Many companies try to develop MEMS switch technology, be faced with mass production likewise nevertheless and the challenge that large quantities of quantities offer reliable product. Among them ADI company throws MEMS switch item actively, built oneself advanced MEMS switch makes installation, in order to satisfy the requirement that industry produces to the quantity.

 

Fundamental

 

The Liang Kai of small treatment cantilever that the key of technology of ADI MEMS switch is electrostatic drive involves package concept. Can inspect it the mechanical switch of micron measure substantially, its metal adopts electrostatic drive to metallic contact.

 

Switch uses 3 terminal configuration to have link. Source pole, grid and leakage can regard these terminal as on the function extremely. Issue the graph is switch to simplify sketch map, circumstance A states switch is in off position.

 

 

Bring to bear on a volts d.c. at grid, one can arise on switch bridge electrostatic next pulling force. Of this kind of static electric power and smooth andante capacitance losing electrified board the appeal between is identical. When grid voltage inclined rise to enough when high cost, its meeting generation is enough big attraction (gules arrowhead) the bedspring obstruction that will overcome switch bridge, switch bridge begins to be down shift, till contact contacts leakage pole. Place of following attempt condition B notify the procedure.

 

 

At this moment, source pole is mixed the circuit between leakage pole closes, switch puts through. The bedspring constant of the real power volume that pulls down switch bridge place to need and cantilever bridge reachs his to be concerned to athletic obstruction. Attention: Although be in,put through the position, switch bridge still has on the bedspring strength that draws switch (blue arrowhead) , but want next pulling only electrostatic force (gules arrowhead) bigger, switch can maintain put through condition.

 

Finally, should move when dividing grid voltage (C of circumstance laying a plan) , when 0V is on grid electrode namely, electrostatic appeal disappears, switch bridge is had as bedspring enough big refreshment force (blue arrowhead) will disconnect source pole is mixed the join between leakage pole, return next primitive close the position.

 

 

Next graphs 1 to use single-broadsword event 4 cast (ST4T) multichannel answer with implement the enlarge graph of the 4 MEMS switch of configuration. Every switch bridge has contact of sex of 5 shunt-wound block, the resistor when in order to reduces switch to close raises power to handle ability.

 

Graph 1, bridge of switch of formula of 4 MEMS cantilever (SP4T is configured)

 

Driving voltage of tall dc of MEMS switch need comes with switch of electrostatic force drive. To make parts of an apparatus is used easily as far as possible and guarantee performance further, ADI company designed integrated circuit of driver of form a complete set (IC) will produce tall volts d.c. , its and MEMS switch are enclosed in QFN norms dimension jointly. In addition, the tall driving voltage that produces brings to bear on with controlled means the grid electrode at switch. It with time of small second class inclined rise supreme tension. Inclined litre of attraction that conduces to control switch bridge and next pulling, improve the behavioral function of switch, dependability and service life. Pursue below the 2 driver IC in showing a QFN is enclosed and MEMS chip example. Driver IC needs power supply of a low voltage, small electric current only, but as logistic as standard CMOS driving voltage is compatible. This kind of driver that encloses together makes switch very easy use, and its power comsumption asks very low, arrive in 10mW about inside 20mW limits.

 

Graph 2, driver IC (left) with MEMS switch chip (right) install and line solder is on metallic down-lead frame

 

Performance dominant position

 

With ADGM1004/ADGM1304 SP4T the department is labelled exemple, its each parameter and traditional Electromechanical relay are compared (graph 3) Having many clear advantages.

 

Graph 3, ADGM1004/ ADGM1304 MEMS and traditional Electromechanical relay are compared

 

ADGM1004/ADGM1304 SP4T contains integrated type driver with , apply to relay substitute, RF checks an instrument, and RF switch. Product standards detail and relevant evaluate board EVAL-ADGM1004EBZ can scan Digi-Key product only page.

 

Use give a demonstration

 

In the past, want to check function of switch of Dc/RF of the implementation in equipment in ATE, must use EMR switch. But, because be put in the following problem, use relay may restrict systematic performance:

 

Relay the size of switch is larger, must abide by ” of “ forbidden zone to design regulation, this means it to want to take up very large area, lack checks but expansibility.

 

Relay the service life of switch is finite, it is millions only periodic.

 

Must cascade many relay, the switch that just can realize need is configured (for example, SP4T configuration needs 3 SPDT relay) .

 

When use relay, the likelihood encounters PCB to assemble a problem, cause rate of very high PCB do poorly done work over again normally.

 

As a result of wiring limitation and relay function is restricted, it is very difficult to achieve complete bandwidth performance.

 

Relay drive speed is slow, the time that is millisecond class measures level, limitted test rate thereby.

 

Give 16:1 with typical Dc/RF switch fanMultichannel answer is with the function exemple (graph 4) , relay of need nine DPDT EMR and a relay driver IC, will realize 18:1Multichannel answer uses a function (8 DPDT relay can produce 14:1 onlyMultichannel answer uses a function) . Graph 5 in, showed identical fan gives switch function, use 5 ADGM1304 or ADGM1004SP4T MEMS switch only, be able to simplify consequently.

 

 

Graph 6 in the picture that showed the vision that implements plan of these two principles demonstrates PCB. Left showed physical relay solution, showed relay the solution took up how old area, maintain the semmetry between wiring join how difficult, and the demand to driver IC. From on the right side of can see, take up PCB area is reduced, the wiring complexity of switch function is reduced. Press area computation, MEMS switch makes take up the area reduces 68% above, press volumenometer to calculate, reduce 95% above possibly.

 

Low voltage of the buy inside ADGM1304 and ADGM1004 MEMS switch, can become independent pilot switch driver; Accordingly, they do not need exterior drive IC. The height that encloses as a result of MEMS switch is lesser (of ADGM1304 enclose height to be 0.95mm, of ADGM1004 enclose height to be 1.45mm) , because this switch can install the opposite of PCB. Enclosed height lesserly to increase realizable channel density.

 

Graph 6. DC/RF fan gives the vision of test board to compare: Realize 16:1Multichannel answer uses a function, switch of use nine EMR (Zun Huang) with 5 MEMS switch (right red)

 

Article brief summary

 

Finally, small size solution normally to any markets it is a crucial requirement. MEMS has the advantage of be convinced making a person in this respect. Next graphs 7 compared the ADI SP4T after enclosing with objective photograph (four switch) MEMS switch design and typical DPDT (four switch) the dimension of Electromechanical relay. MEMS switch saved a large number of spaces, 5% what its bulk is equivalent to relay only. This kind exceeds small size to be being shown saved PCB board area, raise the possibility of the double-faced development of PCB board. The manufacturer of automatic test equipment that this one advantage increases channel density to urgent need is particularly valuable.

 

Graph 7, class of chip of ADI down-lead casing encloses MEMS switch (four switch) with relay of RF of typical Electromechanical type (four switch) dimension is compared