Browse Prior Art Database

Sine Wave Generator

IP.com Disclosure Number: IPCOM000104117D
Original Publication Date: 1993-Mar-01
Included in the Prior Art Database: 2005-Mar-18
Document File: 4 page(s) / 48K

Publishing Venue

IBM

Related People

Bailey, JA: AUTHOR [+2]

Abstract

A simple way of generating accurate sinusoidal signals is presented. The proposed sine wave generator is implemented with a resistive divider, a set of switches operated sequentially by control signals derived digitally from a system clock and a low pass filter.

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Sine Wave Generator

      A simple way of generating accurate sinusoidal signals is
presented.  The proposed sine wave generator is implemented with a
resistive divider, a set of switches operated sequentially by control
signals derived digitally from a system clock and a low pass filter.

      The circuit is shown in Fig. 1.  A resistive divider comprising
R sub 1 through R sub N+1 define voltage levels V sub 1 through V sub
N.  The weight of the resistors is chosen so that voltages V sub 1
through V sub N correspond to N sampled values of a sine wave at
times nT sub s, where n is an integer from 1 to N and T sub s is the
sampling interval.  Node V sub s is connected to each V sub i via a
simple switch S sub i.  Thus, if the switches are operated by a set
of control signals with sequential phases as shown in Fig. 2, node V
sub s develops a voltage:

(1)          V sub s(t) =  Sum A here <(2&pi.n T sub s
        over T sub 0)>h(t - nT sub s)

      A is determined by the voltage source and the resistor string;
T sub 0 is the desired sine period.

      The signal described by (1) is recognized as a sine wave of fre
quency 1/T sub 0 sampled with the flat top sampler h(t) shown in Fig.
3 at a rate 1/T sub s.  Thus, V sub s(t) can be reconstructed into a
smooth sinusoidal by filtering it with a low pass with a cutoff
frequency slightly higher that 1/T sub 0.  One may define:

(2)                           N = 1 +...