ADGM1004JCPZ-R2 Datasheet ADGM1004JCPZ-R2, ADGM1004JCPZ-RL7 | P16-P18

Data Sheet ADGM1004

Rev. A | Page 15 of 20

INTERNAL OSCILLATOR/EXTD_EN

The ADGM1004 has an internal oscillator running at a nominal

11.5 MHz. This oscillator drives the charge pump circuitry that

provides the actuation voltage for each of the switch gate elec-

trodes. Although this oscillator is very low power, the 11.5 MHz

signal is coupled to the switch and can be considered a noise

spur on the switch channels. The magnitude of this feedthrough

noise spur is specified in Table 1 and is typically −115 dBm when

one switch is on. When all four switches are simultaneously on,

the feedthrough goes up to −94 dBm. V

level and temperature

changes affect the frequency of the noise spur. For the maximum

and minimum frequency range over temperature and voltage

supply range, see Table 1.

Setting the EXTD_EN pin high disables the internal oscillator

and driver boost circuitry. With the driver boost circuitry

disabled, applying an external 80 V dc to the V

pin enables the

switch to be driven via the digital interface, as outlined in Table 4.

Disabling the boost circuitry and driving it with an external

80 V dc source completely eliminates oscillator feedthrough that

can be an issue in some applications.

TYPICAL OPERATING CIRCUIT

Figure 28 shows the typical operating circuit for the ADGM1004

as used in the EVA L -ADGM1004EBZ evaluation board. A 47 pF

external capacitor is required on the V

pin; this capacitor is a

holding capacitor for the 80 V dc gate drive voltage. Because the

device incorporates the boost circuitry required to generate the

80 V dc, the boost circuitry results in an overall saving in the

number of external components required, and therefore reduces

board space needed to use the device.

In the circuit shown in Figure 28, V

is connected to 3.3 V. EP1

connects to EP2 internally. Typically, one large GND pad on the

PCB is used to short together EP1 and EP2. Figure 28 shows the

ADGM1004 configured to use the internal oscillator as the

reference clock to the driver IC control circuit. Alternatively, set

Pin 7 high and apply 80 V dc directly to Pin 24 to disable the

internal oscillator and eliminate all oscillator feedthrough. The

switches can then be controlled as normal via the logic control

interface, Pin 1 to Pin 4.

GND

RFC

GND

EXTD_EN

GND

RF3

RF2

GND

RF1

23 22 21 20 19 18

8 9

10 11 12

IN1

IN2

IN3

IN4

GND

RF4

GND

IN1

IN2

IN3

IN4

47pF

0.1µF

3.3V

RFOUT

RF2 IN

RF1 IN

RF4 IN

RF3 IN

EP1 EP2

TOP VIEW

15173-023

Figure 28. Typical Operating Circuit

ADGM1004 Data Sheet

Rev. A | Page 16 of 20

APPLICATIONS INFORMATION

FLOATING NODE AVOIDANCE

As outlined in the Theory of Operation section, to actuate the

switch, 80 V dc is generated internally in the ADGM1004 device

and applied to a gate electrode, which creates the electrostatic

attraction force that actuates the switch. Without an external

impedance to a dc voltage reference, charges can increase on the

switch terminals, causing voltages to float to unknown levels,

which can lead to unreliable actuation behavior with potential

to damage the switch. To ensure correct and reliable switch

actuation, ensure that all switch nodes have a dc voltage

reference such as a connection to another active component

with an internal voltage reference or an impedance to ground.

Figure 29 to Figure 32 show examples of four cases to avoid

where floating nodes can occur when using the switch. These

include the following:

• RFx pins must not be open circuit

• A series capacitor connected directly to the switch can

result in a floating node condition

• Connecting the RFx pin of two switches directly together

or RFC to RFx can result in a floating node condition

RFx RFC

FLOATING

OPEN CIRCUIT

15173-024

Figure 29. RFx Left Open Circuit

RFx RFC

FLOATING

15173-025

Figure 30. Series Capacitor Connected Directly to the Switch Can Result in a

Floating Node Condition

RFx

RFC

FLOATING

RFx

RFC

15173-026

Figure 31. Connecting the RFx Pin of Two Switches Directly Together Can

Result in a Floating Node Condition

RFx

RFC

FLOATING

RFC

RFx

15173-027

Figure 32. Connecting RFC to RFx Can Result in a Floating Node Condition

Providing a dc voltage reference to the switch ensures a correct

gate to beam voltage differential to drive the switch and prevents

unreliable actuation. In a typical application, a 50 Ω termination

connected to the switch provides a constant dc voltage reference.

Most amplifiers and other active devices also have an internal

dc voltage reference; therefore, when they are connected

directly to the switch, they provide a dc voltage reference and

avoid any floating node issues. If there is no inherent dc voltage

reference in the application circuit, a 10 MΩ shunt resistor or

inductor on the source (RFx) pin of the MEMS switch must be

added to provide a voltage reference. The addition of external

shunt resistors increases the leakage above the specification

listed in Table 1. Figure 33 shows this type of voltage reference

configuration.

RFx

RFC

15173-028

Figure 33. Switch Configuration Providing a Voltage Reference

Figure 34 and Figure 35 illustrate typical cascaded switch use

cases and the corresponding schemes to mitigate floating node

risks. The path between the two switches needs a voltage reference

to ground; otherwise, the path can float to an unknown voltage

and subsequently cause unreliable actuations, possibly leading

to hot switching events or switches remaining in the on state.

Use 10 MΩ shunt resistors to provide the voltage references.

RFC

RF1

RF2

RF3

RF4

RF1

RF2

RF3

RF4

RFC

15173-029

Figure 34. Two ADGM1004 Devices Connected Together with Shunt Resistors

to Mitigate Floating Nodes

RFC

RF1

RF2

RF3

RF4

RFC

RF1

RF2

RF3

RF4

RFC

RF1

RF2

RF3

RF4

15173-030

Figure 35. Three ADGM1004 Devices Connected Together with Shunt

Resistors to Mitigate Floating Nodes

Data Sheet ADGM1004

Rev. A | Page 17 of 20

CONTINUOUSLY ON LIFETIME

If the switch channel is in the on state for extended periods of

time (more than seven years), the switch can fail to turn off due

to mechanical degradation effects. The continuously on lifetime

feature is duty cycle dependent; in low duty cycle uses cases (for

example, 10% on, 90% off), there is no lifetime degradation.

The ADGM1004 has a continuous on lifetime specification of

7.2 years (typical) at 50°C; see Table 1.

Figure 36 shows the extrapolated failure time of 31 switches where

all of them were held in the on state continuously at 50°C until they

failed to open. The lifetime is affected by temperature. As the

temperature increases above 50°C, the continuously on lifetime

degrades significantly. However, for lower temperatures, the

lifetime improves.

UNRELIABILITY (% OF POPULATION)

10 100 1,000

CONTINUOUSLY ON TIME (DAYS)

10,000 100,000

15173-031

= 3.3V

Figure 36. Continuously On Lifetime, V

= 3.3 V, 50°C, Sample Size = 31 Devices

P1-P3 P4-P6 P7-P9 P10-P12 P13-P15 P16-P18 P19-P21

ADGM1004JCPZ-R2

Mfr. #:

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Manufacturer:

Analog Devices Inc.

Description:

RF Switch ICs >1kV HBM ESD MEMS Switch Solution

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