Datasheet

ManualsBrandsTEXAS INSTRUMENTS ManualsLinear ICsLinear IC - Op-amp, differential amplifier Differential WQFN 24 (4x4)

6 8 10 12 14 16 18 20 22 24 26

OIP3 (dBm)

VOLTAGE GAIN (dB)

f = 100 MHz

OUT

= 4dBm / Tone

6 8 10 12 14 16 18 20 22 24 26

NOISE FIGURE (dB)

VOLTAGE GAIN (dB)

LMH6881

Traditional DVGA

LMH6881

www.ti.com

SNOSC72E –JUNE 2012–REVISED MARCH 2013

LMH6881 DC to 2.4GHz, High Linearity, Programmable Differential Amplifier

Check for Samples: LMH6881

The LMH6881 programmable differential amplifier

FEATURES

combines the best of both fully differential amplifiers

• Small Signal Bandwidth: 2400 MHz

and variable gain amplifiers. It offers superior noise

• OIP3 @ 100 MHz: 44 dBm

and distortion performance over the entire gain range

without external resistors, enabling the use of just

• HD3 @ 100 MHz: −100 dBc

one device and one design for multiple applications

• Noise Figure: 9.7 dB

requiring different gain settings.

• Voltage Gain Range: 26 dB to 6 dB

The LMH6881 is an easy-to-use amplifier that can

• Voltage Gain Step Size 0.25 dB

replace both fully differential, fixed gain amplifiers as

• Input Impedance 100 Ω

well as variable gain amplifiers. The LMH6881

requires no external gain-setting components and

• Parallel and Serial Gain Control

supports gain settings from 6 dB to 26 dB with small,

• Power Down Capability

accurate 0.25-dB gain steps. With an input

impedance of 100 Ω the LMH6881 is easy to drive

APPLICATIONS

from a variety of sources such as mixers or filters.

The LMH6881 also supports 50 Ω single-ended

• Oscilloscope Front End

signal sources and supports both DC- and AC-

• Spectrum Analyzer Gain Block

coupled applications.

• Differential ADC Driver

Parallel gain control allows the LMH6881 to be

• Differential Cable Driver

soldered down in a fixed gain so that no control

• IF / RF and Baseband Gain Blocks

circuit is required. If dynamic-gain control is desired,

the LMH6881 can be changed with SPI™ serial

• Medical Imaging

commands or with the parallel pins.

DESCRIPTION

The LMH6881 is fabricated in TI’s CBiCMOS8

The LMH6881 is a high-speed, high-performance, proprietary complementary silicon germanium

programmable differential amplifier. With a bandwidth process and is available in a space saving, thermally

of 2.4 GHz and high linearity of 44 dBm OIP3, the enhanced 24-pin Lead Quad WQFN package. The

LMH6881 is suitable for a wide variety of signal same amplifier is offered in a dual package as the

conditioning applications. LMH6882.

Performance Curves

Noise Figure Over Voltage Gain Range

OIP3 over Voltage Gain Range DVGA Response Shown for Comparison

Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of

Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.

2SPI is a trademark of Motorola, Inc..

3All other trademarks are the property of their respective owners.

PRODUCTION DATA information is current as of publication date.

Products conform to specifications per the terms of the Texas

Instruments standard warranty. Production processing does not

necessarily include testing of all parameters.

Summary of content (29 pages)

