DATA SHEET
LMH6881 DC to 2.4-GHz, High-Linearity, Programmable Differential Amplifier
1 Features
2 Applications
- Oscilloscope Front End
- Spectrum Analyzer Gain Block
- Differential ADC Driver
- Differential Cable Driver
- IF/RF and Baseband Gain Blocks
- Medical Imaging
OIP3 vs Voltage Gain
3 Description
The LMH6881 is a high-speed, high-performance, programmable differential amplifier. With a bandwidth of 2.4 GHz and high linearity of 44 dBm OIP3, the LMH6881 is suitable for a wide variety of signal conditioning applications.
The LMH6881 programmable differential amplifier combines the best of both fully differential amplifiers and variable-gain amplifiers. The device offers superior noise and distortion performance over the entire gain range without external resistors, enabling the use of just one device and one design for multiple applications requiring different gain settings.
The LMH6881 is an easy-to-use amplifier that can replace both fully differential, fixed-gain amplifiers as well as variable-gain amplifiers. The LMH6881 requires no external gain-setting components and supports gain settings from 6 dB to 26 dB with small, accurate 0.25-dB gain steps. With an input impedance of 100 Ω, the LMH6881 is easy to drive from a variety of sources such as mixers or filters. The LMH6881 also supports 50-Ω single-ended signal sources and supports both DC- and AC-coupled applications.
Parallel gain control allows the LMH6881 to be soldered down in a fixed-gain so that no control circuit is required. If dynamic-gain control is desired, the LMH6881 can be changed with SPI™ serial commands or with the parallel pins.
The LMH6881 is fabricated in TI’s CBiCMOS8 proprietary complementary silicon germanium process and is available in a space-saving, thermally enhanced 24-pin lead quad WQFN package. The same amplifier is offered in a dual package as the LMH6882.
Device Information(1)
| PART NUMBER | PACKAGE | BODY SIZE (NOM) |
|---|---|---|
| LMH6881 | WQFN (24) | 4.00 mm × 4.00 mm |
- For all available packages, see the orderable addendum at the end of the data sheet.
4 Revision History
Changes from E Revision (March 2013) to F Revision
- Added Pin Configuration and Functions section, ESD Ratings table, Feature Description section, Device Functional Modes, Application and Implementation section, Power Supply Recommendations section, Layout section, Device and Documentation Support section, and Mechanical, Packaging, and Orderable Information section Go
5 Pin Configuration and Functions
RTW Package
24-Pins WQFN
Top View
Pin Functions
| PIN | TYPE | DESCRIPTION | |
|---|---|---|---|
| NO. | NAME | ||
| 1 | NC | — | |
| 2 | OCM | I | Output Common Mode, gain of 2 |
| 3 | D1, SDI | I | Parallel mode = Logic control signal, position 1 or weight 21
SPI mode = serial data in (SDI) |
| 4 | D0, SDO | I/O | Parallel mode = Logic control signal, position 0 or weight 20
SPI mode = serial data out (SDO) |
| 5 | SPI | I | Serial mode control |
| 6 | GND | I/O | Ground |
| 7 | GND | I/O | Ground |
| 8 | INMS | I | Amplifier single-ended input minus swing (negative) |
| 9 | INMD | I | Amplifier differential input minus swing (negative) |
| 10 | INPD | I | Amplifier differential input plus swing (positive) |
| 11 | INPS | I | Amplifier single-ended input plus swing (positive) |
| 12 | GND | I/O | Ground |
| 13 | GND | I/O | Ground |
| 14 | NC | — | |
| 15 | D2 | I | Parallel mode = Logic control signal, position 2 or weight 22 SPI mode = serial clock (CLK) |
| 16 | D3 | I | Parallel mode = Logic control signal, position 3 or weight 23 SPI mode = chip select (CS) |
