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General-Purpose, −55°C to +125°C,

Wide Bandwidth, DC-Coupled VGA

AD8336

Rev. C

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FEATURES

Low noise

Voltage noise: 3 nV/√Hz

Current noise: 3 pA/√Hz

Small-signal BW: 115 MHz

Large-signal BW: 2 V p-p = 80 MHz

Slew rate: 550 V/μs, 2 V p-p

Gain ranges (specified)

−14 dB to +46 dB

0 dB to 60 dB

Gain scaling: 50 dB/V

DC-coupled

Single-ended input and output

Supplies: ±3 V to ±12 V

Temperature range: −55°C to +125°C

Power

150 mW @ ±3 V, −55°C < T < +125°C

84 mW @ ±3 V, PWRA = 3 V

APPLICATIONS

Industrial process controls

High performance AGC systems

I/Q signal processing

Video

Industrial and medical ultrasound

Radar receivers

FUNCTIONAL BLOCK DIAGRAM

VOUT

PRAO

GNEG

AD8336

VCOMVPOS GPOS

34dBPrA

PWRA

ATTENUATOR

–60dB TO 0dB

GAIN CONTROL

INTERFACE

INPP

8 9

INPN

–

BIAS

06228-001

10 13 3 11 12

VNEG

Figure 1.

GENERAL DESCRIPTION

The AD8336 is a low noise, single-ended, linear-in-dB, general-

purpose variable gain amplifier, usable over a large range of supply

voltages. It features an uncommitted preamplifier (preamp) with

a usable gain range of 6 dB to 26 dB established by external

resistors in the classical manner. The VGA gain range is 0 dB to

60 dB, and its absolute gain limits are −26 dB to +34 dB. When

the preamplifier gain is adjusted for 12 dB, the combined 3 dB

bandwidth of the preamp and VGA is 100 MHz, and the amplifier

is fully usable to 80 MHz. With ±5 V supplies, the maximum

output swing is 7 V p-p.

Thanks to its X-Amp® architecture, excellent bandwidth uni-

formity is maintained across the entire gain range of the VGA.

Intended for a broad spectrum of applications, the differential

gain control interface provides precise linear-in-dB gain scaling

of 50 dB/V over the temperature span of −55°C to +125°C. The

differential gain control is easy to interface with a variety of

external circuits within the common-mode voltage limits of the

AD8336.

The large supply voltage range makes the AD8336 particularly

suited for industrial medical applications and for video circuits.

Dual-supply operation enables bipolar input signals, such as

those generated by photodiodes or photomultiplier tubes.

The fully independent voltage feedback preamp allows both

inverting and noninverting gain topologies, making it a fully

bipolar VGA. The AD8336 can be used within the specified

gain range of −14 dB to +60 dB by selecting a preamp gain

between 6 dB and 26 dB and choosing appropriate feedback

resistors. For the nominal preamp gain of 4×, the overall gain

range is −14 dB to +46 dB.

In critical applications, the quiescent power can be reduced by

about half by using the power adjust pin, PWRA. This is especially

useful when operating with high supply voltages of up to ±12 V,

or at high temperatures.

The operating temperature range is −55°C to +125°C. The

AD8336 is available in a 16-lead LFCSP (4 mm × 4 mm).

Summary of content (28 pages)

