Imaging

The ADAS1134 is a 128-channel, current-to-digital, analog-to-digital converter (ADC). It contains 128 low power, low noise, low input current integrators, simultaneous sample-and-holds, and two high speed, high resolution ADCs with configurable sampling rate and resolutions up to 24 bits.

All converted channel results are output on a single, low voltage differential signaling (LVDS), self clocked serial interface, which reduces external hardware.

An SPI-compatible serial interface allows configuration of the ADC using the SDI input. The SDO output allows the user to daisy-chain several ADCs on a single, 3-wire bus. The ADAS1134 uses IOVDD, a separate supply, to reduce digital noise effect on the conversions.

The ADAS1134 is available in a 10 mm × 10 mm, 242-ball CSP_BGA package.

Applications

• Medical, industrial, and security CT scanner data acquisition
• Photodiode sensors
• Dosimetry and radiation therapy systems
• Optical fiber power monitoring
• X-ray detection systems
• High channel count data acquisition systems (current or voltage inputs)

All converted channel results are output on a single, low voltage differential signaling (LVDS), self clocked serial interface, which reduces external hardware.

An SPI-compatible serial interface allows configuration of the ADC using the SDI_x input. The SDO_x output allows the user to daisy-chain several ADCs on a single, 3-wire bus. The ADAS1131 uses the separate supply, IOVDD, to reduce digital noise effect on the conversions.

The ADAS1131 is in a 15 mm × 15 mm, CSP_BGA package.

APPLICATIONS

• Medical, industrial, and security CT scanner data acquisition
• Photodiode sensors
• Dosimetry and radiation therapy systems
• Optical fiber power monitoring
• X-ray detection systems
• High channel-count data acquisition systems (current or
  voltage inputs)

The ADAS1256 is a 256-channel, charge-to-digital analog-front end (AFE) mounted on high density flex. It can be directly mounted on a digital X-ray panel. It is suitable for a large variety of digital X-ray and photodiode array applications and it works with both hole sensing and electron sensing panels. ADAS1256 allows up to 22us line time, so it can be used in dynamic imaging panels in addition to still image panels. It contains 256 low power, low noise, low input current integrators with correlated double sampling stages; along with integrated true 16 bit high speed ADCs.

All converted channel results are output on a single LVDS self-clocked serial interface that significantly reduces external hardware. An SPI-compatible serial interface allows configuration of the AFE using SDI input. The SDO output allows the user to daisy chain several AFEs on a single 3-wire bus.

An integrated AFE timing sequencer controls the sampling activity of the analog front end (AFE). The sequencer is programmed via the SPI port and is timed by a single clock, ACLK.

APPLICATIONS

• Digital X-ray panel
• Photodiode sensors array
• CT Scanner
• High channel count data acquisition systems (current or voltage input)
• TFT panel readout

The AD9271 is designed for low cost, low power, small size, and ease of use. It contains eight channels of a variable gain amplifier (VGA) with low noise preamplifier (LNA); an antialiasing filter (AAF); and a 12-bit, 10 MSPS to 50 MSPS analog-to-digital converter (ADC).

Each channel features a variable gain range of 30 dB, a fully differential signal path, an active input preamplifier termination, a maximum gain of up to 40 dB, and an ADC with a conversion rate of up to 50 MSPS. The channel is optimized for dynamic performance and low power in applications where a small package size is critical.

The LNA has a single-ended-to-differential gain that is selectable through the SPI. The LNA input noise is typically 1.2 nV/√Hz, and the combined input-referred noise of the entire channel is 1.4 nV/√Hz at maximum gain. Assuming a 15 MHz noise bandwidth (NBW) and a 15.6 dB LNA gain, the input SNR is roughly 86 dB. In CW Doppler mode, the LNA output drives a transconductance amp that is switched through an 8 × 6 differential crosspoint switch. The switch is programmable through the SPI.

APPLICATIONS

• Medical imaging/ultrasound
• Automotive radar

The circuit shown in Figure 1 demonstrates isolation of an analog front end (18-bit, 5 MSPS AD7960 analog-to-digital converter (ADC)) at 600 Mbps using the ADN4651 LVDS isolator. An interposer board with the ADN4651 connects to the standard AD7960 evaluation platform, isolating the analog front end board from the high speed SDP-H1 system demonstration platform (EVAL-SDP-CH1Z). The SDP-H1 contains a Xilinx Spartan 6 FPGA to capture acquisitions and a ADSP-BF527 DSP to communicate with the PC.

Galvanic isolation of external interfaces is required in harsh environments for safety, functionality, or improved noise immunity. This includes analog front ends used in data acquisition modules for industrial measurement and control. Bandwidth requirements for converter interfaces are increasing, as trends such as Industry 4.0 and the Internet of Things (IoT) demand far more ubiquitous measurement and control, with greater speed and precision. This poses a challenge for isolation, because even standard digital isolators are limited to 150 Mbps operation.

For measurement and control applications in industrial environments, the benefits of such an isolated analog front-end implementation include:

• Ease of design due to the drop-in LVDS isolator with fully compliant input/output and ultralow jitter.
• High bandwidth of 600 Mbps to support increased ADC resolution and speed.
• Galvanic isolation for protection from mains voltages, isolated measurement of power supplies, or noise immunity from digital or power supply circuits.

