A 1-V Class-AB Translinear Integrator for Filter Applications

In this paper, the design and measurements of a 1-volt class-AB instantaneous companding translinear integrator are presented. The use of instantaneous companding and class-AB operation gives an improvement of the dynamic range and a reduction of the power consumption. The proposed circuit uses only bipolar transistors and one capacitor and is, therefore, very well suited for integrated implementation. Its unity-gain frequency can easily be controlled by a current. Simulations and measurements of a semicustom realization, to be applied in a hearing instrument, confirm correct operation of the designed circuit. The translinear integrator operates from a single supply voltage down to 0.95 V. The current consumption is less than 1.9 A for an input current of 180 nA (p). The dynamic range is better than 73 dB over a bandwidth of 8 kHz.