Data acquisition


the higher phase mismatch between channels, caused primarily by the analogue AAF. Without simultaneous sampling and phase calibration registers, the last resort to reduce phase mismatch errors is to calibrate them through timing. An FPGA can control the timing to start capturing data per channel, requiring high frequency clocks and phase/delay locked-loops. This adds much complexity to the DAQ solution.


THE WORLD OF µMODULE SOLUTIONS


µModule solutions provide phase matching solutions at the package level.


Integrating the complete signal chain into a


system-in-package (SIP) enables the µModule solution to provide a data sheet outlining the performance of the entire signal chain. While eliminating significant PCB assembly issues such as cold solders and bill-of-materials (BOM) availability, it has enhanced performance enabled by ADI’s integrated passives (iPassives) technology, allowing customers to solve complex system-level challenges, such as phase matching. ADI’s ADAQ7768-1 single-channel µModule


DAQ system suitable for CM applications includes a 36 V programmable gain instrumentation amplifier (PGIA), a fourth order active antialiasing filter (AAF), and a 24-bit DTSD ADC with the same features as the AD7768-1. Utilising an iPassives network for its fourth-order analogue AAF, the ADAQ7768-1 is able to achieve a tight device-to-device phase matching performance, comparable to simultaneous sampling ADCs and their phase calibration resolution, as seen in Table 2 and Figure 9. Figure 10 illustrates how an iPassives network achieves its close matching from fabrication, expressing the difference in resistance through the color gradients. iPassives resistor tolerance can go below 0.1%, while temperature coefficient of resistance (TCR) can be matched less than 1 ppm/°C, translating to a tightly controlled RC filter bandwidth that is stable across temperature. With


the use of iPassives network, µModule solutions solve the phase mismatch problem through the BOM and assembly approach, setting a new level of performance that is limited in traditional discrete signal chains.


Figure 4. Improper grounding in an accelerometer installation.


Figure 5. Proper grounding: Grounded at the instrumentation, isolated at the accelerometer.


TABLE 2. PHASE MATCHING PERFORMANCE AND PHASE CALIBRATION RESOLUTION ACROSS VARIOUS ADCS INCLUDING PRECISION SIGNAL CHAIN UMODULE SOLUTIONS


AD7768/ AD7768-4


Channel-to-channel phase matching at 20 kHz (max)*


Phase calibration resolution at 20 kHz


AD4134 ADAQ7768-1 ADAQ7767-1


0.024°


0.22°


0.20°


0.88°


*ADAQ776x-1 Phase Mismatch Max = 6 sigma (Typ = ±1 sigma) *Phase Matching = Phase Mismatch * 2


22 September 2024 Instrumentation Monthly


0.3°


Page 1  |  Page 2  |  Page 3  |  Page 4  |  Page 5  |  Page 6  |  Page 7  |  Page 8  |  Page 9  |  Page 10  |  Page 11  |  Page 12  |  Page 13  |  Page 14  |  Page 15  |  Page 16  |  Page 17  |  Page 18  |  Page 19  |  Page 20  |  Page 21  |  Page 22  |  Page 23  |  Page 24  |  Page 25  |  Page 26  |  Page 27  |  Page 28  |  Page 29  |  Page 30  |  Page 31  |  Page 32  |  Page 33  |  Page 34  |  Page 35  |  Page 36  |  Page 37  |  Page 38  |  Page 39  |  Page 40  |  Page 41  |  Page 42  |  Page 43  |  Page 44  |  Page 45  |  Page 46  |  Page 47  |  Page 48  |  Page 49  |  Page 50  |  Page 51  |  Page 52  |  Page 53  |  Page 54  |  Page 55  |  Page 56  |  Page 57  |  Page 58  |  Page 59  |  Page 60  |  Page 61  |  Page 62  |  Page 63  |  Page 64  |  Page 65  |  Page 66  |  Page 67  |  Page 68  |  Page 69  |  Page 70  |  Page 71  |  Page 72  |  Page 73  |  Page 74  |  Page 75  |  Page 76  |  Page 77  |  Page 78  |  Page 79  |  Page 80  |  Page 81  |  Page 82  |  Page 83  |  Page 84  |  Page 85  |  Page 86  |  Page 87  |  Page 88  |  Page 89  |  Page 90  |  Page 91  |  Page 92  |  Page 93  |  Page 94  |  Page 95  |  Page 96  |  Page 97  |  Page 98  |  Page 99  |  Page 100