One-chip IIL-analog multifrequency oscillator for pushbutton dialer

To realize a low-cost and highly reliable pushbutton dialer, a DMFO (digital multifrequency oscillator) LSI has been developed. DMFO is a one-chip monolithic LSI in an IIL-analog combination employing the frequency synthesis principle. This synthesizer method has been adopted to satisfy such requirements as very long term stability and the elimination of precision discrete components and the frequency adjustment process. It is also necessary to satisfy requirements for wide temperature range, wide supply current range, and total out-of-band power in end-to-end use. This DMFO LSI meets these requirements with new circuit configurations and by combining many functions on the same chip, while simultaneously lowering the cost of the dialer by using an IIL-analog LSI technology without complex additional processes. As a result, an approximately 500-gate IIL and approximately 200-element analog circuit have been integrated into a 3.43×3.95 mm chip.