On-wafer scattering parameter characterization of differential four-port networks LNA using two-port vector network analyzer

This paper presents a technique that enables very accurate measurement for S-parameter of differential low noise amplifier by means of a standard two-port vector network analyzer (VNA). This technique involves by terminating two ports at one time while another two ports are measured. Accurate characterization of a two port device requires a four-port vector network analyzer, which might be not easily available. Thus, it is a common practice to terminate the two of the four ports to be used which the conventional/standard two port VNA. Even though the above approach is applicable but the reliability and conformity of the test method is still limited and uncertain. For verification, the measurement using four-port VNA have been conducted to test the devices S-parameters are accurately similar with the two port network. The fabricated on-wafer differential LNA structure was tested and measured with normal two-port VNA and also four-port VNA. By using this technique, there is no need to purchase a four-port VNA. By using this technique, any multi-port circuit network can be measured. The LNA has been implemented in RF 0.13um CMOS process. The differential LNA shows the measured performance in term of gain is equal to 17.4 dB. This give the percentage difference of 0.63 compared with measured using four-port VNA. The circuit consume only 9 mW power while dissipating 7.59mA from a 1.8 V supply. Generally, the measured results of the on-wafer fabricated differential LNA show good agreement for both set up.