Convention Paper
Analogue-to-Digital and Digital-to-Analogue Converters for High Quality Sound
AES Convention 65 · Paper 1583 · February 1980
Abstract
The BBC has been using digital systems for high-quality sound since 1972, when a digital sound-in-syncs system was introduced into the television distribution network. In the same year, p.c.m. links started to replace analogue music circuits in the radio network. These early digital transmission systems employ analogue-to-digital and digital-to-analogue converters of the ramp-counter type developed within the BBC; converters with 10-bit resolution are used in the sound-in-syncs system, with analogue companding, and 13-bit converters in the radio p.c.m. system. Since these digital systems were introduced, the need for higher-resolution a.d.cs. and d.a.cs for use in future transmission systems and studio applications (e.g. digital recording equipment and mixers) has been recognised. Difficulties experienced with high-resolution ramp-counter designs have led the BBC to study conversion using the ladder-network d.a.c. technique and the successive-approximation a.d.c. technique. The paper to be presented describes 16-bit analogue-to-digital and digital-to-analogue converters of the floating-point type, embodying a commercial successive-approximation a.d.c. and ladder-network d.a.c. with relatively low resolution, which have been developed at BBC Research Department.
