Tv-if circuit

Abstract

TV-IF circuit comprising a balanced video signal path (A.sub.5, M, A.sub.6, VM) arranged between an IF-input (1, 1') and a video signal output (2, 2') and a balanced sound signal path (A.sub.1, A.sub.2, A.sub.7, SM) arranged between the IF-input (1, 1') and a sound signal output (3, 3'), these two paths comprising a video mixing stage (VM) and a sound mixing stage (SM), respectively for a quasi-parallel sound signal processing or an intercarrier sound signal processing. The compatability between these two modes of sound signal processing increases the range of applications compared with prior art TV-IF circuits and this is accomplished by a matrix circuit (M) comprising a balanced, non-inverting (5, 5') and a balanced, inverting (4, 4') input, as well as a balanced output (6, 6'), the matrix circuit (M) being included via the non-inverting input (5, 5') and the output (6, 6') in one (A.sub.5, M, A.sub.6, VM) of said two signal paths (A.sub.5, M, A.sub.6, VM or A.sub.1, A.sub.2, A.sub.7, SM) between the IF-input (1, 1') and a signal input (7, 7') of the mixing stage (VM) in this signal path (A.sub.5, M, A.sub.6, VM), the other signal path (A.sub.1, A.sub.2, A.sub.7 SM) between the IF-input (1, 1') and a signal input (10, 10') of the mixing stage (SM) in the last-mentioned signal path (A.sub.1, A.sub.2, A.sub.7, SM) being connected to the balanced, inverting input (4, 4') of the matrix circuit (M) and comprising between the IF-input (1, 1') and the matrix circuit (M) a balanced first pair of terminals (9, 9') which may optionally be shortcircuited, remain open-circuited or for connecting therebetween a resonant circuit (FSC) having a resonant frequency which corresponds to a sound carrier frequency of the TV-IF signal applied to the IF-input.