Precision Signal Chain Design – How to manage the noise balance between multiple stages of the signal chain?

The LTC2387-18 is a low noise, high speed, 18-bit, 15Msps successive approximation register (SAR) ADC ideal for many applications. The LTC2387-18 combines excellent linearity and dynamic range, making it ideal for high-speed imaging and instrumentation applications. Latency-free operation provides a unique solution for high-speed control loop applications. Very low distortion at high input frequencies enables communication applications requiring wide dynamic range and large signal bandwidth.

Signal Chain Design

When designing a precision data acquisition measurement signal chain, one of the biggest challenges is managing the noise balance between the multiple stages of the signal chain:

• How much gain is required?
• Can the gain stage directly drive the analog-to-digital converter?
• Does digital filtering work?

With these questions in mind, ADI launched the “Precision Signal Chain Design – Trade-offs to achieve the best noise performance” online training course, this course will introduce from the sensor to the input of the analog-to-digital converter, in building an optimized signal conditioning solution challenges and trade-offs.

Typical Signal Chain Noise Spectrum Analysis

A typical signal chain generally consists of the sensor stage, gain stage, buffer stage and quantizer stage shown in the figure above. Noise exists in different stages. Generally, a filter is set at the gain stage to limit the noise bandwidth, while the noise of the buffer stage is Limited by the conversion rate of the ADC. In the noise spectral density plot, from left to right the sensor stage is excluded because it can be anywhere, the analog front end gain stage is shown in blue, the ADC noise spectral density is shown in orange, and the buffer stage noise spectral density is shown in green .

Practical Use Cases for the LTC2387-18

The LTC2387-18 is a low noise, high speed, 18-bit, 15Msps successive approximation register (SAR) ADC ideal for many applications. The LTC2387-18 combines excellent linearity and dynamic range, making it ideal for high-speed imaging and instrumentation applications. Latency-free operation provides a unique solution for high-speed control loop applications. Very low distortion at high input frequencies enables communication applications requiring wide dynamic range and large signal bandwidth.

digital filter help

The effect of digital filtering on noise is limited. Furthermore, due to hardware limitations making it difficult to achieve good filtering, there are some over-sampling-independent applications that may not gain the benefits of recently introduced sampling and filtering techniques. There may be power consumption implications, as well as slow processing and low output rates.

The Links:   FM50DY-10 6ES7-132-4BF00-0AA0