The switching and routing of analog signals is a fundamental part of signal processing, but not one that is easily implemented if accuracy and precision are required. This chapter focuses on audio applications, but the basic parameters such as isolation and linearity are equally relevant in many fields.
A mechanical switch normally makes a solid unequivocal connection when it is closed, and it is as ‘on’ as the resistance of its contacts and connections allows; these are small fractions of an ohm and are unlikely to cause trouble in small-signal audio design. Switches are, however, in general terms a good deal less ‘off’. The insulation resistance may be measured in petaohms, but what does the damage ...