PAGE 1
General-Purpose, −55°C to +125°C, Wide Bandwidth, DC-Coupled VGA AD8336 Low noise Voltage noise: 3 nV/√Hz Current noise: 3 pA/√Hz Small-signal BW: 115 MHz Large-signal BW: 2 V p-p = 80 MHz Slew rate: 550 V/μs, 2 V p-p Gain ranges (specified) −14 dB to +46 dB 0 dB to 60 dB Gain scaling: 50 dB/V DC-coupled Single-ended input and output Supplies: ±3 V to ±12 V Temperature range: −55°C to +125°C Power 150 mW @ ±3 V, −55°C < T < +125°C 84 mW @ ±3 V, PWRA = 3 V FUNCTIONAL BLOCK DIAGRAM AD8336 INPP 4 + INPN 5
PAGE 2
AD8336 TABLE OF CONTENTS Features .............................................................................................. 1 VGA ............................................................................................. 20 Applications ....................................................................................... 1 Setting the Gain .......................................................................... 21 Functional Block Diagram .....................................................
PAGE 3
AD8336 SPECIFICATIONS VS = ±5 V, T = 25°C, gain range = −14 dB to +46 dB, preamp gain = 4×, f = 1 MHz, CL = 5 pF, RL = 500 Ω, PWRA = GND, unless otherwise specified. Table 1.
PAGE 4
AD8336 Parameter ABSOLUTE GAIN ERROR 2 GAIN CONTROL INTERFACE Gain Scaling Factor Intercept Gain Range Input Voltage (VGAIN) Range Input Current Response Time OUTPUT PERFORMANCE Output Impedance, DC to 10 MHz Output Signal Swing Output Current Short-Circuit Current Output Offset Voltage PWRA PIN Normal Power (Logic Low) Low Power (Logic High) Normal Power (Logic Low) Low Power (Logic High) Normal Power (Logic Low) Low Power (Logic High) POWER SUPPLY Supply Voltage Operating Range Quiescent Current VS = ±
PAGE 5
AD8336 ABSOLUTE MAXIMUM RATINGS Table 2. Parameter Supply Voltage (VPOS, VNEG) Input Voltage (INPP, INPN) Gain Voltage (GPOS, GNEG) PWRA VGAI Power Dissipation VS ≤ ±5 V ±5 V < VS ≤ ±12 V Operating Temperature Range ±3 V < VS ≤ ±10 V ±10 V < VS ≤ ±12 V Storage Temperature Range Lead Temperature (Soldering 60 sec) Thermal Data 1 θJA θJB θJC ΨJT ΨJB 1 Stresses above those listed under the Absolute Maximum Ratings may cause permanent damage to the device.
PAGE 6
AD8336 VPOS GNEG PWRA 16 15 14 13 12 PIN 1 INDICATOR 11 2 VCOM 3 10 VNEG AD8336 5 6 7 8 NC PRAO TOP VIEW 4 (Not to Scale) 9 NC INPP 1 INPN VOUT GPOS VGAI NOTES 1. NC = NO CONNECT. 2. THE EXPOSED PAD IS NOT CONNECTED INTERNALLY. FOR INCREASED RELIABILITY OF THE SOLDER JOINTS AND MAXIMUM THERMAL CAPABILITY, IT IS RECOMMENDED THAT THE PADDLE BE SOLDERED TO THE GROUND PLANE. 06228-002 NC NC NC PIN CONFIGURATION AND FUNCTION DESCRIPTIONS Figure 2. Pin Configuration Table 3.
PAGE 7
