Low-noise tape preamplifier with new self-biasing architecture

A low-noise ground-compatible preamplifier for audio signal processing is presented. It amplifies the audio signal coming from a magnetic head producing a total input-referred voltage noise less than 300-nV r.m.s. CCIR/ARM weighted in operative conditions thanks to a low-noise bipolar amplifier, while auto-reverse, metal/normal, and mute facilities are available on chip using low-noise offset-free analog CMOS switches. Total harmonic distortion was less than 0.004% in full dynamic range. This performance was obtained using a nonconventional self-biasing ground-compatible preamplifier architecture, particularly intended for single supply applications, that does not require any external components and auxiliary voltage reference. The preamplifier occupies 1.5 mm² and dissipates 38 mW with a 10-V power supply. A measured power supply rejection of about 120 dB at 1 kHz was obtained using internal regulated voltage supply.