JPS57123715A - Transversal type filter - Google Patents

Abstract

PURPOSE:To drive a coefficient at a low speed with wide linear range, by outputting an analog signal by weighting and adding the outputs of devices which output the sum by selecting values of analog memories in accordance with respective stages of digital memories. CONSTITUTION:An analog signal from an input 11 is transferred into an N-stage shift register SR13 by a clock from an input 12. A digital coefficient value 1 or 0 from an input 14 is transferred into the N-stage SR16 by a clock from an input 15. A switch 17 short-circuits only the stages, having 1, of the SR16 to select the values of the corresponding stages of the SR13, and the sum of signals selected by an adder 18 is outputted to a terminal 19. Then, M units of the above-mentioned devices 20 are provided, and the analog signal and clock supplied to inputs 21 and 22 are applied to each device 20 in common to transfer analog signals simultaneously. An analog coefficient value is converted by an A/D converter 23 into a binary code signal, which is applied to the terminal 14 of each device 20 to be transferred simultaneously by a clock from an input 25. Analog signals selected by the respective devices 20 are weighted by resistances and added at a part 27 to output the sum from a terminal 28.