SDAA114 September   2025 AMC0311D , AMC0311D-Q1 , AMC0311R , AMC0311R-Q1 , AMC0311S , AMC0311S-Q1 , AMC0330D , AMC0330D-Q1 , AMC0330R , AMC0330R-Q1 , AMC0330S , AMC0330S-Q1 , AMC0336 , AMC0380D , AMC0380D-Q1 , AMC0381D , AMC0381D-Q1 , AMC0381R-Q1 , AMC1211-Q1 , AMC1311 , AMC1311-Q1 , AMC1350 , AMC1350-Q1 , AMC1351 , AMC1351-Q1 , AMC1411 , AMC1411-Q1 , AMC3311 , AMC3311-Q1 , AMC3330 , AMC3330-Q1

 

  1.   1
  2.   Abstract
  3.   Trademarks
  4. 1Introduction
  5. 2Signal Chain
    1. 2.1 Inside the Multiplexed SAR ADC
    2. 2.2 Driving ADC With an Amplifier
  6. 3Experimental Results
    1. 3.1 DC Characteristics
    2. 3.2 AC Characteristics
  7. 4Summary
  8. 5References

3.2 AC Characteristics

The non-linearity in the DC transfer function transforms into harmonic distortion in the AC characteristics.

Figure 3-5, Figure 3-6, and Figure 3-7 show fast Fourier transform (FFT) of 8192 data samples. The effective sampling frequency is 312.5kHz, with a 16-bit resolution, and the sampling time remains unchanged from the DC discussion (tSMPL=425ns). The input signal (carrier) is a 10kHz sinewave with amplitude of 1V. The FFT uses Hanning window to suppress spectral leakage.

The negative effect we observe in the DC characteristic is visible in the AC domain as well. The TLV9001-based difference amplifier introduces unwanted harmonics as multiples of the carrier frequency. At least ten harmonics are visible before disappearing into the noise level. The systems with OPA365 or AMC0330S perform significantly better.

Output Spectrum of the Signal Chain With AMC0330D and TLV9001 Figure 3-8 Output Spectrum of the Signal Chain With AMC0330D and TLV9001
Output Spectrum of the Signal Chain With AMC0330D and OPA365 Figure 3-9 Output Spectrum of the Signal Chain With AMC0330D and OPA365
Output Spectrum of the Signal Chain with Single-Ended AMC0330S Figure 3-10 Output Spectrum of the Signal Chain with Single-Ended AMC0330S