Datasheet AD825 Datasheet (Analog Devices)

Low Cost, General-Purpose

–

FEATURES

High speed

41 MHz, −3 dB bandwidth 125 V/µs slew rate

80 ns settling time Input bias current of 20 pA and noise current of 10 fA/√Hz Input voltage noise of 12 nV/√Hz Fully specified power supplies: ±5 V to ±15 V Low distortion: −76 dB at 1 MHz High output drive capability

Drives unlimited capacitance load

50 mA min output current No phase reversal when input is at rail Available in 8-lead SOIC

APPLICATIONS

CCDs Low distortion filters Mixed gain stages Audio amplifiers Photo detector interfaces ADC input buffers DAC output buffers

High Speed JFET Amplifier

AD825

CONNECTION DIAGRAMS

NC

1

AD825

–IN

2

TOP VIEW

3

+IN

(Not to Scale)

V

4

S

NC = NO CONNECT

Figure 1. 8-Lead Plastic SOIC (R) Package

1

NC NC

2

NC

3

–INPUT +INPUT

–V

AD825

4

TOP VIEW

5

(Not to Scale)

6

S

7

NC

8

NC

NC = NO CONNECT

Figure 2. 16-Lead Plastic SOIC (R-16) Package

NC

8

+V

7

S

6

OUTPUT NC

5

00876-E-001

16

NC NC

15

NC

14

+V

13

S

OUTPUT

12 11

NC

10

NC

9

NC

00876-E-002

GENERAL DESCRIPTION

The AD825 is a superbly optimized operational amplifier for high speed, low cost, and dc parameters, making it ideally suited for a broad range of signal conditioning and data acquisition applications. The ac performance, gain, bandwidth, slew rate, and drive capability are all very stable over temperature. The AD825 also maintains stable gain under varying load conditions.

The unique input stage has ultralow input bias current and input current noise. Signals that go to either rail on this high performance input do not cause phase reversals at the output. These features make the AD825 a good choice as a buffer for MUX outputs, creating minimal offset and gain errors.

The AD825 is fully specified for operation with dual ±5 V and ±15 V supplies. This power supply flexibility, and the low supply current of 6.5 mA with excellent ac characteristics under all supply conditions, makes the AD825 well-suited for many demanding applications.

Rev. F

Information furnished by Analog Devices is believed to be accurate and reliable. However, no responsibility is assumed by Analog Devices for its use, nor for any infringements of patents or other rights of third parties that may result from its use. Specifications subject to change without notice. No license is granted by implication or otherwise under any patent or patent rights of Analog Devices. Trademarks and registered trademarks are the property of their respective owners.

10V 200ns

10V

Figure 3. Performance with Rail-to-Rail Input Signals

www.analog.com

00876-E-003

AD825

SPECIFICATIONS

All limits are determined to be at least four standard deviations away from mean value. At TA = 25°C, VS = ±15 V, unless otherwise noted.

Table 1.

AD825A Parameter Conditions VS Min Typ Max Unit

DYNAMIC PERFORMANCE

Unity Gain Bandwidth ±15 V 23 26 MHz

Bandwidth for 0.1 dB Flatness Gain = +1 ±15 V 18 21 MHz

−3 dB Bandwidth Gain = +1 ±15 V 44 46 MHz

Slew Rate R

Settling Time to 0.1% 0 V to 10 V Step, AV = −1 ±15 V 150 180 ns

to 0.1% 0 V to 10 V Step, AV = −1 ±15 V 180 220 ns Total Harmonic Distortion FC = 1 MHz, G = −1 ±15 V −77 dB Differential Gain Error NTSC ±15 V 1.3 %

(R

= 150 Ω) Gain = +2

LOAD

Differential Phase Error NTSC ±15 V 2.1 Degrees

(R

= 150 Ω) Gain = +2

LOAD

INPUT OFFSET VOLTAGE ±15 V 1 2 mV T

Offset Drift 10 µV/°C

INPUT BIAS CURRENT ±15 V 15 40 pA T T INPUT OFFSET CURRENT ±15 V 20 30 pA T T OPEN-LOOP GAIN V R V R V R COMMON-MODE REJECTION VCM = ±10 ±15 V 71 80 dB INPUT VOLTAGE NOISE f = 10 kHz ±15 V 12

