AFE5808A - Fully-Integrated, 8-Channel Ultrasound Analog Front End With Passive CW Mixer

The AFE5808A is a highly-integrated, analog front-end (AFE) solution specifically designed for ultrasound systems in which high performance and small size are required. The AFE5808A integrates a complete time-gain-control (TGC) imaging path and a continuous wave Doppler (CWD) path. This device also enables users to select one of various power and noise combinations to optimize system performance. Therefore, the AFE5808A is an outstanding ultrasound analog front-end solution not only for high-end systems, but also for portable ones.

The AFE5808A device contains eight voltage controlled amplifiers (VCA), 14- and 12-bit analog-to-digital converters (ADC), and CW mixers. The VCA includes a low-noise amplifier (LNA), voltage-controlled attenuator (VCAT), programmable gain amplifier (PGA), and low-pass filter (LPF). The LNA gain is programmable to support 250 mV_PP to 1 V_PP input signals. Programmable active termination is also supported by the LNA. The ultralow noise VCAT provides an attenuation control range of 40 dB, and improves overall low gain SNR that benefits harmonic imaging and near field imaging. The PGA provides gain options of 24 dB and 30 dB. In front of the ADC, a LPF can be configured as 10 MHz, 15 MHz, 20 MHz, or 30 MHz to support ultrasound applications with different frequencies. The high-performance 14-bit, 65-MSPS ADC in the AFE5808A device achieves 77-dBFS SNR, and ensures excellent SNR at low-chain gain. The ADC LVDS outputs enable flexible system integration desired for miniaturized systems.

The AFE5808A device also incorporates a low-power passive mixer and a low-noise summing amplifier to accomplish on-chip CWD beamforming. Sixteen selectable phase-delays can be applied to each analog input signal. A unique 3rd- and 5th-order harmonic-suppression filter is implemented to enhance CW sensitivity.

The AFE5808A is available in a 15-mm × 9-mm, 135-pin BGA package and it is specified for operation from 0°C to 85°C. This device is also pin-to-pin compatible with the AFE5803, AFE5807, and AFE5808.

NOTE: The AFE5808A is an enhanced version of AFE5808 and is recommended for new designs. Compared to the AFE5808, the AFE5808A expands the cutoff frequency range of the digital high-pass filter; increases the handling capability of extreme overload signals; and lowers the correlated noise significantly when high-impedance source appears.

• 8-Channel Complete Analog Front-End
  • LNA, VCAT, PGA, LPF, ADC, and CW Mixer
• Programmable Gain Low-Noise Amplifier (LNA)
  • 24-, 18-, or 12-dB Gain
  • 0.25-, 0.5-, or 1-V_PP Linear Input Range
  • 0.63-, 0.7-, or 0.9-nV/√Hz Input-Referred Noise
  • Programmable Active Termination
• 40-dB, Low-Noise Voltage-Controlled Attenuator
  (VCAT)
• 24-, or 30-dB Programmable Gain Amplifier (PGA)
• 3rd-Order, Linear-Phase, Low-Pass Filter (LPF)
  • 10 MHz, 15 MHz, 20 MHz, or 30 MHz
• 14-bit Analog-to-Digital Converter (ADC)
  • 77-dBFS SNR at 65 MSPS
  • LVDS Outputs
• Noise and Power Optimizations (Full Chain)
  • 158 mW/CH at 0.75 nV/√Hz, 65 MSPS
  • 101 mW/CH at 1.1 nV/√Hz, 40 MSPS
  • 80 mW/CH in CW Mode
• Excellent Device-to-Device Gain Matching
  • ±0.5 dB (Typical) and ±0.9 dB (Maximum)
• Low Harmonic Distortion
• Fast and Consistent Overload Recovery
• Passive Mixer for Continuous Wave Doppler
  (CWD)
  • Low Close-in Phase Noise: –156 dBc/Hz at 1
    KHz Off 2.5-MHz Carrier
  • Phase Resolution of 1/16λ
  • Support 16X, 8X, 4X and 1X CW Clocks
  • 12-dB Suppression on 3rd and 5th Harmonics
  • Flexible Input Clocks
• Small Package: 15-mm × 9-mm, 135-Pin NFBGA