A low-cost approach for testing embedded rf passive circuits based on oscillation principle

In this paper, a low-cost method for testing RF passive filters embedded in an RF substrate is proposed. As compared to a conventional test method the proposed method reduces the test-setup cost by around 35%. This method does not require any vector network analyzer (VNA) and allows the testing of embedded RF filters without any external test stimulus. A calibration technique is presented for an efficient implementation of the proposed method at the production floor. The core principle of the method is to include embedded passive filters through substrate surface probes into an external RF amplifier located on the probe card, such that this inclusion causes the RF amplifier to oscillate. RF filters are tested by measuring the changes in the oscillation frequency of the proposed test-setup. Hence, the test-setup cost reduces substantially. The test method with the calibration technique is demonstrated by simulations and measurements.