AFE5809

The AFE5809 device is a highly-integrated analog front-end (AFE) solution specifically designed for ultrasound systems in which high performance and small size are required. The AFE5809 device integrates a complete time-gain-control (TGC) imaging path and a CWD path. The device also enables users to select one of various power and noise combinations to optimize system performance. Therefore, the AFE5809 device is a suitable ultrasound AFE solution not only for high-end systems, but also for portable ones.

The AFE5809 device contains eight channels of voltage controlled amplifier (VCA), 14, and 12-bit ADC, and CW mixer. The VCA includes LNA, VCAT, PGA, and 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 ultra-low noise VCAT provides an attenuation control range of 40 dB and improves overall low-gain SNR, which benefits harmonic imaging and near-field imaging. The PGA provides gain options of 24 and 30 dB. Before the ADC, a LPF can be configured as 10, 15, 20, or 30 MHz to support ultrasound applications with different frequencies. In addition, the signal chain of the AFE5809 device can handle signal frequency lower than 100 kHz, which enables the device to be used in both sonar and medical applications. The high-performance 14-bit/65-MSPS ADC in the AFE5809 device achieves 77-dBFS SNR. It ensures excellent SNR at low chain gain. The ADC’s LVDS outputs enable flexible system integration desired for miniaturized systems.

The AFE5809 device integrates a low-power passive mixer and a low-noise summing amplifier to accomplish on-chip CWD beamformer. 16 selectable phase-delays can be applied to each analog input signal. Meanwhile, a unique third- and fifth-order harmonic suppression filter is implemented to enhance CW sensitivity.

The AFE5809 device also includes a digital in-phase and quadrature (I/Q) demodulator and a low-pass decimation filter. The main purpose of the demodulation block is to reduce the LVDS data rate and improve overall system power efficiency. The I/Q demodulator can accept ADC output with up to 65 MSPS sampling rate and 14-bit resolution. For example, after digital demodulation and 4× decimation filtering, the data rate for either in-phase or quadrature output is reduced to 16.25 MSPS and the data resolution is improved to 16 bits, consequently. Hence, the overall LVDS trace reduction can be a factor of 2. This demodulator can be bypassed and powered down completely if it is not needed.

The AFE5809 device is available in a 15-mm × 9-mm, 135-pin BGA package, and it is specified for operation from 0°C to 85°C.

Note: AFE5809 with date code later than 2014, that is date code >41XXXX, has below additional features which can be enabled by Register 61[15,14,13]. Existing analog performance remains the same.

• 61[13] enables an additional voltage clamp at the V2I input of the PGA. This limits the amount of overload signal the PGA sees.
• 61[14] enables a first-order 5-MHz LPF filter to suppress signals >5 MHz or high-order harmonics.
• 61[15] enables a –6-dB PGA clamp setting. The actual PGA output is less than the ADC’s full-scale amplitude, 2 Vpp.