Overview
The AD604AR, produced by Analog Devices Inc., is an ultralow noise, very accurate, dual-channel, linear-in-dB variable gain amplifier (VGA). It is optimized for time-based variable gain control, particularly in ultrasound applications, but it also supports any application requiring low noise, wide bandwidth, and variable gain control. Each channel of the AD604AR features a high-performance preamplifier with an input-referred noise voltage of 0.8 nV/√Hz and a 300 kΩ input resistance. The amplifier uses a differential input exponential amplifier (DSX-AMP) architecture, which includes a variable attenuator and a high-speed fixed-gain amplifier, ensuring a very accurate linear-in-dB response.
Key Specifications
| Parameter | Value | Unit |
|---|---|---|
| Gain Range per Channel | 0 dB to 48 dB (preamp gain = 14 dB), 6 dB to 54 dB (preamp gain = 20 dB) | dB |
| Gain Scaling Factor | 20 dB/V to 40 dB/V | dB/V |
| Input Resistance | 300 kΩ | Ω |
| Bandwidth | 40 MHz (–3 dB) | MHz |
| Input Noise Voltage | 0.8 nV/√Hz | nV/√Hz |
| Supply Voltage | ±5 V | V |
| Power Dissipation | 220 mW (one complete channel), 95 mW (one DSX only) | mW |
| Operating Temperature Range | −40°C to +85°C | °C |
| Response Time | 0.6 μs (power-up), 0.4 μs (power-down) | μs |
Key Features
- Ultralow input noise at maximum gain
- Very accurate linear-in-dB response
- Dual-channel operation with independent gain control
- Variable gain scaling from 20 dB/V to 40 dB/V
- Stable gain with temperature and supply variations
- Single-ended unipolar gain control
- Power shutdown at the lower end of the gain control range
- Ability to drive ADCs directly
- High-performance preamplifier with access to its output for external filtering
Applications
- Ultrasound and sonar time-gain control
- High-performance Automatic Gain Control (AGC) systems
- Signal measurement applications
- Medical ultrasound systems, such as driving the AD9050, a 10-Bit, 40 MSPS ADC
Q & A
- What is the primary application of the AD604AR?
The AD604AR is primarily optimized for time-based variable gain control in ultrasound applications, but it can be used in any application requiring low noise, wide bandwidth, and variable gain control.
- What is the input-referred noise voltage of the AD604AR?
The input-referred noise voltage of the AD604AR is 0.8 nV/√Hz.
- What is the gain range per channel of the AD604AR?
The gain range per channel is 0 dB to 48 dB (with preamplifier gain of 14 dB) and 6 dB to 54 dB (with preamplifier gain of 20 dB).
- What is the bandwidth of the AD604AR?
The bandwidth of the AD604AR is 40 MHz (–3 dB).
- How does the gain scaling work on the AD604AR?
The gain scales linearly in decibels with control voltages from 0.4 V to 2.4 V, with a scaling factor of 20 dB/V to 40 dB/V.
- Can the AD604AR drive ADCs directly?
- What is the operating temperature range of the AD604AR?
The operating temperature range is −40°C to +85°C.
- How much power does the AD604AR dissipate?
The power dissipation is 220 mW for one complete channel and 95 mW for one DSX only.
- What is the response time of the AD604AR?
The power-up response time is 0.6 μs, and the power-down response time is 0.4 μs.
- Can the channels of the AD604AR be cascaded?
- What packages is the AD604AR available in?
The AD604AR is available in 24-lead SSOP, SOIC, and PDIP packages.
