Simulating the ADAQ4003 µModule Data Acquisition Solution in LTspice

ADAQ4003 is an 18-Bit, 2 MSPS, Precision Medium Bandwidth µModule Data Acquisition Signal Chain Solution that reduces development cycle of a precision measurement system by transferring the signal chain design challenge of component selection, optimization, and layout from the designer to the device. This device uses system-in-package technology that reduces end system component count by combining multiple common signal processing and conditioning blocks into a single device. These blocks include a high resolution 18-bit, 2 MSPS successive approximation register (SAR), analog-to-digital converter (ADC), a low noise, fully differential ADC driver amplifier (FDA), and a stable reference buffer. Crucial passive components are also incorporated into the single package resulting in a small form factor without sacrificing performance.


The LTspice Model

The ADAQ4003 model outfitted with voltage rails and input signals is already available as the LTspice macromodel’s example circuit. To quickly test this: press the component button within the software, search for ADAQ4003, then press the macromodel’s example button.

Figure1. ADAQ4003 LTspice macromodel


ADAQ4003 Simulation Results

Transient Simulation

In this transient analysis simulation example, the input connection on the ADAQ4003 is set to have a gain of 0.454 at the output of the internal FDA. Like the actual device, the user can probe the voltage levels at the ADAQ4003 LTspice model input and internal ADC input (FDA output). Referring to the plot below, the model exhibits the FDA gain and ADC quantization.

.tran 20u

Figure 2. ADAQ4003 Transient analysis simulation

AC Bandwidth Simulation

The bandwidth of the ADAQ4003 µModule Data Acquisition device is the frequency at which the converted output is 3dB down compared to converted output on the lower frequencies.

.ac dec 100 100 1G

Figure 3. ADAQ4003 AC Bandwidth simulation

Noise Density Simulation

The ADC noise is also considered in this LTspice model. The figure below shows the simulation results of the LTspice model’s noise spectral density and the total RMS noise.

.noise V(Vout) V1 dec 500 1 10Meg 

Figure 4. ADAQ4003 Noise density simulation


Check out the ADAQ4003 LTspice model for a complete simulation and go to the ADAQ4003 product page to learn more about this 18-Bit, 2 MSPS, μModule Data Acquisition Solution.

Simulation results can also be checked against the EVAL-ADAQ4003 Evaluation Board, already available for ordering.

To download LTspice software click on this link.