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Analog Integrator Circuit for Speaker Identification System

IP.com Disclosure Number: IPCOM000092264D
Original Publication Date: 1968-Nov-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 2 page(s) / 44K

Publishing Venue

IBM

Related People

Clapper, GL: AUTHOR

Abstract

In some speaker identification and verification methods time-dependant features are eliminated by summing speaker features over a relatively long interval and comparing the measures so summed against each other. One of the problems encountered is obtaining analog integrators having a sufficiently long time constant. This integrator is suitable for such systems.

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Analog Integrator Circuit for Speaker Identification System

In some speaker identification and verification methods time-dependant features are eliminated by summing speaker features over a relatively long interval and comparing the measures so summed against each other. One of the problems encountered is obtaining analog integrators having a sufficiently long time constant. This integrator is suitable for such systems.

The integrator utilizes three transistors as shown. Transistor X1 is used as a Miller integrator, however, the emitter of X1 is connected to the output providing strong negative feedback which is in addition to the standard feedback via capacitor C from the collector to the base. Transistors X2 and X3 are of opposite conductivity types. Transistor X2 is in a grounded emitter configuration while X3 is an emitter-follower. This combination provides both high current gain and high voltage gain. The direct feedback to the emitter of X1 stabilizes the gain of the whole circuit to a value near unity. Voltage EB at the base of X2 is held within 20 milivolts for the active range EO from -2 to -6 volts. Below -6 volts the clamped diode conducts to hold EO to above -6.3 to -6.4 volts and both X2 and X3 are effectively cut off. A relatively high impedance R to an adjustable voltage +E compensates for leakage in capacitor C. The advantages of the circuit are that the voltage gain is held near unity, voltage offset is low, and all transistors operate efficient...