrier output can be generated by the 14-bit frequency control word; the orthogonal carrier provided by the DDS can realize up-conversion modulation of various signals such as PAM, QAM, ASK, and FSK; 10MHz serial communication control interface, compatible with SPI; 8-bit output amplitude control; good dynamic output characteristics, when outputting a 65MHz analog signal, its spurious-free dynamic range (SFDR) is greater than 80dB. [b]2 System Structure and Working Principle of AD9857 2.1 System Structure of AD9857[/b] The system structure of AD9857 is shown in Figure 1. It mainly consists of a 14-bit parallel data input interface, a CIC inversion filter, a fixed interpolation factor filter, a CIC programmable interpolation filter, an orthogonal modulator, a direct digital frequency generator (DDS), an inverted SINC filter, a 14-bit DAC, a serial communication port, internal registers, and a clock circuit. 2.2 Working Principle [b][align=center]For details, please click: The Principle and Application of the AD9857 Digital Quadrature Upinverter[/align][/b]