AD8336 TYPICAL PERFORMANCE CHARACTERISTICS VS = ±5 V, T = 25°C, gain range = −14 dB to +46 dB, preamp gain = 4×, f = 1 MHz, CL = 5 pF, RL = 500 Ω, PWRA = GND, unless otherwise specified. 50 2.0 T = +125°C T = +25°C T = –55°C 40 1.0 GAIN ERROR (dB) 20 10 0 –0.5 –400 –200 0 200 400 600 800 VGAIN (mV) –2.0 –800 06228-003 –600 Figure 3. Gain vs. VGAIN for Three Values of Temperature (T) (See Figure 56) –400 –200 0 200 VGAIN (mV) 400 600 800 Figure 6. Gain Error vs.
PAGE 8
AD8336 2.0 PREAMP GAIN = PREAMP GAIN = PREAMP GAIN = PREAMP GAIN = 1.5 50 4×, f = 1MHz 4×, f = 10MHz 20×, f = 1MHz 20×, f = 10MHz 60 UNITS VGAIN = –0.3V VGAIN = +0.3V 40 0.5 % OF UNITS GAIN ERROR (dB) 1.0 0 –0.5 30 20 –1.0 10 Figure 9. Gain Error vs. VGAIN at 1 MHz and 10 MHz and for Preamp Gains of 4× and 20× (See Figure 56) 2.0 GAIN ERROR (dB) Figure 12.
PAGE 9
AD8336 20 50 +0.5V –20 30 –40 GAIN (dB) –60 –80 –100 +0.2V 20 0V 10 –0.2V 0 –120 –0.5V –140 –10 –0.7V –160 –200 –0.8 VS = ±12V VS = ±5V VS = ±3V –0.6 –20 –0.4 –0.2 0 0.2 VGAIN (V) 0.4 0.6 0.8 –30 100k 50 VGAIN = +0.7V +0.5V 40 30 10 +0.2V 20 30 –200 –160 –120 –80 –40 OUTPUT OFFSET (mV) 0 40 GAIN (dB) 0 –240 80 0V 10 –0.2V 0 SAMPLE SIZE = 60 UNITS VGAIN = 0V 20 100M 200M Figure 18.
PAGE 10
AD8336 50 30 VGAIN = +0.7V +0.5V 40 25 30 GAIN = –19× 20 20 15 0V 10 GAIN (dB) GAIN (dB) +0.2V –0.2V GAIN = –3× 10 5 0 –0.5V –10 0 –5 –20 PREAMP GAIN = –3× 1M 10M FREQUENCY (Hz) 100M 200M 1M 10M FREQUENCY (Hz) 100M 500M Figure 24. Preamp Frequency Response for Three Values of Supply Voltage (VS) When the Inverting Gain Value is −3× or −19× (See Figure 69) Figure 21.
PAGE 11
AD8336 1k INPUT-REFERRED NOISE (nV/√Hz) 1k 10 1 0.1 VS = ±12V VS = ±5V VS = ±3V 100M 500M 1 –800 6 f = 5MHz INPUT-REFERRED NOISE (nV/√Hz) 700 600 500 400 300 100 0 –800 –600 –400 0 –200 200 VGAIN (mV) 400 = +125°C = +85°C = +25°C = –40°C = –55°C 600 800 Figure 28. Output-Referred Noise vs.
PAGE 12
AD8336 –40 HARMONIC DISTORTION (dBc) –45 10 INPUT-REFERRED NOISE RS THERMAL NOISE ALONE 100 1k SOURCE RESISTANCE (Ω) 10k –50 HD2 –55 HD3 –60 –65 –70 0 Figure 33. Input-Referred Noise vs. Source Resistance (See Figure 72) 70 –20 HARMONIC DISTORTION (dBc) 50 SIMULATED DATA 40 30 50Ω SOURCE –600 –400 –200 0 200 VGAIN (mV) 400 600 800 Figure 34. Noise Figure vs. VGAIN (See Figure 63) –40 HARMONIC DISTORTION (dBc) HD3 –60 600 800 1.0k 1.2k 1.4k 1.6k 1.8k 2.0k 2.
PAGE 13
AD8336 HD3 f = 5MHz 40 OUTPUT SWING OF PREAMP LIMITS MINIMUM USABLE VGAIN LEVELS 1MHz 500mV 1MHz 1V 10MHz 500mV 10MHz 1V 35 –30 OUTPUT IP3 (dBm) 30 –40 –50 –60 25 20 15 10 –80 –600 VOUT VOUT VOUT VOUT = 0.5V p-p = 1V p-p = 2V p-p = 4V p-p –400 –200 5 400 0 200 VGAIN (mV) 600 800 VOUT = 1V p-p VGAIN = 0V COMPOSITE INPUTS SEPARATED BY 100kHz 0 –800 Figure 39. Third Harmonic Distortion vs.
PAGE 14