INPUT CURRENT NOISE f = 10 kHz ±15 V 10 INPUT COMMON-MODE VOLTAGE RANGE ±15 V ±13.5 V OUTPUT VOLTAGE SWING R

R

Output Current ±15 V 50 mA Short-Circuit Current ±15 V 100 mA

INPUT RESISTANCE 5 ×1011 Ω INPUT CAPACITANCE 6 pF OUTPUT RESISTANCE Open Loop 8 Ω POWER SUPPLY

Quiescent Current ±15 V 6.5 7.2 mA

T

= 1 kΩ, G = +1 ±15 V 125 140 V/µs

LOAD

to T

MIN

MAX

MIN

MAX

5 pA

MIN

MAX

= ±10 V ±15 V

OUT

= 1 kΩ 70 76 dB

LOAD

= ±7.5 V ±15 V

OUT

= 1 kΩ 70 76 dB

LOAD

= ±7.5 V ±15 V

OUT

= 150 kΩ (50 mA Output) 68 74 dB

LOAD

= 1 kΩ ±15 V 13 ±13.3 V

LOAD

= 500 Ω ±15 V 12.9 ±13.2 V

LOAD

to T

MIN

±15 V 7.5 mA

MAX

5 mV

5 pA 700 pA

440 pA

nV/√ fA/√

Hz

Rev. F | Page 3 of 12

AD825

All limits are determined to be at least four standard deviations away from mean value. At TA = 25°C, VS = ±5 V unless otherwise noted.

Table 2.

AD825A Parameter Conditions VS Min Typ Max Unit

DYNAMIC PERFORMANCE

Unity Gain Bandwidth ±5 V 18 21 MHz Bandwidth for 0.1 dB Flatness Gain = +1 ±5 V 8 10 MHz

−3 dB Bandwidth Gain = +1 ±5 V 34 37 MHz Slew Rate R Settling Time to 0.1% −2.5 V to +2.5 V ±5 V 75 90 ns

to 0.01% −2.5 V to +2.5 V ±5 V 90 110 ns Total Harmonic Distortion FC = 1 MHz, G = −1 ±5 V −76 dB Differential Gain Error NTSC ±5 V 1.2 %

(R

= 150 Ω) Gain = +2

LOAD

Differential Phase Error NTSC ±5 V 1.4 Degrees

(R

= 150 Ω) Gain = +2

LOAD

INPUT OFFSET VOLTAGE ±5 V 1 2 mV T

Offset Drift 10 µV/°C

INPUT BIAS CURRENT ±5 V 10 30 pA T T INPUT OFFSET CURRENT ±5 V 15 25 pA T

Offset Current Drift T

OPEN-LOOP GAIN V R R COMMON-MODE REJECTION VCM = ±2 V ±5 V 69 80 dB INPUT VOLTAGE NOISE f = 10 kHz ±5 V 12

INPUT CURRENT NOISE f = 10 kHz ±5 V 10 INPUT COMMON-MODE VOLTAGE RANGE ±5 V ± 3.5 V

OUTPUT VOLTAGE SWING R R

Output Current ±5 V 50 mA Short-Circuit Current 80 mA

INPUT RESISTANCE 5 ×1011 Ω INPUT CAPACITANCE 6 pF OUTPUT RESISTANCE Open Loop 8 Ω POWER SUPPLY

Quiescent Current ±5 V 6.2 6.8 mA

T POWER SUPPLY REJECTION VS = ±5 V to ±15 V 76 88 dB

= 1 kΩ, G = −1 ±5 V 115 130 V/µs

LOAD

to T

MIN

MAX

5 pA

MIN

MAX

MIN

MAX

= ±2.5 ±5 V

OUT

= 500 Ω 64 66 dB

LOAD

= 150 Ω 64 66 dB

LOAD

= 500 Ω +3.2 ±3.4 V

LOAD

= 150 Ω ±5 V +3.1 ±3.2 V

LOAD

to T

MIN

MAX

5 mV

600 pA

5 pA 280 pA

±5 V 7.5 mA

nV/√ fA/√

Hz

Rev. F | Page 4 of 12

AD825

–

ABSOLUTE MAXIMUM RATINGS

Table 3.

