acquisitionZONE Products for the week of June 20, 2005
Advanced Linear Devices Inc (ALD), a design innovation leader in analog semiconductors, today announces an industry breakthrough zero threshold MOSFET device introducing a new level of precision in analog design that makes 0.1-Volt circuits possible for the first time.
The Quad/Dual N-Channel Matched Pair Zero Threshold MOSFETs are matched at the factory using ALD's exclusive EPAD CMOS technology to achieve the industry's lowest threshold voltage of 0.0V with an exceptional range of variation from 0.01V to -0.01V and an offset voltage of just 2 mV. These MOSFETS advance the state-of-the-art in small signal transistors with a level of precision that opens the door to micropower technology never before achievable. Basic amplifier applications, for example, operating at supply voltages of only 0.20V and power dissipation of less than 1 microwatt are where zero threshold MOSFETs will revolutionize current day analog circuit design.
With this new analog component, the shackle of "threshold turn-on voltage" placed on the circuit design engineer has just been broken. The operating voltage of a circuit will no longer be limited by the gate threshold voltage or the bipolar turn-on voltage. Now a simple circuit using this new device can be constructed to operate on as little as a 20 mV supply. On more complicated circuits, consisting of many stages stacked on top of each other, a system operating voltage of just 0.2V to 0.45V becomes a reality.
Providing zero threshold MOSFETs for the first time will support the design of analog circuits that operate on less than one microwatt, giving designers the flexibility to extend the maximum signal range of low voltage systems. Such versatility supports the operation of countless applications from ultra-sensitive, remote sensor arrays to implantable medical devices. This new device can be classified as both an enhancement mode device when operated above the threshold voltage and a depletion mode MOSFET device when operated at or below threshold voltage.
Ultra-Low Power Zero Threshold MOSFETS with EPAD technology, also serve as an excellent replacement for normally closed relay applications since they are always in the "on" state without power. For amplifier and sensor circuits, they enable long-term power conservation. This offers the industry the ability to design circuits with operating power up to 100 times lower than competitive MOSFETs. In terms of matched threshold voltages, ALD EPAD MOSFETs are vastly more accurate than currently available devices. In addition, a zero threshold MOSFET greatly expands useful operating signal range, enabling rail-to-rail circuit operation for very low voltage analog circuits.
"In designing the Zero Threshold MOSFET, ALD wanted to eliminate
some of the design limitations that analog circuit designers deal with every
day," said Robert Chao, President and CEO of ALD. "ALD is now
offering that possibility with Zero Threshold EPAD MOSFETs devices which
enable the operation of delicate sensors from extremely remote locations
for sensitive and critical security applications. Even implantable medical
devices that must perform in-situ for many years can now be developed to
promote longer operational life to avoid invasive surgery for the replacement
of these devices. The world is demanding lower voltage operation from a
variety of electronic devices and these highly precise MOSFET devices will
close the gap towards achieving this goal."
analogZONE Says . . .
I have absolutely no idea how Advanced Linear Devices is performing this little trimming miracle but I am very glad that I'm not in the middle of writing a textbook about FET device operation! It is strange to have devices that are both enhancement- and depletion-mode at the same time.
Two grades of device are being made available. The standard has a zero gate threshold voltage with a tolerance of ±20 mV and a maximum offset of 10 mV; an "A" suffix tightens the gate threshold "zero" to ±10 mV with a 2 mV maximum offset. The ALD11080 is a quad array of MOSFETs with a common source on one pair and a common source on the second pair. The ALD11090 is a dual array sharing the same architecture. I'm sure one of the early things ALD will be asked is for an array with a common drain instead of source.
With well-sub-1 V amplifiers possible with this technology, with guaranteed rail-to-rail, some of our thinking will have to change. I'm not at all sure what those thoughts should be at this stage. There are two curves with the preliminary two page data sheet: one of the most important specifications - noise - is not quoted, nor do we have any ac characteristics to look at. Whatever those numbers are will determine whether we have an amplifier breakthrough on our hands or whether we are looking at devices that will only be of use for non-signal paths. With VGS at +4V VDS at +5 V the devices are only producing 3.0 mA drain current.
Regardless of the signal-path usability of these devices, however, they are a major breakthrough in the way that other circuits can be put together. They will certainly change the way that current mirrors and multipliers will be put together, as well as comparators, zero crossing detectors and switches. The tempco of the MOSFETs in each array will be extremely well matched and that also suggests differential circuits with high input performance.
The parts are available in PDIP-16 and SOIC-16 for the quads and PDIP-8 and SOIC-8 for the duals. Pricing starts at $0.91 for 1000-piece lots.