Browse Prior Art Database

PRECISION TRIANGULAR WAVE GENERATOR

IP.com Disclosure Number: IPCOM000007700D
Original Publication Date: 1996-May-01
Included in the Prior Art Database: 2002-Apr-16
Document File: 3 page(s) / 94K

Publishing Venue

Motorola

Related People

Enrique Ferrer: AUTHOR

Abstract

Triangular wave generator circuits are used in many modem circuit applications. Examples of these are applications in which a pulse width modulator circuit is used, such as in switching power supplies and induction motor control circuits. In this article a circuit is described for generating a quality trian- gular wave, with an amplitude determined by the power supply voltage and a resistor divider network, and at a frequency which is locked to a precision crystal oscillator.

This text was extracted from a PDF file.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 53% of the total text.

Page 1 of 3

MOlVROLA Technical Developments

8

PRECISION TRIANGULAR WAVE GENERATOR

by Enrique Ferrer

  Triangular wave generator circuits are used in many modem circuit applications. Examples of these are applications in which a pulse width modulator circuit is used, such as in switching power supplies and induction motor control circuits. In this article a circuit is described for generating a quality trian- gular wave, with an amplitude determined by the power supply voltage and a resistor divider network, and at a frequency which is locked to a precision crystal oscillator.

  Shown in Figure 1 is the circuit schematic. Waveforms at various nodes in the circuit are shown in Figure 2.

  The operation of the circuit is as follows: The amplitude ofthe triangular wave is set by the supply voltage and by the resistor divider network RI, R2, and R3. The triangular wave output is generated at the pin labeled OUT The OPAMP transistor N3 and resistor R form a voltage to current converter. The current developed at the output of the voltage to current converter (current 13), is mirrored via tran- sistors Pl and P2 to one side of the analog gate Tl (current II). Current 13 is also mirrored via transis-

tors Pl, P3, NI and N2 to one side of the analog gate T2 (current 12). When TI is "on" current II charges capacitor C starting the rising edge ofthe triangular wave. When the voltage at capacitor C is greater than the voltage VA at the positive input of compa- rator COMPl, the output of compar...