A 13bit 2.2MSample/s 55mW CMOS Modulator

Figure 1: Die microphotograph

Figure 2: 4th-order 2-1-1 cascade multi-bit M

a) Schematic

b) Digital blocks and coefficient relations

Figure 3: Fully-differential SC schematic (analog part)

Figure 4: Fully-differential folded-cascode OTA and dynamic CMFB net

Figure 5: Fully-differential 3-bit A/D and D/A converter

Figure 6: Measurements

a) Two-layer PCB used for testing	b) Measured output spectrum
c) Comparison of the different order noise shaping: Output spectrum for no input signal of the first-stage (blue), first- and second-stage combined (red), and complete modulator.
d) In-band (DC-1.1MHz) signal-to-(noise + distortion) ratio as a function of the input amplitude. Detail of the large-input range measured from 20 samples