Calibration-Free Return Loss Measurement System based on ADL6010

CN-0387, Application circuit measures return loss in a wireless transmitter from 1 GHz to 28 GHz without any need for system calibration. The design is implemented on a single circuit board using a nonreflective RF switch, a microwave RF detector and a 12-bit, precision analog-to-digital converter (ADC). To evaluate the circuit over the widest possible frequency range, a dual-port directional coupler with SMA connectors was used instead of a narrow-band, surface-mount directional coupler. The circuit measures return loss of up to 20 dB over an input power range of 25 dB (return losses in excess of 20 dB can be measured over a smaller input power range)