AD8264 - Quad, 235 MHz, DC Coupled VGA
AD8264 - Quad, 235 MHz, DC Coupled VGA
The AD8264 is a four-channel linear-in-dB, general-purpose Variable Gain Amplifier intended for use in a broad range of applications, from medical imaging to communications, at frequencies from DC to 80 MHz (large signal). It is an integrated, high performance solution, with each channel comprising of a high-impedance input preamplifier, a single-ended high-speed VGA output with a -3dB bandwidth of 235 MHz, and a separate differential amplifier output to 80 MHz.
Dual supply operation enables gain control of negative-going pulses such as generated by photodiodes, photo-multiplier tubes, and video signals. DC coupling and large bandwidth make this amplifier a very good pulse processor. The differential output amplifier allows for easy level shift and interfacing to ADC’s via the VOCM and OFSx pins.
The VGA has 24 dB of gain range. The gain control interface provides a precise linear-in-dB scale of 20 dB/V where VGAIN is defined as VGNHx minus VGNLO. The differential gain control allows for easy interface to a variety of external analog and digital circuits. One common GNLO pin for all channels is provided to adjust the common-mode of the gain control input. Each channel has independent gain control.
Features
- Low Noise:
- Voltage noise = 2.3 nV/√Hz
- Current noise = 5 pA/√Hz
- Wide Bandwidth: Small Signal: 235 MHz (VGAx); 80 MHz (Diff. Amp Out)
- Large Signal: 80 MHz (1Vp-p) - Gain Range:
- 0 to +24 dB (SE-In to VGAx)
- +6 to +30 dB (SE-In to Diff-Out)
- 0 to +24 dB (SE-In to SE-Out) - Gain scaling: 20 dB/V
- DC coupled
- Single ended input and differential output
- Supplies: ±2.5...±5 V
- Low power: 125 mW per channel @ ±3.3 V
Key Applications
- Multi-Channel data acquisition
- Positron emission tomography
- Gain trim
- Industrial and medical ultrasound
- Radar receivers
