An 0.2 THz brodband unbalanced doubler multiplier was designed and realized based on four anodes in anti-series GaAs planar Schottky diodes. The Schottky diode was flip-chiped on the 75 ?滋m thick quartz. The circuit output power and efficiency was measured under the condition of small and large input power. The measured efficiency was bigger than 3% over the band of 210 GHz to 224 GHz with the input power between 10 mW to 15 mW under the condition of forward bias voltage. The peak efficiency is 7.8% at the frequency of 212 GHz. The measured efficiency was bigger than 3.6% over the band of 210 GHz to 224 GHz with the input power between 48 mW to 88 mW under the condition of self-biased. The peak efficiency is 5.7% at the frequency of 214 GHz. The biggest output power is 5.7 mW and 7.5 mW at the fixed frequency of 212 GHz when the input power is 132 mW under the condition of self-biased and reverse bias voltage of -0.8 V separately.