LMH6518
- Gain range: 40dB
- Gain step size: 2dB
- Combined gain resolution with GSPS ADCs: 8.5mdB
- Minimum gain: −1.16dB
- Maximum gain: 38.8dB
- −3dB bandwidth (BW): 900MHz
- Rise and fall time: < 500ps
- Recovery time: < 5ns
- Propagation delay variation: 100ps
- HD2 at 100MHz: −50dBc
- HD3 at 100MHz: −53dBc
- Input-referred noise (maximum gain): 0.98nV/√Hz
- Overvoltage clamps for fast recovery
- Power consumption: auxiliary turned off 1.1W to 0.75W
The LMH6518 is a digitally controlled variable gain amplifier with a total gain that varies from –1.16dB to 38.8dB for a 40dB range in 2dB steps. The −3dB bandwidth is 900MHz at all gains. Gain accuracy at each setting is typically 0.1dB. When used in conjunction with TI’s gigasamples per second (GSPS) ADC with adjustable full-scale range, the LMH6518 gain adjustment accommodates full scale input signals from 6.8mVPP to 920mVPP to get 700mVPP nominal at the ADC input. The auxiliary output (+OUT AUX and −OUT AUX) follows the main output and is intended for use in oscilloscope trigger function circuitry, but can have other uses in other applications.
The LMH6518 gain is programmed through a SPI-compatible serial bus. A signal path combined gain resolution of 8.5mdB is achieved when the device gain and the GSPS ADC FS input are both manipulated. Inputs and outputs are dc-coupled. The outputs are differential with individual common-mode voltage control (for main and auxiliary outputs), and have selectable bandwidth limiting circuitry (common to both main and auxiliary) of 20MHz, 100MHz, 200MHz, 350MHz, 650MHz, 750MHz, or full BW.
Technical documentation
| Type | Title | Date | ||
|---|---|---|---|---|
| * | Data sheet | LMH6518 900MHz, Digitally Controlled Variable Gain Amplifier datasheet (Rev. E) | PDF | HTML | 31 Jul 2024 |
| EVM User's guide | LMH6518 Evaluation Module User's Guide | PDF | HTML | 08 Oct 2024 | |
| E-book | The Signal e-book: A compendium of blog posts on op amp design topics | 28 Mar 2017 | ||
| Application note | AN-1718 Differential Amplifier Applications Up to 400 MHz (Rev. B) | 01 May 2013 | ||
| Application note | AN-1719 Noise Figure Analysis Fully Differential Amplifier (Rev. A) | 01 May 2013 | ||
| EVM User's guide | AN-1906 LMH6518 Evaluation Board (Rev. B) | 01 May 2013 | ||
| Application note | Using High Speed Diff Amp to Drive ADCs (Rev. A) | 26 Apr 2013 | ||
| More literature | Featured High Speed Differential Amplifiers | 23 Oct 2012 | ||
| Application note | A Walk Along the Signal Path (High-Speed Signal Path) | 30 Mar 2005 |
Design & development
For additional terms or required resources, click any title below to view the detail page where available.
LMH6518EVM — LMH6518 evaluation module
LMH6518DESIGN-CALC — LMH6518 Application Information FS Gain ECM Calculator
PSPICE-FOR-TI — PSpice® for TI design and simulation tool
TINA-TI — SPICE-based analog simulation program
| Package | Pins | CAD symbols, footprints & 3D models |
|---|---|---|
| WQFN (RGH) | 16 | Ultra Librarian |
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