ALD1108E/ALD1110E

Advanced Linear Devices

2

GENERAL DESCRIPTION

ALD1108E/ALD1110E are monolithic quad/dual EPADs (Electrically

Programmable Analog Device) that utilize CMOS MOSFET with elec-

trically programmable threshold voltage. For a given input voltage,

changing the threshold turn-on voltage of a MOSFET device precisely

changes its drain on-current, resulting in an on-resistance characteris-

tic that can be precisely set and controlled. Used as an in-circuit element

for trimming or setting a combination of voltage and/or current charac-

teristics, it can be programmed via a Personal Computer remotely and

automatically via software control. Once programmed and set, the set

voltage and current levels are stored indefinitely inside the device as a

precisely controlled nonvolatile stored charge, which is not affected

during normal operation of the device, even after power has been turned

off.

The ALD1108E/ALD1110E are devices built with ALD's EPAD technol-

ogy, an electrically programmable device technology refined for analog

applications. The ALD1108E/ALD1110E functions like a regularMOSFET

transistor except with precise user preset threshold voltage. Using the

ALD1108E/ALD1110E is simple and straight forward. The device is

extremely versatile as a circuit element and design component.

It

presents the user with a wealth of possible applications, limited only by

the imagination of the user and the many ways an analog MOSFET

device can be used as a circuit design element. The ALD1108E/

ALD1110E do not need other active circuitry for functionality.

The basic device is a monotonically adjustable device which means the

device can normally be programmed to increase in threshold voltage

and to decrease in drain-on current as a function of a given input bias

voltage. Once adjusted, the voltage and current conditions are perma-

nent and not reversible. However, a given EPAD device can be adjusted

many times to continually increase the threshold voltage. A pair of EPAD

devices can also be connected such that one device is used to adjust a

parameter in one direction and the other device is used to adjust the

same parameter in the other direction.

The ALD1108E/ALD1110E can be pre-programmed with the ALD

EPAD programmer to obtain the desired voltage and current levels. Or,

they can be programmed as an active in-system element in a user

system, via user designed interface circuitry. For more information, see

Application Note AN1108.

APPLICATIONS

inaccessible nodes

and current mirrors

sources

shifter

current bias circuits

circuits

BLOCK DIAGRAM

V- (4)

V+(5)

ALD1110E

EPAD 1

EPAD 2

~

BLOCK DIAGRAM

EPAD 1

EPAD 2

EPAD 3

EPAD 4

V- (5)

V+(13)

ALD1108E

~