A Digitally Controllable Attenuator with an Accuracy of 0.2dB over 1-30GHz Based on a 16-bit Digital-to-Analog Converter

In order to meet the needs of fine resolution of attenuation in such applications as high accuracy multi-channel calibration and vector-modulators, a broadband attenuator with a digitally controllable step as fine as 0.2dB based on a 16-bit digital-to-analog converter (DAC) is proposed in this paper. The high-precision DAC generates an analog voltage with a resolution of up to 1mV, which is used to accurately control two cascaded voltage variable attenuator (VVA) chips. A prototype of the digitally controllable attenuator is designed and tested. Measurement results demonstrate that the proposed digitally controllable attenuator exhibit an attenuation range more than 34dB and attenuation accuracy of 0.2dB over 1-30GHz as bias voltage changed from -1V to 0V in steps of a couple of millivolts.