Broadband switch using deactivated crosspoints for establishing switching paths.

摘要

A broadband space switch matrix constructed from a plurality of NAND gates (10-70) arranged into a set of cascaded stages to form a tree-switch multiplexing configuration. A plurality of input digital signals are applied to input ports (1-4) coupled to the NAND gates (10, 20, 30, 40, respectively) in the first stage (No. 1). A selected one of the input signals (A) emerges as an output signal (A) from an output port (74) coupled to a single NAND gate (70) in the last stage (No. 3). Each NAND gate (10) has a select line (SEL11) for receiving control signals. The switching path for the selected input signal is established by placing the sequence of NAND gates (20, 50, 70) defined by the selected switching path in a state of conduction whereby only the selected input signal propagates through the switch. This is effected by forcing to a HIGH state the particular NAND gates in each stage whose outputs are coupled to the same NAND gate in the following stage along with the output of the NAND gate in the current stage which is in the chosen path. The forced HIGH state is achieved by applying a LOW state signal to the respective select lines of these particular NAND gates (10 and 60). In an alternate arrangement, the NAND gates in the first stage (No. 1) are replaced by 2:1 pass-transistor-selectors which offer a reduction in the number of transistors.