PAGE 1
LMH6881 www.ti.com SNOSC72E – JUNE 2012 – REVISED MARCH 2013 LMH6881 DC to 2.4GHz, High Linearity, Programmable Differential Amplifier Check for Samples: LMH6881 FEATURES 1 • • • • • • • • • 23 Small Signal Bandwidth: 2400 MHz OIP3 @ 100 MHz: 44 dBm HD3 @ 100 MHz: −100 dBc Noise Figure: 9.7 dB Voltage Gain Range: 26 dB to 6 dB Voltage Gain Step Size 0.
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LMH6881 SNOSC72E – JUNE 2012 – REVISED MARCH 2013 www.ti.com These devices have limited built-in ESD protection. The leads should be shorted together or the device placed in conductive foam during storage or handling to prevent electrostatic damage to the MOS gates. Absolute Maximum Ratings (1) (2) ESD Tolerance (3) Human Body Model 1 kV Charged Device Model 250V −0.6V to 5.5V Positive Supply Voltage (VCC) Differential Voltage between Any Two Grounds <200 mV Analog Input Voltage Range −0.6V to 5.
PAGE 3
LMH6881 www.ti.com SNOSC72E – JUNE 2012 – REVISED MARCH 2013 5V Electrical Characteristics (1) (2) (3) The following specifications apply for single supply with VCC = 5 V, Maximum Gain (26 dB), RL = 200 Ω, fin = 100 MHz. Boldface limits apply at temperature extremes. Symbol Parameter Conditions Min (4) Typ (5) Max (4) Units Dynamic Performance 3 dBBW −3 dB Bandwidth VOUT= 2 VPPD 2.4 NF Noise Figure Source Resistance (Rs) = 100 Ω 9.
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LMH6881 SNOSC72E – JUNE 2012 – REVISED MARCH 2013 www.ti.com 5V Electrical Characteristics(1)(2)(3) (continued) The following specifications apply for single supply with VCC = 5 V, Maximum Gain (26 dB), RL = 200 Ω, fin = 100 MHz. Boldface limits apply at temperature extremes. Symbol Parameter Min (4) Conditions Typ (5) Max (4) Units Gain Step Error Any two adjacent steps over entire range ±0.
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LMH6881 www.ti.com SNOSC72E – JUNE 2012 – REVISED MARCH 2013 CONNECTION DIAGRAM NC OCM D1 D0 SPI GND 24-Pin WQFN 1 GND VCC INMS VCC INMD OUTP GND NC VCC SD GND D3 VCC D2 INPS NC OUTM GND INPD Figure 1.
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LMH6881 SNOSC72E – JUNE 2012 – REVISED MARCH 2013 www.ti.com PIN DESCRIPTIONS Pin Number Symbol Pin Category Description 9,10 INPD, INMD Analog Input Differential inputs 100 Ω 8, 11 INPS, INMS Analog Input Single-ended inputs 50 Ω 21, 22 OUTP, OUTM Analog Output Differential outputs, low impedance 6, 7, 12, 13 GND Ground Ground pins. Connect to low impedance ground plane. All pin voltages are specified with respect to the voltage on these pins.
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LMH6881 www.ti.
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LMH6881 SNOSC72E – JUNE 2012 – REVISED MARCH 2013 www.ti.com Typical Performance Characteristics (Unless otherwise specified, the following conditions apply: TA = 25°C, VCC = 5 V, RL = 200 Ω, Maximum Gain, Differential Input). LMH6882 devices have been used for some typical performance plots.
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LMH6881 www.ti.com SNOSC72E – JUNE 2012 – REVISED MARCH 2013 Typical Performance Characteristics (continued) (Unless otherwise specified, the following conditions apply: TA = 25°C, VCC = 5 V, RL = 200 Ω, Maximum Gain, Differential Input). LMH6882 devices have been used for some typical performance plots. OIP3 vs Temperature OIP2 vs Voltage Gain 90 50 f = 100 MHz POUT= 4dBm / Tone 85 80 OIP2 (dBm) OIP3 (dBm) 45 40 35 75 70 65 60 Temperature - 40 °C 25 °C 85 °C 30 25 6 f1= 187.5 MHz f2= 112.
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LMH6881 SNOSC72E – JUNE 2012 – REVISED MARCH 2013 www.ti.com Typical Performance Characteristics (continued) (Unless otherwise specified, the following conditions apply: TA = 25°C, VCC = 5 V, RL = 200 Ω, Maximum Gain, Differential Input). LMH6882 devices have been used for some typical performance plots.