Parameter Rating

Supply Voltage ±18 V Internal Power Dissipation

1

Small Outline (R) See Figure 6 Input Voltage (Common Mode) ±V Differential Input Voltage ±V

S

Output Short-Circuit Duration See Figure 6 Storage Temperature Range (R, R-16) −65°C to +125°C Operating Temperature Range −40°C to +85°C Lead Temperature Range

300°C

(Soldering 10 sec)

Stresses above those listed under Absolute Maximum Ratings may cause permanent damage to the device. This is a stress rating only; functional operation of the device at these or any other conditions above those indicated in the operational section of this specification is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability.

1

Specification is for device in free air:

8-lead SOIC package: θ

16-lead SOIC package: θ

= 155°C/W

JA

= 85°C/W

JA

2.5

2.0

1.5

PIN CONFIGURATIONS

NC

1

–IN +IN

AD825

2

TOP VIEW

3

(Not to Scale)

V

4

S

NC = NO CONNECT

Figure 4. 8-Lead SOIC

1

NC NC

2

NC

3

–INPUT

4

+INPUT

5

(Not to Scale)

6

–V

S

7

NC

8

NC

NC = NO CONNECT

Figure 5. 16-Lead SOIC

16-LEAD SOIC PACKAGE

AD825

TOP VIEW

NC

8

+V

7 6

OUTPUT NC

5

16 15 14 13 12 11 10

9

S

NC NC NC +V

S

OUTPUT NC NC NC

00876-E-001

00876-E-002

TJ = 150°C

1.0

0.5

MAXIMUM POWER DISSIPATION (W)

8-LEAD SOIC PACKAGE

0 –50 90–40–30–20–100 102030 5060708040

AMBIENT TEMPERATURE (°C)

Figure 6. Maximum Power Dissipation vs. Temperature

ESD CAUTION

ESD (electrostatic discharge) sensitive device. Electrostatic charges as high as 4000 V readily accumulate on the human body and test equipment and can discharge without detection. Although this product features proprietary ESD protection circuitry, permanent damage may occur on devices subjected to high energy electrostatic discharges. Therefore, proper ESD precautions are recommended to avoid performance degradation or loss of functionality.

00876-E-004

Rev. F | Page 5 of 12

AD825

TYPICAL PERFORMANCE CHARACTERISTICS

20

15

100

10

5

0

–5

OUTPUT SWING (V)

–10

–15

–20

0182

4 6 8 10 12 14 16

RL = 150Ω RL = 1kΩ

SUPPLY VOLTAGE (V)

Figure 7. Output Voltage Swing vs. Supply Voltage

15

10

VS = ±15V

5

VS = ±5V

0

–5

OUTPUT SWING (V)

–10

VS = ±15V

10

1

OUTPUT IMPEDANCE (Ω)

0.1

0.01 100 10M1k

00876-E-005

10k 100k 1M

FREQUENCY (Hz)

00876-E-008

Figure 10. Closed-Loop Output Impedance vs. Frequency

35

30

25

20

15

10

UNITY GAIN BANDWIDTH (MHz)

5

BANDWIDTH

PHASE MARGIN

80

60

40

PHASE MARGIN (°C)

–15

0 100

200 300 400 500 600 700 800 900 1000

LOAD RESISTANCE (Ω)

00876-E-006

Figure 8. Output Voltage Swing vs. Load Resistance

7.0

–40°

6.5

6.0

SUPPLY CURRENT (mA)

5.5

5.0 020

2

4 6 8 10 12 14 16 18

SUPPLY VOLTAGE (±V)

+25°

+85°

00876-E-007

Figure 9. Quiescent Supply Current vs. Supply Voltage

0

–60

–20 0 20 40 80 100 120

–40

Figure 11. Unity Gain Bandwidth and Phase Margin vs. Temperature

80

VS = ±15V

70

VS = ±5V

60

50

40

30

OPEN-LOOP GAIN (dB)

20

10

0

1k 100M10k

Figure 12. Open-Loop Gain and Phase Margin vs. Frequency

for Various Temperatures

TEMPERATURE (°C)

60

100k 1M 10M FREQUENCY (Hz)

140

20

180

135

90

45

0

00876-E-009

OPEN-LOOP PHASE (Degrees)

00876-E-010

Rev. F | Page 6 of 12

AD825

80

75

VS = ±15V

30

RL = 1kΩ

20

70

OPEN-LOOP GAIN (dB)

