A Practical Approach to the Design of an S-Band Image-Rejecting Dual-Conversion Super-Heterodyne RF Chain of a Receiver Considering Spur Signals

TL;DR

This paper proposes a practical design method for an S-band superheterodyne RF receiver that effectively mitigates spur signals, enhancing the spurious-free dynamic range through innovative MATLAB-based techniques and optimized component selection.

Contribution

It introduces a novel MATLAB-based approach for spur signal mitigation in superheterodyne RF chains, applicable to various mixers and configurations, improving dynamic range performance.

Findings

The method significantly reduces spur signals and improves SFDR.

Designed RF filters lower implementation costs.

Validated results with microwave software and full-wave analysis.

Abstract

This paper presents a typical design of the RF section of a radar receiver, the chain within a superheterodyne dual-conversion architecture. A significant challenge in this framework is the occurrence of spur signals, which negatively impact the dynamic range of the RF chain. When addressing this issue, the paper introduces an innovative approach to mitigate (or even wipe out) these undesired effects, utilizing two mutually verifying MATLAB codes. These codes have been tested with two distinct commercial mixers and could be applied to any superheterodyne configuration with various mixers. The presented method makes the Spurious-Free Dynamic Range (SFDR) of the chain the least different from the dynamic range of the chain. Also, the selection of other components gets optimized to align with spurious signals consideration, with explanations provided for these choices. Moreover, two filters of the RF chain, the second and the third, have been designed to reduce implementation costs. Various Microwave software and full-wave analyses were employed for detailed design and analysis, with the results compared to evaluate their performance.