| 17 | SD | I | Device Shutdown |
| 18 | NC | — | |
| 19 | VCC | I/O | Power supply nominal value of 5 V |
| 20 | VCC | I/O | Power supply nominal value of 5 V |
| 21 | OUTM | O | Amplifier output minus (negative) |
| 22 | OUTP | O | Amplifier output plus (positive) |
| 23 | VCC | I/O | Power supply nominal value of 5 V |
| 24 | VCC | I/O | Power supply nominal value of 5 V |
Pin Descriptions
| NO. | SYMBOL | PIN CATEGORY | DESCRIPTION |
|---|---|---|---|
| ANALOG I/O | |||
| 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 |
| POWER | |||
| 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. The exposed thermal pad is internally bonded to the ground pins. |
| 19, 20, 23, 24 | VCC | Power | Power supply pins. Valid power supply range is 4.75 V to 5.25 V. |
| Exposed Center Pad | Thermal/ Ground | Thermal management/ Ground | |
| DIGITAL INPUTS | |||
| 5 | SPI | Digital Input | 0 = Parallel Mode, 1 = Serial Mode |
| PARALLEL MODE DIGITAL PINS, SPI = LOGIC LOW | |||
| 3, 4, 15, 16 | D0, D1, D2, D3 | Digital Input | Attenuator control |
| 17 | SD | Digital Input | Shutdown 0 = amp on, 1 = amp off |
| SERIAL MODE DIGITAL PINS, SPI= LOGIC HIGH, SPI COMPATIBLE | |||
| 4 | SDO | Digital Output - Open Emitter | Serial Data Output (Requires external bias.) |
| 3 | SDI | Digital Input | Serial Data In |
| 16 | CS | Digital Input | Chip Select (active low) |
| 15 | CLK | Digital Input | Clock |
6 Specifications
6.1 Absolute Maximum Ratings(1)(2)
| MIN | MAX | UNIT | ||
|---|---|---|---|---|
| Positive Supply Voltage (VCC) | −0.6 | 5.5 | V | |
| Differential Voltage between Any Two Grounds | < 200 | mV | ||
| Analog Input Voltage Range | −0.6 | 5.5 | V | |
| Digital Input Voltage Range | −0.6 | 5.5 | V | |
| Output Short Circuit Duration (one pin to ground) | Infinite | |||
| Junction Temperature | 150 | °C | ||
| Soldering Information | Infrared or Convection (30 sec) | 260 | °C | |
| Storage temperature range, Tstg | −65 | 150 | °C | |
(1) Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. These are stress ratings only, which do not imply functional operation of the device at these or any other conditions beyond those indicated under Recommended Operating Conditions. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability.
(2) If Military/Aerospace specified devices are required, please contact the Texas Instruments Sales Office/ Distributors for availability and specifications.
6.2 ESD Ratings
| VALUE | UNIT | |||
|---|---|---|---|---|
| V(ESD) | Electrostatic discharge | Human body model (HBM), per ANSI/ESDA/JEDEC JS-001(1) | ±1000 | V |
| Charged-device model (CDM), per JEDEC specification JESD22-C101(2) | ±250 | |||
(1) JEDEC document JEP155 states that 500-V HBM allows safe manufacturing with a standard ESD control process.
(2) JEDEC document JEP157 states that 250-V CDM allows safe manufacturing with a standard ESD control process.
6.3 Recommended Operating Conditions
over operating free-air temperature range (unless otherwise noted)| MIN | MAX | UNIT | |||
|---|---|---|---|---|---|
| Supply Voltage (VCC) | 4.75 | 5.25 | V | ||
| Differential Voltage Between Any Two Grounds | < 10 | mV | |||
| Analog Input Voltage Range, AC Coupled | 0 | VCC | V | ||
| Temperature Range(1) | −40 | 85 | °C | ||
(1) The maximum power dissipation is a function of TJ(MAX), θJA and the ambient temperature TA. The maximum allowable power dissipation at any ambient temperature is PD = (TJ(MAX) – TA)/ θJA. All numbers apply for packages soldered directly onto a PC Board.
