The LMH6518 device is a digitally controlled variable gain amplifier whose total gain is
varied from −1.16 dB to 38.8 dB for a 40 dB range in 2-dB steps. The −3-dB bandwidth is 900 MHz at all
gains. Gain accuracy at each setting is typically 0.1 dB. When used in conjunction with TI's
Gsample/second (Gsps) ADC with adjustable full-scale (FS) range, the LMH6518 gain adjustment
accommodates full scale input signals from 6.8 mVPP to 920
mVPP to get 700 mVPP 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 may have other uses in other applications.
The LMH6518 gain is programmed through a SPI-1 compatible serial bus. A signal path
combined gain resolution of 8.5 mdB is achieved when the device's gain and the Gsps ADC’s FS input
are both manipulated. Inputs and outputs are DC-coupled. The outputs are differential with
individual common mode (CM) voltage control (for main and auxiliary outputs), and have a selectable
bandwidth limiting circuitry (common to both main and auxiliary) of 20, 100, 200, 350, 650, 750 MHz
or full bandwidth.
- Gain Range: 40 dB
- Gain Step Size: 2 dB
- Combined Gain Resolution With Gsps ADCs:
8.5 mdB - Minimum Gain: −1.16 dB
- Maximum Gain: 38.8 dB
- −3 dB BW: 900 MHz
- Rise and Fall Time: <500 ps
- Recovery Time: <5 ns
- Propagation Delay Variation: 100 ps
- HD2 at 100 MHz: −50 dBc
- HD3 at 100 MHz: −53 dBc
- Input-Referred Noise (Maximum Gain): 0.98 nV/√Hz
- Overvoltage Clamps for Fast Recovery
- Power Consumption: Auxiliary Turned Off 1.1 W to 0.75 W
| PGA/VGA | PGA |
| Number of channels | 1 |
| BW at Acl (MHz) | 900 |
| Vs (max) (V) | 5.25 |
| Vs (min) (V) | 4.75 |
| Acl, min spec gain (V/V) | 0.87 |
| Gain (max) (dB) | 38.8 |
| Architecture | Fully Differential ADC Driver |
| Slew rate (typ) (V/µs) | 760 |
| Operating temperature range (°C) | -40 to 85 |
| Features | Digital Gain Set, Integrated Clamps, Single-ended to Differential conversion |
| Rating | Catalog |