65

60

10 10k1k

LOAD RESISTANCE (Ω)

Figure 13. Open-Loop Gain vs. Load Resistance

10

0

–10

–20

–30

–40

PSR (dB)

–50

–60 –70

–80

–90

10k 10M100k

FREQUENCY (Hz)

Figure 14. Power Supply Rejection vs. Frequency

V

= ±5V

S

1M

–PSRR

+PSRR

RL = 150Ω

10

OUTPUT VOLTAGE (V p-p)

0 10k 100k

00876-E-011

FREQUENCY (Hz)

1M 10M

00876-E-014

Figure 16. Large Signal Frequency Response; G = +2

200

180

160

140

120

100

80

SETTLING TIME (ns)

60

40

20

0

00876-E-012

10 –108

0.01%

0.1%

6 4 2 0 –2 –4 –6 –8

OUTPUT SWING (0 to ±V)

0.01%

0.1%

00876-E-015

Figure 17. Output Swing and Error vs. Settling Time

130

120

110

100

90

80

CMR (dB)

70

60

50

40 30

100 10k 1M

10 10M1k

VS = ±5V

VS = ±15V

FREQUENCY (Hz)

100k

Figure 15. Commo n-Mode Re jection vs. Frequen cy

00876-E-013

Rev. F | Page 7 of 12

–50

–55

–60

–65

–70

DISTORTION (dB)

–75

–80

–85

100k 10M1M

FREQUENCY (Hz)

Figure 18. Harmonic Distortion vs. Frequency

SECOND

THIRD

00876-E-016

AD825

160

140

120

100

80

60

SLEW RATE (V/µs)

40

20

0

–60

±15V

±5V

–40

–20 0 20 40 80 100 120

TEMPERATURE (°C)

60

Figure 19. Slew Rate vs. Temperature

140

10µF

+V

S

0.01µF

7

HP PULSE (LS)

OR

FUNCTION (SS)

GENERATOR

2

AD825

V

IN

3

50Ω

6

4

0.01µF

10µF

–V

S

TEKTRONIX

OUT

P6204 FET

PROBE

R

L

V

TEKTRONIX

7A24

PREAMP

00876-E-020

Figure 22. Noninverting Amplifier Connection

00876-E-017

2

1

0

–1

–2

–3

GAIN (dB)

–4

V

IN

V

–5

–6

–7

–8

1k 100k 10M10k 1M

0.1dB FLATNESS

S

±5V

10MHz

±15V

21MHz

V

OUT

FREQUENCY (Hz)

Figure 20. Closed-Loop Gain vs. Frequency, Gain = +1

2

1

0

–1

–2

–3

V

IN

GAIN (dB)

–4

–5

V

–6 –7

–8

S

±5V ±15V

1k 100k 10M10k 1M

1kΩ1kΩ

0.1dB FLATNESS

7.7MHz

9.8MHz

FREQUENCY (Hz)

V

OUT

Figure 21. Closed-Loop Gain vs. Frequency, Gain = −1

5V

00876-E-018

Figure 23. Noninverting Large Signal Pulse Response, R

200mV

00876-E-019

Figure 24. Noninverting Small Signal Pulse Response, R

100ns

50ns

= 1 kΩ

L

= 1 kΩ

L

00876-E-021

00876-E-022

Rev. F | Page 8 of 12

AD825

5V

100ns

Figure 25. Noninverting Large Signal Pulse Response, R

200mV

50ns

= 150 Ω

L

5V

00876-E-023

5V

Figure 28. Inverting Large Signal Pulse Response, R

100ns

50ns200mV

= 1 kΩ

L

00876-E-026

200mV

Figure 26. Noninverting Small Signal Pulse Response, R

1kΩ

+V

10µF

S

0.01µF

HP PULSE

GENERATOR

V

IN

R

IN

1kΩ

50Ω

2

3

7

AD825

4

–V

S

0.01µF

10µF

6

V

OUT

Figure 27. Inverting Amplifier Connection

TEKTRONIX

P6204 FET

PROBE

R

L

00876-E-024

= 150 Ω

L

TEKTRONIX

7A24

PREAMP

200mV

Figure 29. Inverting Small Signal Pulse Response, R

= 1 kΩ

L

00876-E-027

00876-E-025

Rev. F | Page 9 of 12

AD825

DRIVING CAPACITIVE LOADS

The internal compensation of the AD825, together with its high output current drive, permits excellent large signal performance while driving extremely high capacitive loads.

