Kiyoshi Fukahori - San Jose CA
Yukio Nishikawa - San Jose CA
Precision Monolithics, Inc. - Santa Clara CA
An I. C. integrator circuit is provided with an active tuneable element by which a precise integrator time constant can be established, despite variations in the values of individual circuit components. A plurality of integrator circuits are connected in an overall frequency responsive circuit, each integrator circuit having a input transconductance stage, an output integrating stage, and an adjustable intermediate conditioning stage, the latter stage preferably comprising a Gilbert multiplier circuit. The time constant of each integrator circuit is controlled by the conditioning stage, which in turn is under the control of a bias circuit common to all of the integrator circuits. A desired net frequency response characteristic can be achieved by simple adjustments to the common bias circuit, despite normal tolerances and variations among individual integrator circuits.
The circuit is completely integrated, is capable of operating at audio as well as at higher frequency ranges, has a greater tuneable range than prior art devices, and is highly linear.