Wideband automatic level control circuit for wideband signal generator application

This paper presents the design and implementation of the output power control circuit for a signal generator from 3GHz to 6GHz, which is achieved with automatic level control (ALC) technique using voltage variable attenuator. The performance of the ALC loop is simulated and optimized by using commercial EDA software. The digital control system consisting of PC, MCU and DAC is designed to calibrate the output power of ALC by calibration routine. The testing results indicate that the ALC loop circuit possesses good performance within the operating frequency range from 3GHz to 6GHz, the input dynamic range as large as 28dB and the output power variation lower than 0.1dB. The measured results show that the developed ALC loop circuit is good enough to be applied into the output power control for signal generator in microwave frequency band.