AFE5832LP - Low-power 32-ch ultrasound AFE with 18.5mW/ch power, LVDS interface, and passive CW mixer

The AFE5832LP is a highly integrated, analog front-end (AFE) solutionspecifically designed for portable ultrasound systems where high performance, low power, and smallsize are required.

The device is realized through a multichip module (MCM) with two dies: 1 VCA die and 1ADC die. The VCA die has 32 channels that interface with the 16 channels of the ADC die. Each ADCchannel alternately converts an odd and an even VCA channel.

Each channel in the VCA die can be configured in either of two modes:time-gain-compensation (TGC) mode or continuous wave (CW) mode. In the TGC mode, each channelincludes a low-noise amplifier (LNA), a programmable attenuator (ATTEN), a programmable gainamplifier and a third-order, low-pass filter (LPF). The LNA gain is programmable to 21 dB, 18 dB,or 15 dB. The ATTEN supports an attenuation range of 0 dB to 36 dB, with digital control for theattenuation. The PGA provides gain options from 21 dB to 27 dB in steps of 3 dB. The LPF cutofffrequency can be set between 10 MHz and 25 MHz to support ultrasound applications with differentfrequencies. In the CW mode, the output of the LNA goes to a low-power passive mixer with 16selectable phase delays. Different phase delays can be applied to each analog input signal toperform an on-chip beamforming operation. A harmonic filter in the CW mixer suppresses the thirdand fifth harmonic to enhance the sensitivity of the CW Doppler measurement.

The 16 channels of the ADC die can be configured to operate with a resolution of 12 bitsor 10 bits. The ADC resolution can be traded off with conversion rate and can operate at maximumspeeds of 80 MSPS and 100 MSPS at 12-bit and 10-bit resolution, respectively. Because each ADCalternately converts two VCA channels, the resulting maximum sample rate of each of the 32 channelsof the AFE is 40 MSPS and 50 MSPS in the 12-bit and 10-bit modes, respectively. The ADC is designedto scale its power with sampling rate. The output interface of the ADC comes out through alow-voltage differential signaling (LVDS), which can easily interface with low-costfield-programmable gate arrays (FPGAs).

A very low-power AFE solution makes it suitable for system with strict battery-liferequirement.

The AFE is available in a 15 mm × 15 mm 289-pin NFBGA package and is pin-compatible withthe AFE5832 family.

• 32-Channel AFE for Ultrasound Applications:
  • LNA, Attenuator, LPF, ADC, and CW Mixer
  • Digital Time Gain Compensation (DTGC)
  • Total Gain Range: 0 dB to 48 dB
• Low-Noise Amplifier (LNA) With Programmable Gain:
  • Low Current Noise of 1pA/rtHz
  • Gain: 21 dB, 18 dB, and 15 dB
  • Linear Input Range: up to 700 mV_PP
• Programmable Attenuator (ATTEN):
  • Attenuation Range (Steps of 0.125 dB):
    0 to 36 dB
  • Digital TGC Engine
• Programmable Gain Amplifier (PGA):
  • Gain: 21 dB, 24 dB, and 27 dB
• Third-Order, Linear-Phase, Low-Pass Filter (LPF):
  • Cut-off Frequency From 10 MHz to 25 MHz
• 16 ADCs Converting at 12-Bit, 80 MSPS or 10-Bit, 100 MSPS:
  • Each ADC Converts Two Sets of Inputs at Half Rate
  • 12-Bit Mode: 72-dBFS SNR
  • 10-Bit Mode: 61-dBFS SNR
• TGC Mode Power :
  • Lowest Power of 18.5 mW/Ch in Low Power Mode, 4 nV/rtHz, 10-Bit, 20 MSPS, LVDS (2x rate)
  • 27.8 mW/Ch at 3 nV/rtHz in Low Noise Mode at 12-Bit, 40 MSPS
  • 24.4 mW/Ch at 4 nV/rtHz in Low Power Mode at 12-Bit, 40 MSPS
• Excellent Device-to-Device Gain Matching:
  • ±0.5 dB (Typical)
• Harmonic Distortion: –55 dBc level
• Fast and Consistent Overload Recovery
• Continuous Wave (CW) Path With:
  • Low Close-In Phase Noise of –148 dBc/Hz at 1-kHz Frequency Offset off 5-MHz Carrier
  • Power Consumption With No Signal: 10 mW/Ch
  • Phase Resolution: λ/16
  • 12-dB Suppression on Third and Fifth Harmonics
• LVDS Interface with a Speed Up to 1-Gbps
• Small Package: 15-mm × 15-mm NFBGA-289

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