AFE5816 - Fully-Integrated, 16-Channel Ultrasound Analog Front-End With Passive CW Mixer, 0.95nV/rtHz

The AFE5816 is a highly-integrated, analog front-end (AFE) solution specifically designedfor ultrasound systems where high performance, low power, and small size are required.

The AFE5816 is an integrated analog front-end (AFE) optimized for medical ultrasoundapplication. The AFE5816 is a multichip module (MCM) device with two dies: VCA and ADC_CONV. Eachdie has total of 16 channels.

Each channel in the VCA die can be configured in two modes: time gain compensation (TGC)mode and continuous wave (CW) mode. In TGC mode, each channel includes an input attenuator (ATTEN),a low-noise amplifier (LNA) with variable-gain, and a third-order, low-pass filter (LPF). Theattenuator supports an attenuation range of 8 dB to 0 dB, and the LNA supports gain ranges from 14dB to 45 dB. The LPF cutoff frequency can be configured at 10 MHz, 15 MHz, 20 MHz, or 25 MHz tosupport ultrasound applications with different frequencies. In CW mode, each channel includes anLNA with a fixed gain of 18 dB, and a low-power passive mixer with 16 selectable phase delays.Different phase delays can be applied to each analog input signal to perform an on-chip beamformingoperation. A harmonic filter in the CW mixer suppresses the third and fifth harmonic to enhance thesensitivity of the CW Doppler measurement. CW mode supports three clock modes: 16X, 8X, and4X.

Each channel of the ADC_CONV die has a high-performance analog-to-digital converter (ADC)with a programmable resolution of 14 bits or 12 bits. The ADC achieves 75-dBFS signal-to-noiseratio (SNR) in 14-bit mode, and 72-dBFS SNR in 12-bit mode. This ADC provides excellent SNR atlow-channel gain. The devices operate at maximum speeds of 65 MSPS and 80 MSPS, providing 14-bitand 12-bit output, respectively. The ADC is designed to scale power with sampling rate. The outputinterface of the ADC is a low-voltage differential signaling (LVDS) interface that can easilyinterface with low-cost field-programmable gate arrays (FPGAs).

The AFE5816 also allows various power and noise combinations to be selected foroptimizing system performance. Therefore, these devices are suitable ultrasound AFE solutions forsystems with strict battery-life requirements. The AFE5816 is available in a 15-mm × 15-mmNFBGA-289 package (ZAV package, S-PBGA-N289) and is specified for operation from –40°C to +85°C.The device is also pin-to-pin compatible with the AFE5818 family.

• 16-Channel, AFE for Ultrasound Applications:
  • Input Attenuator, LNA, LPF, ADC, and
    CW Mixer
  • Optimized Signal Chains for TGC and CW Modes
  • Digital Time Gain Compensation (DTGC)
  • Total Gain Range: 6 dB to 45 dB
  • Linear Input Range: 1 V_PP
• Input Attenuator With DTGC:
  • 8-dB to 0-dB Attenuation with 0.125-dB Step
  • Supports Matched Impedance for:
    • 50-Ω to 800-Ω Source Impedance
• Low-Noise Amplifier (LNA) With DTGC:
  • 14-dB to 45-dB Gain with 0.125-dB Step
  • Low Input Current Noise: 1.2 pA/√Hz
• 3rd-Order, Linear-Phase, Low-Pass Filter (LPF):
  • 10 MHz, 15 MHz, 20 MHz, and 25 MHz
• Analog-to-Digital Converter (ADC) With Programmable Resolution:
  • 14-Bit ADC: 75-dBFS Idle Channel SNR at
    65 MSPS
  • 12-Bit ADC: 72-dBFS Idle Channel SNR at
    80 MSPS
• LVDS Interface With a Maximum Speed Up to
  1 GBPS
• Optimized for Noise and Power:
  • 90 mW/Ch at 1 nV/√Hz, 65 MSPS, TGC Mode
  • 55 mW/Ch at 1.45 nV/√Hz, 40 MSPS,
    TGC Mode
  • 59 mW/Ch, CW Mode
• Excellent Device-to-Device Gain Matching:
  • ±0.5 dB (Typical)
• Low Harmonic Distortion: –60-dBc Level
• Fast and Consistent Overload Recovery
• Continuous Wave (CW) Path with:
  • Passive Mixer
  • Low Close-In Phase Noise of –148 dBc/Hz
    at 1-kHz frequency
  • Phase Resolution: λ / 16
  • Supports 16X, 8X, 4X, and 1X CW Clocks
  • 12-dB Suppression of 3rd and 5th Harmonics
• Small Package: 15-mm × 15-mm NFBGA-289

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