switched capacitor circuits in wireless communication
SWITCHED-CAPACITOR circuits play a critical role in analog/digital interfaces particularly highly integrated applications. In these applications, a complex, digital-signal-processing core is often interfaced to real-world inputs and outputs. Such applications include voice-band modems, disk drive read channels, set-top cable television receivers, base-band processing in wireless transceivers, and others. For these high-volume, dedicated applications, cost is often the most important factor. Increasing levels of mixed-signal integration have been instrumental in lowering the fabrication, packaging, and testing costs of these products. CMOS has proven to be the most cost-effective technology for achieving high levels of integration. For analog circuits this technology typically does not have the same raw performance as bipolar or Bi-CMOS, but for complex, mixed-signal applications CMOS offers a distinct cost advantage, as evidenced by the wide commercial acceptance of CMOS for analog signal processing. In particular, switched-capacitor circuits exploit the charge storing abilities of CMOS to achieve precision signal processing. Thus, high-performance filters and data converters can be implemented in CMOS. Although an increasing amount of signal processing is performed in the digital domain, the analog-digital interface will remain a fundamentally necessary element.