1kΩ

+V

10µF

S

VPOS

NEG

POS

0.01µF

HP PULSE

GENERATOR

V

IN

R

IN

1kΩ

50Ω

2

3

7

AD825

4

–V

S

0.01µF

10µF

V

OUT

TEKTRONIX

P6204 FET

PROBE

C

L

6

TEKTRONIX

7A24

PREAMP

Figure 30. Inverting Amplifier Driving a Capacitive Load

INPUT

5V

OUTPUT

5V

500ns

Figure 31. Inverting Amplifier Pulse Response

While Driving a 400 pF Capacitive Load

THEORY OF OPERATION

The AD825 is a low cost, wideband, high performance FET input operational amplifier. With its unique input stage design, the AD825 ensures no phase reversal, even for inputs that exceed the power supply voltages, and its output stage is designed to drive heavy capacitive or resistive loads with small changes relative to no load conditions.

The AD825 (Figure 32) consists of common-drain, commonbase FET input stage driving a cascoded, common-base matched NPN gain stage. The output buffer stage uses emitter followers in a Class AB amplifier that can deliver large current to the load while maintaining low levels of distortion.

C

F

00876-E-028

VOUT

VNEG

00876-E-030

Figure 32. Simplified Schematic

The capacitor, CF, in the output stage, enables the AD825 to drive heavy capacitive loads. For light loads, the gain of the output buffer is close to unity, C

is bootstrapped, and not much

F

happens. As the capacitive load is increased, the gain of the output buffer is decreased and the bandwidth of the amplifier is reduced through a portion of C

adding to the dominant pole.

F

As the capacitive load is further increased, the amplifier’s bandwidth continues to drop, maintaining the stability of the AD825.

INPUT CONSIDERATION

00876-E-029

The AD825 with its unique input stage ensures no phase reversal for signals as large as or even larger than the supply voltages. Also, layout considerations of the input transistors ensure functionality even with a large differential signal.

The need for a low noise input stage calls for a larger FET transistor. One should consider the additional capacitance that is added to ensure stability. When filters are designed with the AD825, one needs to consider the input capacitance (5 pF to 6 pF) of the AD825 as part of the passive network.

GROUNDING AND BYPASSING

The AD825 is a low input bias current FET amplifier. Its high frequency response makes it useful in applications, such as photodiode interfaces, filters, and audio circuits. When designing high frequency circuits, some special precautions are in order. Circuits must be built with short interconnects, and resistances should have low inductive paths to ground. Power supply leads should be bypassed to common as close as possible to the amplifier pins. Ceramic capacitors of 0.1 µF are recommended.

Rev. F | Page 10 of 12

AD825

(

)

V

SECOND-ORDER LOW-PASS FILTER

A second-order Butterworth low-pass filter can be implemented using the AD825 as shown in Figure 33. The extremely low bias currents of the AD825 allow the use of large resistor values and, consequently, small capacitor values without concern for developing large offset errors. Low current noise is another factor in permitting the use of large resistors without having to worry about the resultant voltage noise.

With the values shown, the corner frequency will be 1 MHz. The equations for component selection are shown below. Note that the noninverting input (and the inverting input) has an input c apacit ance of 6 pF. As a resu lt, the calculated value of C1 (12 pF) is reduced to 6 pF.

C1

A plot of the filter frequency response is shown in Figure 34; better than 40 dB of high frequency rejection is provided.

414.1

π=2

CUTOFF

()

faradsC2

R1f

π=2

707.0

CUTOFF

R1f

Ωk100Ωk10 toTypicallySelectedUserR2R1 ==

C1

24pF

R1

9.31kΩR29.31kΩ

IN

6pF

C2

Figure 33. Second-Order Butterworth Low-Pass Filter

0

–10

–20

–30

–40

–50

–60

–70

HIGH FREQUENCY REJECTION (dB)

–80

10k 100M100k

Figure 34. Frequency Response of Second-Order Butterworth Filter

+5V

C3

0.1µF

AD825

C4

0.1µF

–5V

1M 10M

FREQUENCY (Hz)

