The AD1974 is a high performance, single-chip ADCthat provides four analog-to-digital converters (ADCs) with differential inputs using the Analog Devices, Inc. patented multibit sigmadelta (?-?) architecture.An SPI port is included, allowing a microcontroller to enable mutes and adjust many other parameters. The AD1974 operates from 3.3 V digital and analog supplies. The AD1974 is available in a single-ended output 48-lead LQFP. The AD1974 is designed for low EMI. This consideration is apparent in both the system and circuit design architectures. By using the on-board phase-locked loop (PLL)to derive the master clock from the LR clock or from an external crystal, the AD1974 eliminates the need for a separate high frequency master clock and can also be used with a suppressed bit clock. The ADCs are designed using the latest continuous time architectures from Analog Devices to further minimize EMI. By using 3.3 V supplies, power consumption is minimized, further reducing emissions.