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LMH6881 www.ti.com SNOSC72E – JUNE 2012 – REVISED MARCH 2013 Typical Performance Characteristics (continued) (Unless otherwise specified, the following conditions apply: TA = 25°C, VCC = 5 V, RL = 200 Ω, Maximum Gain, Differential Input). LMH6882 devices have been used for some typical performance plots. Cumulative Amplitude Error 0.6 50 MHz 200 MHz 2 PHASE ERROR (Degrees) 0.5 0.4 0.3 0.2 0.1 0.0 -0.1 1 0 -1 -2 -3 -0.2 -4 -0.
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LMH6881 SNOSC72E – JUNE 2012 – REVISED MARCH 2013 www.ti.com Typical Performance Characteristics (continued) (Unless otherwise specified, the following conditions apply: TA = 25°C, VCC = 5 V, RL = 200 Ω, Maximum Gain, Differential Input). LMH6882 devices have been used for some typical performance plots.
PAGE 13
LMH6881 www.ti.com SNOSC72E – JUNE 2012 – REVISED MARCH 2013 Typical Performance Characteristics, Single-Ended Input (Unless otherwise specified, the following conditions apply: TA = 25°C, VCC = 5 V, RL = 200 Ω, Maximum Gain.
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LMH6881 SNOSC72E – JUNE 2012 – REVISED MARCH 2013 www.ti.com APPLICATION INFORMATION INTRODUCTION The LMH6881 has been designed to replace traditional, fixed-gain amplifiers, as well as variable-gain amplifiers, with an easy-to-use device which can be flexibly configured to many different gain settings while maintaining excellent performance over the entire gain range. Many systems can benefit from this programmable-gain, DCcapable, differential amplifier.
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LMH6881 www.ti.com SNOSC72E – JUNE 2012 – REVISED MARCH 2013 +5V 0.01 PF SOURCE LOAD VCC INMS 50: 49.9: OUT+ INMD VCM 2.5V AC VCM 2.5V LMH6881 INPD 100: OUT- 50: 49.9: INPS OCM 0.01 PF 1.25V Figure 38. Typical Implementation with a Differential Input Signal +5V 0.01 PF SOURCE LOAD 50: VIN 2.5V INMS VCC OUT+ INMD 49.9: AC VCM 2.5V LMH6881 INPD 100: OUT- INPS 49.9: 50: 0.01 PF OCM 0.01 PF 2.5V 1.25V Figure 39.
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LMH6881 SNOSC72E – JUNE 2012 – REVISED MARCH 2013 www.ti.com OUTPUT CHARACTERISTICS The LMH6881 has a low-impedance output very similar to a traditional Op-amp output. This means that a wide range of loads can be driven with good performance. Matching load impedance for proper termination of filters is as easy as inserting the proper value of resistor between the filter and the amplifier (See Figure 36 for example.) This flexibility makes system design and gain calculations very easy.
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LMH6881 www.ti.com SNOSC72E – JUNE 2012 – REVISED MARCH 2013 POWER GAIN AT LOAD (dB) 24 22 20 18 16 14 12 0 100 200 300 LOAD IMPEDANCE ( ) 400 Figure 41. Power Gain as a Function of the Load Printed circuit board (PCB) design is critical to high-frequency performance. In order to ensure output stability the load-matching resistors should be placed as close to the amplifier output pins as possible. This allows the matching resistors to mask the board parasitics from the amplifier output circuit.
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LMH6881 SNOSC72E – JUNE 2012 – REVISED MARCH 2013 www.ti.com Table 1. Filter Component Values (1) Center Frequency 75 MHz 150 MHz 180 MHz 250 MHz Bandwidth 40 MHz 60 MHz 75 MHz 100 MHz R1, R2 90 Ω 90 Ω 90 Ω 90 Ω L1, L2 390 nH 370 nH 300 nH 225 nH C1, C2 10 pF 3 pF 2.7 pF 1.
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LMH6881 www.ti.com SNOSC72E – JUNE 2012 – REVISED MARCH 2013 LMH6881 N/C INSP ROUT 100: RT OUTM INDP 100: V=1.25V V =2.5V 100: OUTP INDM CM ROUT INSM 100: RT +1.25V x2 N/C ADC12D1800RF 100: OCM Figure 44. DC-Coupled ADC Driver Example 2, Terminated Input ADC DIGITAL CONTROL OF THE GAIN AND POWER-DOWN PINS The LMH6881 will support two modes of control for its gain: a parallel mode and a serial mode (SPI compatible).
