Title :
Fully Integratable Class-AB Rear-End with Smart Quiescent Current Control for a General-Purpose Hearing Aid Chip
Author :
van der Woerd, Albert C. ; Serdijn, Wouter A. ; Davidse, Jan ; Van Roermund, Arthur H M
Author_Institution :
Delft University of Technology, Faculty of Electrical Engineering, Mekelweg 4, 2628 CD Delft, The Netherlands. phone +31-15-781579, fax: +31-15-785922, e-mail: A.C.vdWoerd@et.tudelft.nl
Abstract :
In this paper, the core of the rear-end of an universally applicable analog hearing aid chip is described. It contains, apart from some subcircuits, a current-level Class-AB controlled preamplifier with three independent gain controls and a novel half-switching bridged final amplifier for various hearing aid receivers from low-power up to medium-power. To minimize supply current, the quiescent current of the amplifier string is optimized at any value of the input current and the controlled gain by a translinear quiescent current processor. Chip area in a 2.5-¿m BiCMOS process amounts to 2.6 mm2. Measured THD remains below 2% in all cases (1kHz). The bandwidth is ≫12kHz. All circuits operate correctly with a battery voltage down to 1.05V. Total current drain (without input signal) varies between 140¿A and 425¿A.
Keywords :
Auditory system; Bandwidth; Battery charge measurement; BiCMOS integrated circuits; Current control; Current supplies; Gain control; Preamplifiers; Semiconductor device measurement; Voltage;
Conference_Titel :
Solid-State Circuits Conference, 1995. ESSCIRC '95. Twenty-first European
Conference_Location :
Lille, France
Print_ISBN :
2-86332-180-3