The circuit in Figure 1 demonstrates an industry-leading solution to LVDS isolation at 600 Mbps using the ADN4651 dual-channel isolator.

The circuit shown in Figure 1 is an 18-bit, 5 MSPS low power, low noise, high-precision complete data acquisition signal-chain solution that dissipates only 122 mW. The reference, reference buffer, driver amplifiers, and ADC provide an optimized solution with industry-leading SNR of 99 dB, THD of −117 dB. The circuit is ideal for portable applications because of its low power and small PCB footprint.

The circuit shown in Figure 1 provides a method to convert a high frequency single-ended input signal to a balanced differential signal used to drive the AD7626 16-bit, 10 MSPS PulSAR^® ADC. The circuit maximizes the AD7626 performance for high frequency input tones using the ADA4932-1 low power differential amplifier to drive the ADC. The true benefit of this combination of devices is high performance at low power.

The AD7626 industry breakthrough dynamic performance of 91.5 dB SNR at 10 MSPS with 16-bit INL performance, no latency, and LVDS interface, all coupled with power dissipation of only 136 mW. A key feature of the SAR architecture used in the AD7626 is the ability to sample at 10 MSPS without the latency, or "pipeline delay," typically incurred with pipeline ADCs coupled with the excellent linearity performance.

The ADA4932-1 has low distortion (100 dB SFDR @ 10 MHz), fast settling time (9 ns to 0.1%), high bandwidth (560 MHz, −3 dB, G = 1), and low current (9.6 mA). These characteristics make it the ideal choice for driving the AD7626. It also features the functionality to easily set the required output common- mode voltage.

The combination offers industry-leading dynamic performance and small board area with the AD7626 in a 5 mm × 5 mm, 32-lead LFCSP, the ADA4932-1 in a 3 mm × 3 mm, 16-lead LFCSP, and the AD8031 in a 5-lead SOT-23 package.

The circuit shown in Figure 1 is a cost effective, isolated, multi-channel data acquisition system that is compatible with standard industrial signal levels. The components are specifically selected to optimize settling time between samples, providing 18-bit performance at channel switching rates up to approximately 750 kHz.

The circuit can process eight gain-independent channels and is compatible with both single-ended and differential input signals.

The analog front end includes a multiplexer, programmable gain instrumentation amplifier (PGIA); precision analog-to-digital converter (ADC) driver for performing the single-ended to differential conversion; and an 18-bit, 2.0 MSPS precision PulSAR^® ADC for sampling the signal on the active channel. Gain configurations of 0.4, 0.8, 1.6, and 3.2 are available.

The maximum sample rate of the system is 2 MSPS in turbo mode, and 1.5 MSPS in normal mode. The channel switching logic is synchronous to the ADC conversions, and the maximum channel switching rate is 1.5 MHz. A single channel can be sampled at up to 2 MSPS with 18-bit resolution in turbo mode. Channel switching rates up to 750 kHz also provide 18-bit performance.

The circuit in Figure 1 is a two-channel, bank isolated, wide bandwidth data acquisition (DAQ) system, implemented with a simultaneous sampling architecture using an analog-to-digital converter (ADC) per channel. The system achieves high channel density along with isolation between the bank and the digital backplane, all while delivering exceptional performance. The design also makes efficient use of isolation channels by configuring the ADCs in daisy-chain mode and utilizing an isolator product with a trimmed delay clock feature. Power generation is also simplified using an isolator with an integrated pulse width modulation (PWM) controller and transformer driver to perform dc-to-dc conversion across the isolation barrier. The system also includes many common features of a typical DAQ signal chain, including input circuit protection, programmable gain channels, high accuracy, and high performance.

The simultaneous sampling realizes multiple channels without sample rate limitations inherent in multiplexed DAQ signal chains. The analog front end (AFE) design is also simpler than the multiplexed option, because the settling performance requirements of the system are less demanding. Sampling occurs simultaneously for each channel, while sequential sampling systems have delays between channels.

Digital bank isolated DAQ designs provide protection for digital back end circuitry and reduce ground loop and common-mode interference between banks. They feature multiple DAQ signal chains per ground plane, and can be implemented with fewer digital isolation devices than channel-to-channel isolated systems.

The circuit shown in Figure 1 is a cost effective, low power, multichannel data acquisition system that is compatible with standard industrial signal levels. The components are specifically selected to optimize settling time between samples, providing 18-bit performance at channel switching rates up to approximately 750 kHz.

The circuit can process eight gain-independent channels and is compatible with both single-ended and differential input signals.

The analog front end includes a multiplexer, programmable gain instrumentation amplifier (PGIA); precision analog-to-digital converter (ADC) driver for performing the single-ended to differential conversion; and an 18-bit, 1 MSPS PulSAR^® ADC for sampling the signal on the active channel. Gain configurations of 0.4, 0.8, 1.6, and 3.2 are available.

The maximum sample rate of the system is 1 MSPS. The channel switching logic is synchronous to the ADC conversions, and the maximum channel switching rate is 1 MHz. A single channel can be sampled at up to 1 MSPS with 18-bit resolution. Channel switching rates up to 750 kHz also provide 18-bit performance. The system also features low power consumption, consuming only 240 mW at the maximum ADC throughput rate of 1 MSPS.