Abstract : This paper proposes a digital downconversion method based on the CORDIC algorithm. First, the basic principle of the CORDIC algorithm is introduced, and then the implementation of the CORDIC algorithm in the local digital voltage-controlled oscillator (NCO) for digital downconversion is discussed. Due to the adoption of the algorithm-to-structure mapping idea, the algorithm can be successfully implemented on an FPGA and has been verified in practice. Keywords : CORDIC algorithm, digital downconverter, digital voltage-controlled oscillator, FPGA 1 Introduction In digital downconverters, the input signal is often divided into I and Q components, which are multiplied by the orthogonal COS and sin signals generated by the local digital oscillator (NCO) and then low-pass filtered to achieve downconversion. Using DDS (Direct Digital Frequency Synthesizer) to generate orthogonal signals COS and sin in the local digital oscillator of traditional digital downconverters has advantages such as ease of implementation (as shown in Figure 1), but it has disadvantages such as spurious emissions due to phase truncation and the need for certain ROM resources. This paper proposes a method to generate orthogonal sin and cosine signals using the CORDIC (Coordinate Rotation Digital Computer) algorithm to realize a digital down-converter (as shown in Figure 2). This method offers advantages such as high processing speed, high accuracy, minimal resource requirements, and low ROM. Since CORDIC employs iterative computation, its design can be optimized and its speed improved through various methods, which is highly advantageous in the design of certain VLSI chips. 2. CORDIC Algorithm Principle CORDIC is synonymous with a coordinate rotation computer, a type of computer proposed by Voider in 1959, primarily used in scientific calculators to calculate trigonometric functions, hyperbolic functions, and the modulus of vectors. J. Wahher proposed a unified, improved CORDIC algorithm in 1971. The following only introduces the basic principle of implementing orthogonal trigonometric functions cosine and sin using the CORDIC algorithm. [b][align=center]For more details, please click: Digital Down-Converter Based on CORDIC Algorithm[/align][/b]