A low-cost test method for embedded RF passive circuits using two-tone input signals

Abstract

In the last decade, substantial research has been preformed for designing RF passive filters for embedding them in RF substrates to miniaturize RF front-ends. However, little work has been done to test these embedded RF passive filters at low-cost. Currently, embedded RF filters are tested by performing highfrequency (GHz) measurements using costly instruments such as Vector Network Analyzers (VNAs) on the production floor. Since the test cost of RF substrates with embedded RF filters can be substantial, there is a need for low-cost methods for testing such embedded filters. In this paper, a low-cost method is proposed that enables the testing of embedded RF filters by using two-tone input signals and regression analysis. This method eliminates the use of VNAs for production-level testing of RF filters and also enables testing of high-frequency (GHz) passive filters at MHz frequencies. In this test method, insertion loss of a RF filter at high frequencies (in GHz range) is predicted from low-frequency response (in MHz range) of the proposed test setup using regression analysis. Thus, the test-setup cost reduces significantly. The proposed test method is demonstrated with both simulations and measurements.