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LMH6881 SNOSC72E – JUNE 2012 – REVISED MARCH 2013 www.ti.com PARALLEL INTERFACE Parallel mode offers the fastest gain update capability with the drawback of requiring the most board space dedicated to control lines. To place the LMH6881 into parallel mode the SPI pin (pin 5) is set to the logical zero state. Alternately the SPI pin can be connected directly to ground. The SPI pin has a weak internal resistor to ground. If left unconnected, the amplifier will operate in parallel mode.
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LMH6881 www.ti.com SNOSC72E – JUNE 2012 – REVISED MARCH 2013 LMH6881 CONTROL LOGIC Shutdown SD 2 dB Step D0 4 dB Step D1 8 dB Step D2 16 dB Step D3 Figure 45. Parallel Mode Connection SPI-COMPATIBLE SERIAL INTERFACE The serial interface allows a great deal of flexibility in gain programming and reduced board complexity. The LMH6881 serial interface is a generic 4-wire synchronous interface that is compatible with SPI-type interfaces that are used on many microcontrollers and DSP controllers.
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LMH6881 SNOSC72E – JUNE 2012 – REVISED MARCH 2013 www.ti.com Table 4. SPI Registers Address Read/Write Name Description Default value [Hex] 0 R Revision ID Revision of the product 1 (first revision) 1 R Product ID Identification of the product 20 2 R/W Power down Power up/down of the amplifier 0 3 R/W Attenuation Attenuation control 50 Table 5. Register 2 Definition 7 6 5 4 3 2 Reserved 1 OFF = 1,1: ON = 0,0 0 Reserved Table 6.
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LMH6881 www.ti.com SNOSC72E – JUNE 2012 – REVISED MARCH 2013 Control Logic LMH6881 CLK CS SDI Clock out Chip Select out Data Out (MOSI) Data In (MISO) SDO R 10 mA Typ For SDO (MISO) pin only: VOH = R x 0.010A, VOL = 0V Recommended: R = 250: to 400: Figure 47. Internal Operation of the SDO pin FIGURE OF MERIT: DYNAMIC RANGE FIGURE The dynamic range figure (DRF) as illustrated in Figure 5, is defined as the input third order intercept point (IIP3) minus the noise figure (NF).
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LMH6881 SNOSC72E – JUNE 2012 – REVISED MARCH 2013 www.ti.com THERMAL CONSIDERATION The LMH6881 is packaged in a thermally enhanced package. The exposed pad on the bottom of the package is the primary means of removing heat from the package. It is recommended, but not necessary, that the exposed pad be connected to the supply ground plane. In any case, the thermal dissipation of the device is largely dependent on the attachment of the exposed pad to the system PCB.
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PACKAGE OPTION ADDENDUM www.ti.
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PACKAGE MATERIALS INFORMATION www.ti.com 21-Mar-2013 TAPE AND REEL INFORMATION *All dimensions are nominal Device Package Package Pins Type Drawing LMH6881SQ/NOPB WQFN RTW 24 LMH6881SQE/NOPB WQFN RTW LMH6881SQX/NOPB WQFN RTW SPQ Reel Reel A0 Diameter Width (mm) (mm) W1 (mm) B0 (mm) K0 (mm) P1 (mm) W Pin1 (mm) Quadrant 1000 178.0 12.4 4.3 4.3 1.3 8.0 12.0 Q1 24 250 178.0 12.4 4.3 4.3 1.3 8.0 12.0 Q1 24 4500 330.0 12.4 4.3 4.3 1.3 8.0 12.
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PACKAGE MATERIALS INFORMATION www.ti.com 21-Mar-2013 *All dimensions are nominal Device Package Type Package Drawing Pins SPQ Length (mm) Width (mm) Height (mm) LMH6881SQ/NOPB WQFN RTW 24 1000 210.0 185.0 35.0 LMH6881SQE/NOPB WQFN RTW 24 250 210.0 185.0 35.0 LMH6881SQX/NOPB WQFN RTW 24 4500 367.0 367.0 35.
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MECHANICAL DATA RTW0024A SQA24A (Rev B) www.ti.
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