AD8336 0 –0.2 VIN (mV) VOUT (mV) 0 –20 –0.4 0 50 100 150 TIME (ns) 200 250 300 –60 350 0.5 0 –5 –0.5 –1.5 –20 –2.0 –25 –100 20 50 250 300 –2.5 350 2.0 1.5 1.0 5 0.5 0 0 INPUT –10 –0.4 –40 –15 0 50 100 150 TIME (ns) 200 250 300 –60 350 –20 –100 2.5 VGAIN = 0.7V 1.0 5 0.5 0 0 –5 –0.5 –10 –1.0 –50 0 50 100 150 TIME (ns) 200 100 150 200 TIME (ns) 250 300 350 VOUT (V) –2.0 400 3 VGAIN = 0.
PAGE 15
AD8336 3 10 20 2 0 10 1 0 0 50 –30 –2 100 150 TIME (ns) 200 250 300 –50 –3 350 –60 100k Figure 51. Large-Signal Pulse Response for Various Values of Load Capacitance Using ±12 V Power Supplies (See Figure 65) VOLTAGE (V) 0.5 VOUT VGAIN –0.5 –2.5 –0.5 0 0.5 1.0 TIME (µs) 1.5 2.0 06228-052 –1.5 4 0.3 3 0.2 2 0.1 1 0 0 –0.1 –1 –0.2 –2 –0.3 OUTPUT VOLTAGE (V) 5 VGAIN = 0.7V 0.4 –3 VIN (V) VOUT (V) –4 –5 –6 –3 0 3 TIME (µs) 6 06228-053 –0.
PAGE 16
AD8336 TEST CIRCUITS NETWORK ANALYZER NETWORK ANALYZER OUT OUT IN 50Ω IN 50Ω 50Ω AD8336 5 1 49.9Ω 8 9 12 4 + 5 – PrA 11 1 8 301Ω 453Ω 9 12 11 301Ω 06228-056 VGAIN 100Ω 06228-059 49.9Ω AD8336 453Ω + PrA – 4 50Ω 100Ω Figure 56. Gain vs. VGAIN and Gain Error vs. VGAIN Figure 59. Group Delay NETWORK ANALYZER OUT IN 50Ω 50Ω 453Ω AD8336 49.
PAGE 17
AD8336 OSCILLOSCOPE PULSE GENERATOR SPECTRUM ANALYZER POWER SPLITTER OUT CH2 CH1 IN 50Ω 50Ω 50Ω AD8336 AD8336 + PrA – 4 5 1 OPTIONAL 20Ω 453Ω + PrA – 4 5 1 49.9Ω 8 8 9 12 11 12 11 0.7V 06228-065 100Ω 06228-062 VGAIN 100Ω 9 301Ω 301Ω Figure 62. Input-Referred Noise and Output-Referred Noise Figure 65.
PAGE 18
AD8336 POWER SUPPLIES CONNECTED TO NETWORK ANALYZER BIAS PORT NETWORK ANALYZER BENCH POWER SUPPLY DMM (+I) OUT IN 50Ω 13 AD8336 4 + 5 – PrA BYPASS CAPACITORS REMOVED FOR MEASUREMENT 1 VPOS OR VNEG AD8336 + PrA – 4 49.9Ω 8 9 50Ω 12 11 5 1 10 DIFFERENTIAL FET PROBE 301Ω 8 DMM (–I) 9 12 11 06228-068 301Ω VGAIN 100Ω Figure 68. Supply Current 06228-071 100Ω Figure 71.
PAGE 19
AD8336 SPECTRUM ANALYZER SIGNAL GENERATOR IN OUT 50Ω 50Ω OPTIONAL 20dB ATTENUATOR 22dB AD8336 453Ω 4 + 5 – PrA 49.9Ω 1 8 9 12 11 301Ω 06228-074 VGAIN 100Ω Figure 74. IP1dB vs. VGAIN SPECTRUM ANALYZER SIGNAL GENERATOR OUT IN 50Ω 50Ω –20dB AD8336 AMPLIFIER 49.9Ω 5 + PrA – 4 1 5 8 9 12 453Ω + – PrA 11 301Ω 1 8 9 12 11 301Ω 0.7V 100Ω VGAIN 100Ω 06228-075 4 AD8336 DUT 0Ω Figure 75. IP1dB vs.
PAGE 20
AD8336 THEORY OF OPERATION OVERVIEW PREAMPLIFIER The AD8336 is the first VGA designed for operation over exceptionally broad ranges of temperature and supply voltage. Its performance has been characterized from temperatures extending from −55°C to +125°C, and supply voltages from ±3 V to ±12 V. It is ideal for applications requiring dc coupling, large output voltage swings, very large gain ranges, extreme temperature variations, or a combination thereof.
PAGE 21
