Overview
The AD604ARS, 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 AD604 provides a 300 kΩ input resistance and unipolar gain control for ease of use. The amplifier features a high-performance preamplifier with an input-referred noise voltage of 0.8 nV/√Hz and a differential input exponential amplifier (DSX-AMP) architecture.
Key Specifications
| Parameter | Conditions | Min | Typ | Max | Unit |
|---|---|---|---|---|---|
| Gain Scaling Factor | VREF = 2.5 V, 0.4 V < VGN < 2.4 V | 19 | 20 | 21 | dB/V |
| Gain Range | Preamp Gain = 14 dB | 0 | 48 | dB | |
| Gain Range | Preamp Gain = 20 dB | 6 | 54 | dB | |
| Input Voltage (VGN) Range | 20 dB/V, VREF = 2.5 V | 0.1 | 2.9 | V | |
| Input Resistance | 300 kΩ | ||||
| Response Time | 48 dB Gain Change | 0.2 | ms | ||
| Power Supply | One Complete Channel | ±5 V | |||
| Power Dissipation | One Complete Channel | 220 mW | |||
| Operating Temperature Range | −40°C | +85°C |
Key Features
- Ultralow input noise at maximum gain: 0.8 nV/√Hz
- Very accurate linear-in-dB response using differential input exponential amplifier (DSX-AMP) architecture
- Variable attenuator of 0 dB to 48.36 dB followed by a high-speed fixed-gain amplifier
- 7-stage R-1.5R ladder network attenuator
- Unipolar gain control with user-determined gain ranges and gain scaling (dB/V)
- DC level shifting of output
- Single-ended unipolar gain control
- Power shutdown at lower end of gain control
- Can drive ADCs directly
- Available in 24-lead SSOP, SOIC, and PDIP packages
Applications
- Ultrasound and sonar applications
- Time-gain control
- High-performance AGC (Automatic Gain Control) systems
- Signal measurement systems
- Any application requiring low noise, wide bandwidth, and variable gain control
Q & A
- What is the primary application of the AD604?
The AD604 is primarily optimized for time-based variable gain control in ultrasound applications.
- What is the input-referred noise voltage of the AD604?
The input-referred noise voltage of the AD604 is 0.8 nV/√Hz.
- What is the gain range of the AD604 per channel?
The gain range per channel is 0 dB through 48 dB and 6 dB through 54 dB, depending on the preamplifier gain setting.
- How does the gain control work on the AD604?
The gain control is unipolar and linear-in-dB, with control voltages of 0.4 V to 2.4 V for the 20 dB/V scale.
- What are the available packages for the AD604?
The AD604 is available in 24-lead SSOP, SOIC, and PDIP packages.
- What is the operating temperature range of the AD604?
The operating temperature range is −40°C to +85°C.
- Can the AD604 drive ADCs directly?
- How does the power shutdown feature work on the AD604?
The amplifier channel is powered down to 1.9 mA when the gain control voltage is less than 50 mV.
- What is the response time for a 48 dB gain change?
The response time for a 48 dB gain change is 0.2 ms.
- Can the channels of the AD604 be cascaded?
