Phase change switch which switches between four phase positions

摘要

The switch can be switched into four positions to change phase between 0,90,180 and 270 degrees. The switch includes a directional coupler (3) to which the signal to be phase shifted is fed. The direct and coupled outputs (6,8) of the coupler are each selectively fed via a change-over switch (7,9) to a cut-off resistor (Z). Alternatively they are fed via a further change-over switch (12) to the inverting (17) or non-inverting (13) input of an operational amplifier (16). The phase shifted signal is provided at the output (19) of the operational amplifier. The phase change circuit is pref. used in a wideband 360 degree phase shifter. The phase change switch is connected in a chain with an all-pass filter (2) which is continually adjustable between at least +45 degrees, and -45 degrees, phase displacement.