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Abstract-A low-distortion active filter is realized using currentefficient feedforward-compensated operational amplifiers in the integrators and feedforward current injection in the summing amplifier. A third-order elliptic low-pass filter with two possible bandwidth settings of 17 and 8.5 MHz consumes 1.8 mW from a 1.8-V supply and occupies 0.17 mm 2 in a 0.18-μm CMOS process. The measured maximum signal-to-noise and distortion ratios at the two bandwidth settings are 50.5 and 52.5 dB, respectively. The corresponding third-order intermodulation intercept points (IIP3) are +28.2 and +30.8 dBm. Automatic tuning is used at the startup to counter process variations and set the bandwidth accurately.

for a given network which caching architecture will produce the most economic benefit. This paper will investigate the many considerations and complex problems associated with optimizing caching designs that result in a low cost network. The location of caches and memory per cache, deploying hierarchical caching, and even methods to partition cache memory for multiple services are not easy problems.The benefit of caching depends on the cache effectiveness or hit rate-that is, the percentage of requests likely to be served from the cache. The popularity distribution of objects (e.g., channels or video titles) within a service governs which objects are most suitable for caching. Since popularity distributions will likely be different for each service, caching the same number of objects for two services will result in two different cache hit rates. The popularity of objects within a service is also a function of time-what is most popular today may not be as popular tomorrow-thus effective caching systems will need to measure the relative popularity of objects constantly. Nielsen* Media Research measures viewing behavior for

Caching of video content allows reduction of bandwidth and IPTV network cost. In this paper we introduce the concept of content cacheability and present a fast algorithm that uses cacheability to optimally partition a cache between several video services with different traffic characteristics and content sizes. The goal of the optimization is to serve maximum (in terms of bandwidth) amount of subscribers' requests subject to constraints on cache memory and throughput.

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