GB959443A - Improvements in or relating to parametric amplifiers - Google Patents

Abstract

959,443. Parametric amplifiers. COMPAGNIE GENERALE TELEGRAPHIE SANS FIL. July 1, 1960 [July 6, 1959], No. 23086/60. Heading H3B. A parametric amplifier comprises two hybrid junctions 1, 6, having two pairs of arms 3, 4; 7, 10 connected by lines 15, 16 containing non- linear crystal diodes 11, 12; filters 17, 18 and 21, 22 being arranged to block the pump frequency and filters 19, 20 and 23, 24 being arranged to block the signal frequency. The signal input and signal output are connected to arms 2, 5 respectively of hybrid 1 and the arms 8, 9 of hybrid 6 are respectively connected to the pump source and to a dummy load. With arms of hybrids 1, 6 being arranged to introduce 90 degrees phase shift and the signal and pump frequencies respectively it can be shown that the combined incident energy reaching a hybrid from the lines 15, 16 is channeled wholly to the output 5 or the dummy load 9, as the case may be, none reaching either the input 2 or the source 8, so that instability caused by reflections due to mismatch is avoided. Filters such as 17, 18 are preferably open-circuited lines of length equal to an odd multiple of “ of the pump wavelength (#p) separated by a distance equal to an odd multiple of “ of the signal wavelength (#s). Filters such as 19, 20 have these dimensions interchanged. The lines 15, 16 and the filter lines are preferably of the threelayer sandwich type and may be printed circuits.