GENERAL DESCRIPTION

The ALD212900A/ALD212900 precision N-Channel EPAD® MOSFET array is

precision matched at the factory using ALD’s proven EPAD® CMOS technology.

These dual monolithic devices are enhanced additions to the ALD110900A/

ALD110900 EPAD® MOSFET Family, with increased forward transconductance

and output conductance, particularly at very low supply voltages.

Intended for low voltage, low power small signal applications, the ALD212900A/

ALD212900 features Zero-Threshold™ voltage, which enables circuit designs

with input/output signals referenced to GND at enhanced operating voltage

ranges. With these devices, a circuit with multiple cascading stages can be

built to operate at extremely low supply/bias voltage levels. For example, a

nanopower input amplifier stage operating at less than 0.2V supply voltage has

been successfully built with these devices.

ALD212900A EPAD MOSFETs feature exceptional matched pair device electrical

characteristics of Gate Threshold Voltage VGS(th) set precisely at 0.00V

+0.01V, IDS = +20μA @ VDS = 0.1V, with a typical offset voltage of only +0.001V

(1mV). Built on a single monolithic chip, they also exhibit excellent temperature

tracking characteristics. These precision devices are versatile as design components

for a broad range of analog small signal applications such as basic

building blocks for current mirrors, matching circuits, current sources, differential

amplifier input stages, transmission gates, and multiplexers. They also excel

in limited operating voltage applications, such as very low level voltageclamps

and nano-power normally-on circuits.

In addition to precision matched-pair electrical characteristics, each individual

EPAD MOSFET also exhibits well controlled manufacturing characteristics, enabling

the user to depend on tight design limits from different production batches.

These devices are built for minimum offset voltage and differential thermal response,

and they can be used for switching and amplifying applications in +0.1V

to +10V (+0.05V to +5V) powered systems where low input bias current, low

input capacitance, and fast switching speed are desired. At VGS > 0.00V, the

device exhibits enhancement mode characteristics whereas at VGS < 0.00V the

device operates in the subthreshold voltage region and exhibits conventional

depletion mode characteristics, with well controlled turn-off and sub-threshold

levels that operate the same as standard enhancement mode MOSFETs.

The ALD212900A/ALD212900 features high input impedance (2.5 x 1010Ω) and

high DC current gain (>108). A sample calculation of the DC current gain at a

drain output current of 30mA and input current of 300pA at 25°C is 30mA/300pA

= 100,000,000, which translates into a dynamic operating current range of about

eight orders of magnitude. A series of four graphs titled “Forward Transfer Characteristics”,

with the 2nd and 3rd sub-titled “expanded (subthreshold)” and “further

expanded (subthreshold)”, and the 4th sub-titled “low voltage”, illustrates

the wide dynamic operating range of these devices.

Generally it is recommended that the V+ pin be connected to the most positive

voltage and the V- and IC (internally-connected) pins to the most negative voltage

in the system. All other pins must have voltages within these voltage limits

at all times. Standard ESD protection facilities and handling procedures for static

sensitive devices are highly recommended when using these devices.

FEATURES & BENEFITS

• Zero Threshold™ VGS(th) = 0.00V +0.01V

• VOS (VGS(th) match) to 2mV/10mV max.

• Sub-threshold voltage ( nano-power) operation

• < 100mV min. operating voltage

• < 1nA min. operating current

• < 1nW min. operating power

• > 100,000,000:1 operating current ranges

• High transconductance and output conductance

• Low RDS(ON) of 14Ω

• Output current >50mA

• Matched and tracked tempco

• Tight lot-to-lot parametric control

• Positive, zero, and negative VGS(th) tempco

• Low input capacitance and leakage currents

APPLICATIONS

• Low overhead current mirrors and current sources

• Zero Power Normally-On circuits

• Energy harvesting circuits

• Very low voltage analog and digital circuits

• Zero power fail-safe circuits

• Backup battery circuits & power failure detector

• Extremely low level voltage-clamps

• Extremely low level zero-crossing detector

• Matched source followers and buffers

• Precision current mirrors and current sources

• Matched capacitive probes and sensor interfaces

• Charge detectors and charge integrators

• High gain differential amplifier input stage

• Matched peak-detectors and level-shifters

• Multiple Channel Sample-and-Hold switches

• Precision Current multipliers

• Discrete matched analog switches/multiplexers

• Nanopower discrete voltage comparators