24-Bit, 625 kSPS, 109 dB Sigma-Delta ADC with On-Chip Buffers, Serial Interface

The AD7763 high performance, 24-bit, Σ-Δ analog-to-digital converter (ADC) combines wide input bandwidth and high speed with the benefits of Σ-Δ conversion, as well as performance of 107 dB SNR at 625 kSPS, making it ideal for high speed data acquisition. A wide dynamic range, combined with significantly reduced antialiasing requirements, simplifies the design process. An integrated buffer to drive the reference, a differential amplifier for signal buffering and level shifting, an overrange flag, internal gain and offset registers, and a low-pass, digital FIR filter make the AD7763 a compact, highly integrated data acquisition device requiring minimal peripheral component selection. In addition, the device offers programmable decimation rates and a digital FIR filter, which can be user-programmed to ensure that its characteristics are tailored for the user’s application. The AD7763 is ideal for applications demanding high SNR without necessitating the design of complex, front-end signal processing.

The differential input is sampled at up to 40 MSPS by an analog modulator. The modulator output is processed by a series of low-pass filters, the final filter having default or user-programmable coefficients. The sample rate, filter corner frequencies, and output word rate are set by a combination of the external clock frequency and the configuration registers of the AD7763.

The reference voltage supplied to the AD7763 determines the analog input range. With a 4 V reference, the analog input range is ±3.2 V differential-biased around a common mode of 2 V. This common-mode biasing can be achieved using the on-chip differential amplifiers, further reducing the external signal conditioning requirements.

The AD7763 is available in an exposed paddle, 64-lead TQFPEP and is specified over the industrial temperature range from −40°C to +85°C.

APPLICATIONS

* Data acquisition systems

* Vibration analysis

* Instrumentation

* 120 dB dynamic range at 78 kHz output data rate

* 109 dB dynamic range at 625 kHz output data rate

* 112 dB SNR at 78 kHz output data rate

* 107 dB SNR at 625 kHz output data rate