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Browse Prior Art Database

Current Controlled Signal Divider and Photodetector Circuit

IP.com Disclosure Number: IPCOM000077021D
Original Publication Date: 1972-May-01
Included in the Prior Art Database: 2005-Feb-24
Document File: 2 page(s) / 39K

Publishing Venue

IBM

Related People

Chang, DC: AUTHOR

Abstract

The simple circuit of Fig. 1 can be operated as a temperature stable current-controlled signal divider. The sum of adjustable control currents I(1), I(2), flowing thru matched respective diodes D1, D2 is constrained to equal control current I(3). Input signal voltage V(1), within a predefined range of operation, is superimposed either through AC coupling or by resistance coupling of sufficiently high order to have negligible effect on the control currents.

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Current Controlled Signal Divider and Photodetector Circuit

The simple circuit of Fig. 1 can be operated as a temperature stable current- controlled signal divider. The sum of adjustable control currents I(1), I(2), flowing thru matched respective diodes D1, D2 is constrained to equal control current I(3). Input signal voltage V(1), within a predefined range of operation, is superimposed either through AC coupling or by resistance coupling of sufficiently high order to have negligible effect on the control currents.

Incremental resistances R(D1), R(D2) of respective diodes satisfy the relationships:

(Image Omitted)

The magnitude of V(out) therefore is dynamically adjustable by manipulation of the control currents I(1) and/or I(3).

With appropriately matched diodes, the above circuits will operate independent of diode characteristics and temperature variations within defined limits. Another advantage is the relatively constant load presented by the series diode configuration.

If I(1) is changed while I(3) is being held constant, the incremental diode resistances would change compensatingly in opposite directions.

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