Local Oscillator

The design of the LO chains follows the experience gained during the development of the Herschel/HIFI Local Oscillators. A synthesizer signal in the range of 11 – 18 GHz is first multiplied by a factor of 6 to generate 1 mW RF power at the input of the W-band power amplifier provided by JPL. The amplifier produces up to 250 mW of RF signal power and drives the cascaded tuner-less frequency multiplier stages which are cooled to 120K. In the 450 μm channel a doubler/doubler/doubler combination is used, whereas a doubler/doubler/tripler cascade generates the output in the 350 μm channel. To cover the wide tuning range of the 350 μm channel, two LO-chains are necessary. A rotary mirror selects between these two LO signals.

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