In the process of using the microwave frequency down-converter,the local oscillation circuit is easily affected by undulate temperature,so center frequency of local oscillation circuit will depart with the undulate temperature.In order to solve this problem,the temperature control circuit which is designed with the devices AD581 and AD590 keeps the temperature constant on inside of microwave frequency down-converter GSD2D3D.Experiment shows that method can solve the problem effectively and it has important ...