6.4 Thermal Information
| THERMAL METRIC(1) | LMH6881 | UNIT | |
|---|---|---|---|
| RTW (WQFN) | |||
| 24 PINS | |||
| RθJA | Junction-to-ambient thermal resistance | 38.1 | °C/W |
| RθJC(top) | Junction-to-case (top) thermal resistance | 39.9 | |
| RθJB | Junction-to-board thermal resistance | 16.7 | |
| ψJT | Junction-to-top characterization parameter | 0.5 | |
| ψJB | Junction-to-board characterization parameter | 16.8 | |
| RθJC(bot) | Junction-to-case (bottom) thermal resistance | 5.8 | |
(1) For more information about traditional and new thermal metrics, see the IC Package Thermal Metrics application report, SPRA953.
6.5 Electrical Characteristics(1)(4)(5)
The following specifications apply for single supply with VCC = 5 V, Maximum Gain (26 dB), RL = 200 Ω, fin = 100 MHz.| TEST CONDITIONS | MIN(3) | TYP(2) | MAX(3) | UNIT | ||
|---|---|---|---|---|---|---|
| DYNAMIC PERFORMANCE | ||||||
| 3 dBBW | −3-dB Bandwidth | VOUT= 2 VPPD | 2.4 | GHz | ||
| NF | Noise Figure | Source Resistance (Rs) = 100 Ω | 9.7 | dB | ||
| OIP3 | Output Third Order Intercept Point(7) | f = 100 MHz, POUT = 4 dBm per tone, tone spacing = 1 MHz | 44 | dBm | ||
| f = 200 MHz, POUT = 4 dBm per tone, tone spacing = 2 MHz | 42 | |||||
| OIP2 | Output Second Order Intercept Point | POUT= 4 dBm per Tone, f1 =112.5 MHz, f2 = 187.5 MHz | 76 | dBm | ||
| IMD3 | Third Order Intermodulation Products | f = 100 MHz, POUT = 4 dBm per tone, tone spacing = 1 MHz | −80 | dBc | ||
| f = 200 MHz, POUT = 4 dBm per tone, tone spacing =2 MHz | −76 | |||||
| P1dB | 1dB Compression Point | Output Power | 17 | dBm | ||
| HD2 | Second Order Harmonic Distortion | f = 200 MHz, POUT = 4 dBm | −70 | dBc | ||
| HD3 | Third Order Harmonic Distortion | f = 200 MHz, POUT = 4 dBm | −76 | dBc | ||
| CMRR | Common Mode Rejection Ratio(6) | Pin = −15 dBm, f = 100 MHz | −40 | dBc | ||
| SR | Slew Rate | 6000 | V/us | |||
| Output Voltage Noise | Maximum Gain f > 1 MHz | 47 | nV/√Hz | |||
| Input Referred Voltage Noise | Maximum Gain f > 1 MHz | 2.3 | nV/√Hz | |||
| ANALOG I/O | ||||||
| RIN | Input Resistance | Differential, INPD to INMD | 100 | Ω | ||
| RIN | Input Resistance | Single Ended, INPS or INPD, 50-Ω termination on unused input | 50 | Ω | ||
| VICM | Input Common Mode Voltage | Self Biased | 2.5 | V | ||
| Maximum Input Voltage Swing | Volts peak to peak, differential | 2.85 | VPPD | |||
| Maximum Differential Output Voltage Swing | Differential, f < 10 MHz | 6 | VPPD | |||
| ROUT | Output Resistance | Differential, f = 100 MHz | 0.4 | Ω | ||
| GAIN PARAMETERS | ||||||
| Maximum Voltage Gain | Parallel Inputs (INPD and INMD), Rs = 100 Ω | 26 | dB | |||
| Single-ended input (INMS or INPS), 50-Ω Rs and 50-Ω termination on unused input. | 26.6 | |||||
| Minimum Gain | Parallel Inputs, Rs = 100 Ω | 6 | dB | |||
| Gain Steps | Available using SPI interface | 80 | ||||
| Available using parallel interface | 10 | |||||
| Gain Step Size | Available using SPI interface | 0.25 | dB | |||
| Available using parallel interface | 2 | |||||
| Gain Step Error | Any two adjacent steps over entire range | ±0.125 | dB | |||
| Gain Step Phase Shift | Any two adjacent steps over entire range | ±3 | Degrees | |||
| Gain Step Switching Time | 20 | ns | ||||
| Enable/ Disable Time | Settled to 90% level | 15 | ns | |||
| POWER REQUIREMENTS | ||||||
| ICC | Supply Current | 100 | 135 | mA | ||
| P | Power | 0.5 | W | |||
| ICCD | Disabled Supply Current | 15 | mA | |||
