Analog Devices is offering a 24-bit Quad-Channel ADC, the AD7134, a low noise, precision type, simultaneous sampling Analog to Digital Converter that while offering exceptional functionality and performance, is also easy to use.
The AD7134 operates on the continuous-time sigma-delta or CTSD modulation scheme. This helps to remove the traditional requirement of a sampling switched capacitor circuitry preceding the sigma-delta modulator—simplifying the input driving requirement for the ADC. The device also has inherent antialiasing capability, arising out of the CTSD architecture rejecting signals around the aliasing frequency band of the ADC. Therefore, this ADC does not need the regular complex antialiasing filter.
The four independent converter channels of the AD7134 operate in parallel, and each of them has its own CTSD modulator along with a digital filtering and decimation path. Therefore, the user can sample four separate analog signals, each with a maximum input bandwidth of 391.5 kHz. The four signal measurements can also achieve tight phase matching among themselves. Therefore, the AD7134 can offer a high density of multichannel data acquisition in a small form factor, because of its simplified requirement of analog front-end, and a high level of channel integration.
ADCs normally require a complicated signal chain and an analog front-end circuitry that introduces distortion, mismatch, error, and noise at the ADC output. As the AD7134 simplifies the signal chain requirements, it also improves the system level performance of the device.
Offering excellent AC and DC performance, the bandwidth for each ADC channel of the device ranges from 0 to 391.5 kHz. Therefore, the AD7134 is an ideal choice for acquiring data with universal precision, and capable of supporting a variety of sensor types ranging from shock and vibration to pressure and temperature.
With several configuration options and features, the AD7134 offers the user the flexibility of achieving an optimal balance between power, accuracy, noise, and bandwidth for specific applications.
Analog Devices has integrated an asynchronous sample rate converter or ASRC with their AD7134 for precise control of the decimation ratio. This, in turn, allows the AD7134 to support a wide range of output data rates or ODR frequencies ranging from 0.01 kSPS to 1496 kSPS as the ODR uses interpolation and resampling techniques. Furthermore, as the adjustment resolution between the ODRs is less than 0.01 SPS, the user can vary the sampling speed granularly to achieve coherent sampling.
The user can also use multiple AD7134 devices with synchronous sampling between them using a single system clock, and this is because of the ASRC slave mode operation. The slave mode simplifies the requirement of clock distribution for a data acquisition system of medium bandwidth as each ADC no longer requires routing of low jitter, high-frequency master clock from the digital back end.
The AD1734 can perform on-board averaging between two or four of its input channels. This results in improving the dynamic range while the device maintains its bandwidth. Combining two channels improves the results by about 3 dB, while combining all the four channels offers an improvement of nearly 6 dB.