Synchronous demodulator with configurable analogue filter; analogue signal processing

October 30, 2014 // By Graham Prophet
Improving signal measurement sensitivity in low-power applications, ADI’s ADA2200 demodulator raises performance threshold for low-power signal processing applications, while reducing system complexity and board space.

ADI positions the synchronous demodulator as offering the optimum combination of integration, performance, flexibility and power consumption; the ADA2200 uses ADI's sampled analogue technology (SAT), developed at Lyric Semiconductor, (a company acquired by ADI in mid-2011), and incorporates a configurable analogue filter to enable designers of portable and low-power instrumentation to maximise battery life and perform precision magnitude and phase measurements on analogue signals in the presence of large noise sources.

Compared to traditional discrete implementations, this compact, integrated solution reduces PCB area by up to 25% and provides designers with a higher degree of flexibility, reducing system design and optimisation time and facilitating circuit design reuse across multiple sensors, products and platforms.

The low-power (390 µA at 3.3V and fCLK = 500 kHz) and rail-to-rail operation of the ADA2200 make it suitable for advanced battery-powered and low-voltage systems serving medical, industrial and communications markets and can be used in a wide variety of applications including impedance measurement, gas detection, air or fluid analysis, strain gauges and proximity measurement.

ADA2200 features a highly integrated analogue signal chain, including a configurable infinite impulse response (IIR) filter, low-pass finite impulse response (FIR) 1/8x decimation filter, mixer with 0°/90° phase selection, reference clock and A/D converter driver output. Optimised for input sampling rates up to 1 MHz, the ADA2200 enables demodulation of signal input bandwidths to 30 kHz, achieves 0.009º phase detection sensitivity and operates over a -40°C to +85°C temperature range.

ADI’s SAT technology uses charge-sharing among capacitors to perform “digital-like” computations in the analogue domain. By processing the signal entirely in the analogue domain, this analogue-in, sampled-analogue-out device reduces A/D converter sample rates, lowering A/D converter power consumption by up to 87% and offloads computationally heavy tasks from the digital processor or microcontroller. This allows designers to simplify their system architecture, shorten development time, and reduce system size and power consumption.

In a 16-lead TSSOP the device costs $2.95 (1000).