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Tapered Transmission Line Circuit Level Shifter

IP.com Disclosure Number: IPCOM000091573D
Original Publication Date: 1968-Mar-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 2 page(s) / 24K

Publishing Venue

IBM

Related People

Burke, RG: AUTHOR

Abstract

Tapered transmission rings can be utilized, in place of the usual circuit converters, to shift the voltage levels of signals being transferred between different circuit types which are at different voltage levels.

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Tapered Transmission Line Circuit Level Shifter

Tapered transmission rings can be utilized, in place of the usual circuit converters, to shift the voltage levels of signals being transferred between different circuit types which are at different voltage levels.

In connection with such lines, the output impedance differs from the input impedance by virtue of the taper. The ratio of the voltages is equal to the square root of the ratio of the impedances. Thus, if the input impedance is 10 ohms and the output impedance is 90 ohms, the output voltage is 3 volts if the input voltage is 1 volt. This is true over a range of frequencies and is analogous to the operation of a very high-pass transformer.

The voltage level A, neglecting some second order effects, is given by A = square root Z2/Z1 -.5V. One DC level must remain intact between the two circuits. This is represented by the -.5V level. A ratio of the impedances of 4 between two types of circuits to be connected might require a line tapering from 25 ohms to 100 ohms. Thus, a transmission line, which is ordinarily required between different circuit types, can be appropriately tapered to give the required shift between the voltage levels. This eliminates the need for special conversion circuits and extra power for level conversion.

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