- Adjustable Gain with a 31 dB Range
- Precise 1 dB Gain Steps
- Parallel 5-bit Gain Control
- On Chip Register Stores Gain Setting
- Fully Differential Signal Path
- Single Ended to Differential Capable
- 200? Input Impedance
- Small Footprint (4 mm x 4 mm) WQFN Package
Key Specifications
- 600 MHz bandwidth @ 100? load
- 40 dBm OIP3 @ 75 MHz, 200? load
- 20 dB to 30 dB maximum gain
- Selectable output impedance of 200? or 400?
- 8.3 dB noise figure
- 5 ns gain step switching time
- 100 mA supply current
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The LMH6515 is a high performance, digitally controlled variable gain amplifier (DVGA). It combines precision gain control with a low noise, ultra-linear, differential amplifier. Typically, the LMH6515 drives a high performance ADC in a broad range of mixed signal and digital communication applications such as mobile radio and cellular base stations where automatic gain control (AGC) is required to increase system dynamic range. When used in conjunction with a high speed ADC, system dynamic range can be extended by up to 32 dB.
The LMH6515 has a differential input and output allowing large signal swings on a single 5V supply. It is designed to accept signals from RF elements and maintain a terminated impedance environment. The input impedance is 200? resistive. The output impedance is either 200? or 400? and is user selectable. A unique internal architecture allows use with both single ended and differential input signals.
Input signals to the LMH6515 are scaled by a highly linear, digitally controlled attenuator with 31 accurate 1 dB steps. The attenuator output provides the input signal for a high gain, ultra linear differential transconductor. The transconductor differential output current can be converted into a voltage by using the on-chip 200? or 400? loads. The transconductance gain is 0.1 Amp/Volt resulting in a maximum voltage gain of +26 dB when driving a 200? load, or 32 dB when driving the 400? load. On chip digital latches are provided for local storage of the gain setting. The gain step settling time is 5 ns and care has been taken to reduce the sensitivity of bandwidth and phase to gain setting.
The LMH6515 operates over the industrial temperature range of ?40°C to +85°C. The LMH6515 is available in a 16-Pin, thermally enhanced, WQFN package.
