GB1072440A - Improvements in varactor up-converters - Google Patents

Abstract

1,072,440. Parametric frequency changers. G. & E. BRADLEY Ltd. Dec. 31, 1965 (Jan. 1, 1965], No. 36/65. Heading H3B. In a varactor up-converter in which a wide separation between the input signal and upper side band frequencies gives theoretical high gain, the loss of efficiency due to the filters required is reduced by the use of two or more varactor stages, the output of each stage constituting the input of the next stage and the pumping frequencies of successive stages being progressively higher. As shown, the input signal (60 Mc/s.) at terminals 21 is fed through a low-pass filter 22 to the first varactor stage 24, where it is mixed with the first-stage pump signal (150 Mc/s.) fed through a stop filter 25 centred on the input signal frequency. The intermediate output signal (210 Mc/s.) produced by the first stage is fed through a band-pass filter 26 centred on the intermediate signal frequency of the second varactor stage 27. Here it is mixed with the second stage pump signal (450 Mc/s.) which is supplied through a stop filter 31 centred on the intermediate signal frequency. The second stage pump signal may be derived by a multiplier circuit 30 from the first stage pump signal source 23. The final output signal (660 Mc/s.) is taken from the second stage through a band-pass filter 32 centred on the output signal frequency.