V

OUT

00876-E-031

00876-E-032

Rev. F | Page 11 of 12

AD825

Y

OUTLINE DIMENSIONS

10.50 (0.4134)

10.10 (0.3976)

5.00 (0.1968)

4.80 (0.1890)

4.00 (0.1574)

3.80 (0.1497)

0.25 (0.0098)

0.10 (0.0040)

COPLANARIT

0.10

CONTROLLING DIMENSIONS ARE IN MILLIMETERS; INCH DIMENSIONS (IN PARENTHESES) ARE ROUNDED-OFF MILLIMETER EQUIVALENTS FOR REFERENCE ONLY AND ARE NOT APPROPRIATE FOR USE IN DESIGN

85

1.27 (0.0500)

SEATING

PLANE

COMPLIANT TO JEDEC STANDARDS MS-012AA

BSC

6.20 (0.2440)

5.80 (0.2284)

41

1.75 (0.0688)

1.35 (0.0532)

0.51 (0.0201)

0.31 (0.0122)

0.25 (0.0098)

0.17 (0.0067)

0.50 (0.0196)

0.25 (0.0099)

8°

1.27 (0.0500)

0°

0.40 (0.0157)

Figure 35. 8-Lead Standard Small Outline Package [SOIC]

Narrow Body (R-8)

Dimensions shown in millimeters (inches)

× 45°

16

1

1.27 (0.0500) BSC

0.30 (0.0118)

0.10 (0.0039)

COPLANARITY

0.10

CONTROLLING DIMENSIONS ARE IN MILLIMETERS; INCH DIMENSIONS (IN PARENTHESES) ARE ROUNDED-OFF MILLIMETER EQUIVALENTS FOR REFERENCE ONLY AND ARE NOT APPROPRIATE FOR USE IN DESIGN

0.51 (0.0201)

0.31 (0.0122)

COMPLIANT TO JEDEC STANDARDS MS-013AA

Figure 36. 16-Lead Standard Small Outline Package [SOIC]

Dimensions shown in millimeters (inches)

9

7.60 (0.2992)

7.40 (0.2913)

10.65 (0.4193)

8

10.00 (0.3937)

2.65 (0.1043)

2.35 (0.0925)

SEATING PLANE

0.33 (0.0130)

0.20 (0.0079)

Wide Body (R-16)

0.75 (0.0295)

0.25 (0.0098)

8° 0°

ORDERING GUIDE

Model Temperature Range Package Description Package Option

AD825AR −40°C to +85°C 8-Lead SOIC R-8 AD825AR-REEL −40°C to +85°C 8-Lead SOIC, 13" Tape and Reel R-8 AD825AR-REEL7 −40°C to +85°C 8-Lead SOIC, 7" Tape and Reel R-8 AD825AR-16 −40°C to +85°C 16-Lead SOIC R-16 AD825AR-16-REEL −40°C to +85°C 16-Lead SOIC, 13" Tape and Reel R-16 AD825AR-16-REEL7 −40°C to +85°C 16-Lead SOIC, 7" Tape and Reel R-16 AD825ARZ-16 AD825ARZ-16-REEL1 −40°C to +85°C 16-Lead SOIC, 13" Tape and Reel R-16 AD825ARZ-16-REEL71 −40°C to +85°C 16-Lead SOIC, 7" Tape and Reel R-16 AD825ACHIPS Die

1

Z = Pb-free part.

1

−40°C to +85°C 16-Lead SOIC R-16

× 45°

1.27 (0.0500)

0.40 (0.0157)

C00876–0 –10/04(F)

Rev. F | Page 12 of 12

Datasheet AD825 Datasheet (Analog Devices)

Specifications and Main Features

Frequently Asked Questions

User Manual

FEATURES

APPLICATIONS

CONNECTION DIAGRAMS

GENERAL DESCRIPTION

TABLE OF CONTENTS

SPECIFICATIONS

ABSOLUTE MAXIMUM RATINGS

PIN CONFIGURATIONS

ESD CAUTION

TYPICAL PERFORMANCE CHARACTERISTICS

DRIVING CAPACITIVE LOADS

THEORY OF OPERATION

INPUT CONSIDERATION

GROUNDING AND BYPASSING

SECOND-ORDER LOW-PASS FILTER

OUTLINE DIMENSIONS

ORDERING GUIDE