| 摘要 |
The invention provides a two-output low-noise down converter circuit which is improved in the isolation between two outputs. In the two-output low-noise down converter circuit, an input signal is divided into two divisional signals of different polarization systems and then the divisional two signals are processed by two-system signal processing circuits which comprise low-noise amplifiers 2a, 2b, band-pass filters 3a, 3b, frequency converter circuits 5a, 5b and a local oscillator 4, respectively. The two-output low-noise down converter circuit includes: a switching circuit 11 for performing switching control on the outputs of the two signal processing circuits responsive to the voltages applied to two output terminals 8a, 8b, and for selectively outputting two polarized signals to its output terminals; intermediate frequency amplifiers 12a, 12b for amplifying the two outputs of the switching circuit 11 and leading out the resulting outputs at the two output terminals 8a, 8b; and a control circuit 9 for controlling the turning-on and -off of the power of the intermediate frequency amplifiers 12a, 12b responsive to loads of the two output terminals 8a, 8b. <IMAGE> |
