Overview
The LMH6518SQ/NOPB, produced by Texas Instruments, is a digitally controlled variable gain amplifier designed for high-frequency applications. This device is optimized to drive TI's gigasample per second (GSPS) analog-to-digital converters (ADCs) with a 100-Ω input impedance and an 800 mVPP full-scale input voltage. The LMH6518 features a gain range of 40 dB, adjustable in 2 dB steps, and a combined gain resolution of 8.5 mdB when used with GSPS ADCs. It has a -3 dB bandwidth of 900 MHz across all gain settings, making it suitable for various high-frequency applications.
Key Specifications
| Parameter | Min | Typ | Max | Unit |
|---|---|---|---|---|
| Gain Range | -1.16 dB | - | 38.8 dB | dB |
| Gain Step Size | - | 2 dB | - | dB |
| -3 dB Bandwidth | - | 900 MHz | - | MHz |
| Rise Time | - | 460 ps | - | ps |
| Fall Time | - | 450 ps | - | ps |
| Recovery Time | - | < 5 ns | - | ns |
| Propagation Delay Variation | - | 100 ps | - | ps |
| Input-Referred Noise (Max Gain) | - | 0.98 nV/√Hz | - | nV/√Hz |
| Power Consumption (Auxiliary Off) | 0.75 W | - | 1.1 W | W |
| Package Type | - | 16-Pin WQFN | - | - |
Key Features
- Digitally controlled variable gain with a 40 dB range in 2 dB steps.
- -3 dB bandwidth of 900 MHz at all gains.
- Gain accuracy of ±0.1 dB at each setting.
- Combined gain resolution of 8.5 mdB with GSPS ADCs.
- Selectable bandwidth limiting circuitry (20 MHz, 100 MHz, 200 MHz, 350 MHz, 650 MHz, 750 MHz, or full bandwidth).
- Differential outputs with individual common-mode voltage control.
- Overvoltage clamps for fast recovery.
- Auxiliary output for oscilloscope trigger functions or other applications.
- Programmable via SPI-compatible serial bus.
Applications
- Oscilloscope programmable gain amplifiers.
- Differential ADC drivers.
- High-frequency single-ended input to differential conversion.
- Precision gain control applications.
- Medical applications.
- RF/IF applications.
Q & A
- What is the gain range of the LMH6518? The gain range is from -1.16 dB to 38.8 dB in 2 dB steps.
- What is the -3 dB bandwidth of the LMH6518? The -3 dB bandwidth is 900 MHz across all gain settings.
- How is the gain of the LMH6518 controlled? The gain is controlled via a SPI-compatible serial bus.
- What is the combined gain resolution when used with GSPS ADCs? The combined gain resolution is 8.5 mdB.
- What are the power consumption ranges for the LMH6518? The power consumption ranges from 0.75 W to 1.1 W with the auxiliary output turned off.
- What types of outputs does the LMH6518 have? The LMH6518 has differential outputs with individual common-mode voltage control and an auxiliary output.
- What is the purpose of the auxiliary output? The auxiliary output is intended for use in oscilloscope trigger functions but can be used in other applications as well.
- What is the package type of the LMH6518? The LMH6518 comes in a 16-Pin WQFN package.
- What are some of the key applications of the LMH6518? Key applications include oscilloscope programmable gain amplifiers, differential ADC drivers, high-frequency single-ended input to differential conversion, precision gain control, medical applications, and RF/IF applications.
- What is the input-referred noise at maximum gain? The input-referred noise at maximum gain is 0.98 nV/√Hz.
