IMPROVED NULL CANCELLATION IN A 6^th-ORDER Σ-Δ MODULATOR REALIZED WITH TWO 3^rd-ORDER SECTIONS

• Abstract:

  This paper presents an improved rnethod to digitally correct for statit, analog circuit imnperfections in a two-stage, 6^th order, cascaded (6-3) sigma-delta modulator. By adding a digital correction term to the output of die digital noise cancellation filter, the first stage parasitic quantization noise due to finite amplifier gain and C-Ratio mismatches can be completely removed. A 6-3 modulator implemented as a fully differential switched-capacitor circuit, designed for an OSR of 16, has heen fabricated in a 1.2 µm double-poly n-well CMOS process. Improvements have been made in the null cancellation leading to approximately a 10 dB increase in SNDR ovor a range of signal amplitudes from 12 µVolts to 500 mV. A peak SNDR/SFDR of 87/100 dB for a 1 MHz sample rate and 84/93 dB for a 2.5 MHz sample rate have heen achieved.
• Download:

  IMEKO-TC4-2002-044.pdf
• DOI:

  _unreg_tc4-2002.044

Event details:

• IMEKO TC:

  TC4
• Event name:

  TC4 Conference and Workshop 2002
• Title:

  4th International Conference on Advanced A/D and D/A Conversion Techniques and their Applications (together with 7th IMEKO TC4 Workshop on ADC Modelling and Testing)
• Place:

  Prague, CZECH REPUBLIC
• Time:

  26 June 2002 - 28 June 2002