AD8336 SETTING THE GAIN NOISE The overall gain of the AD8336 is the sum (in decibels) or the product (magnitude) of the preamp gain and the VGA gain. The preamp gain is calculated as with any op amp, as seen in the Applications Information section. It is most convenient to think of the device gain in exponential terms (that is, in decibels) since the VGA responds linearly in decibels with changes in control voltage VGAIN at the gain pins. The noise of the AD8336 is dependent on the value of the VGA gain.
PAGE 22
AD8336 APPLICATIONS INFORMATION AMPLIFIER CONFIGURATION Circuit Configuration for Noninverting Gain The AD8336 amplifiers can be configured in various options. In addition to the 60 dB gain range variable gain stage, an uncommitted voltage gain amplifier is available to the user as a preamplifier. The preamplifier connections are separate to enable noninverting or inverting gain configurations or the use of interstage filtering.
PAGE 23
AD8336 Circuit Configuration for Inverting Gain USING THE POWER ADJUST FEATURE The preamplifier can also be used in an inverting configuration, as shown in Figure 81. The AD8336 has the provision to operate at lower power with a trade-off in bandwidth. The power reduction applies to the preamp and the VGA sections, and the bandwidth is reduced equally between them.
PAGE 24
AD8336 EVALUATION BOARD An evaluation board, AD8336-EVALZ, is available online for the AD8336. Figure 82 is a photo of the board. The board is shipped from the factory configured for a noninverting preamp gain of 4×. To change the value of the gain of the preamp or to change the gain polarity to inverting, alter the component values or install components in the alternate locations provided. All components are standard 0603 size, and the board is compliant with RoHS requirements.
PAGE 25
06228-088 06228-086 AD8336 Figure 87. Internal Power Plane Copper 06228-087 Figure 85. Component Side Silkscreen Figure 86. Internal Ground Plane Copper VPOS GND GND1 GND2 GND3 + L2 120nH R1 0Ω VOUT VOUTL VP R16 4.99kΩ CR1 5.1V 16 15 14 13 NC NC NC VPOS 1 LOW R3 0Ω VIN R2 49.9Ω C3 0.1µF VOUTD C8 0.1µF NORM VIN1 R5 VP VOUT 3 R4 0Ω R6 4 VCOM C6 1nF GNEG U1 POWER 2 PWRA AD8336 GPOS VNEG INPP VGAI GNEG R17 0Ω 12 R14 11 C5 9 0.
PAGE 26
AD8336 OUTLINE DIMENSIONS 4.00 BSC SQ 12° MAX 1.00 0.85 0.80 0.65 BSC TOP VIEW 3.75 BSC SQ 0.75 0.60 0.50 0.80 MAX 0.65 TYP 0.35 0.30 0.25 16 13 12 9 PIN 1 INDICATOR 1 2.25 2.10 SQ 1.95 8 5 4 0.25 MIN 1.95 BSC 0.05 MAX 0.02 NOM SEATING PLANE (BOTTOM VIEW) 0.20 REF COPLANARITY 0.08 FOR PROPER CONNECTION OF THE EXPOSED PAD, REFER TO THE PIN CONFIGURATION AND FUNCTION DESCRIPTIONS SECTION OF THIS DATA SHEET. COMPLIANT TO JEDEC STANDARDS MO-220-VGGC 072808-A PIN 1 INDICATOR 0.60 MAX 0.
PAGE 27
AD8336 NOTES Rev.