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Digitally Controlled Analog Output Device

IP.com Disclosure Number: IPCOM000093894D
Original Publication Date: 1966-Mar-01
Included in the Prior Art Database: 2005-Mar-06
Document File: 2 page(s) / 27K

Publishing Venue

IBM

Related People

Styczinski, DA: AUTHOR

Abstract

The output E0 is equal to the analog input Ein plus an increment proportional to the product of the analog and digital inputs. The analog input voltage is applied to one input of operational amplifier 10 having a feedback resistance Rf to its other input. Output E0 = Ein (1 + Rf/ Rin) = Ein (1 + sigma YI/YF) where Rin is the parallel combination of all the input resistors that are grounded via the associated transistor. YF = 1/Rf and sigma Y1 is the sum of the admittances of the grounded input resistors. Resistors R1, R2, R4, R8 and R16 are binary-weighted. The resistors are either floating or are at ground potential depending upon whether or not the associated transistor is off or is conducting respectively. This circuit has high input impedance.

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Digitally Controlled Analog Output Device

The output E0 is equal to the analog input Ein plus an increment proportional to the product of the analog and digital inputs. The analog input voltage is applied to one input of operational amplifier 10 having a feedback resistance Rf to its other input. Output E0 = Ein (1 + Rf/ Rin) = Ein (1 + sigma YI/YF) where Rin is the parallel combination of all the input resistors that are grounded via the associated transistor. YF = 1/Rf and sigma Y1 is the sum of the admittances of the grounded input resistors. Resistors R1, R2, R4, R8 and R16 are binary- weighted. The resistors are either floating or are at ground potential depending upon whether or not the associated transistor is off or is conducting respectively. This circuit has high input impedance.

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