Channel coupling

Claim 1

A channel coupling circuit for use in controlling the coupling of signals between two separate channels including a first transistor for connection in a gain producing mode in a first channel, a second transistor for connection in a gain producing mode in a second channel, a first and a second electrode of each transistor being connected in a respective output signal current carrying path, an input terminal for each channel being connected directly to a third electrode of the transistor in that channel, an output terminal for each channel being connected directly to said first electrode of the transistor in that channel, a first impedance directly coupling said two first electrodes, a second impedance directly coupling said two second electrodes, one of said first and second impedances being variable, and a further impedance being connected to each first electrode in the respective output signal current carrying path, the relationship between the values of said first, second and further impedances determining the gains produced by said transistors between the input and output terminals in each channel and between the input terminal in one channel and the output terminal in the other channel and therefore the degree of coupling between the signals applied to the input terminals and the signals obtained from the output terminals of each channel.