| ALL DIGITAL INPUTS | ||||||
| Logic Compatibility | TTL, 2.5-V CMOS, 3.3-V CMOS, 5-V CMOS | |||||
| VIL | Logic Input Low Voltage | 0.4 | V | |||
| VIH | Logic Input High Voltage | 2.0 - 5.0 | V | |||
| IIH | Logic Input High Input Current | −9 | μA | |||
| IIL | Logic Input Low Input Current | −47 | μA | |||
| PARALLEL MODE TIMING | ||||||
| tGS | Setup Time | 3 | ns | |||
| tGH | Hold Time | 3 | ns | |||
| SERIAL MODE | ||||||
| fCLK | SPI Clock Frequency | 50% duty cycle | 10 | 50 | MHz | |
(1) Electrical Table values apply only for factory testing conditions at the temperature indicated. No verification of parametric performance is indicated in the electrical tables under conditions different than those tested
(2) Typical values represent the most likely parametric norm as determined at the time of characterization. Actual typical values may vary over time and will also depend on the application and configuration. The typical values are not tested and are not ensured on shipped production material.
(3) Limits are 100% production tested at 25°C. Limits over the operating temperature range are ensured through correlation using Statistical Quality Control (SQC) methods.
(4) Negative input current implies current flowing out of the device.
(5) Drift determined by dividing the change in parameter at temperature extremes by the total temperature change.
(6) CMRR is defined as the differential response at the output in response to a common mode signal at the input.
(7) OIP3 is the third order intermodulation intercept point. In this data sheet OIP3 numbers are single power measurements where OIP3 = IMD3 / 2 + POUT (per tone). OIP2 is the second order intercept point where OIP2 = IMD2 + POUT (per tone). HD2 is the second order harmonic distortion and is a single tone measurement. HD3 is the third order harmonic distortion and is a single tone measurement. Power measurements are made at the amplifier output pins.
6.6 Typical 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.
Figure 1. Frequency Response over Gain Range, 4-dB Steps
Figure 3. OIP3 vs Output Power
Figure 5. OIP3 vs Frequency
Figure 7. OIP3 vs Temperature
Figure 9. Supply Current vs Temperature
| Pout = 4 dBm |
Figure 13. HD2 and HD3 vs Voltage Gain
Figure 15. HD3 vs Output Power
Figure 17. Gain Step Amplitude Error
Figure 19. Cumulative Amplitude Error
Figure 21. Noise Figure vs Voltage Gain
Figure 23. Channel Enable Control Timing Behavior
Figure 25. 8-dB Step Control Timing Behavior
Figure 27. Input Impedance
Figure 29. OIP3 Overvoltage Gain Range
Figure 2. OIP3 vs Voltage Gain
Figure 4. Dynamic Range Figure vs Voltage Gain
Figure 6. OIP3 vs Supply Voltage
Figure 8. OIP2 vs Voltage Gain
Figure 10. Maximum Voltage Gain vs Temperature
| Pout = 4 dBm |
Figure 14. HD2 vs Output Power
Figure 16. Output Power vs Input Power
Figure 18. Gain Step Phase Error
Figure 20. Cumulative Phase Error
Figure 22. Noise Figure vs Frequency
Figure 24. 16-dB Gain Control Timing Behavior
Figure 26. Common Mode Rejection (Sdc21) vs Frequency
Figure 28. Output Impedance
Figure 30. Noise Figure Overvoltage Gain Range DVGA Response Shown for Comparison
6.6.1 Single-Ended Input
(Unless otherwise specified, the following conditions apply: TA = 25°C, VCC = 5 V, RL = 200 Ω, Maximum Gain.)
Figure 31. OIP3 vs Voltage Gain
| Pout = 4 dBm |
Figure 35. Noise Figure vs Voltage Gain
| Pout = 4 dBm | ||
| f = 100 MHz | Pout = 4 dBm |
Figure 36. Single-Ended Input Impedance
