Because of the need for a large market and the initial problems with technically complex circuits, integrated circuits developed later for analogue than for digital systems. There are now two reasonably distinct groups of analogue circuits, namely those for professional use and those for incorporation in consumer equipment.In the former category characteristics and trends of professional circuits are considered with particular reference to operational amplifiers and other types of amplifier, voltage regulators, analogue multipliers and phase-locked loops. Consumer integrated circuits considered include audio amplifiers, radio receivers and allied devices, and circuits for colour television. In all cases there is a tendency for monolithic designs to diverge from established circuit practice in discrete technology, and this trend may be expected to continue.