Electronic Design

Broadband Filter/ADC Driver Family Sports High Accuracy

A family of five single and dual low-pass active filter/analog-to-digital converter (ADC) driver amplifier devices from Linear Technology Corp. provides high performance and wide bandwidths. The ICs offer the smallest form factor for filtering applications in broadband wireless communications and signal processing equipment, according to the company.

The LTC6603 dual, programmable 2.5-MHz filter/ADC driver features a dual matched programmable ninth-order switched-capacitor linear-phase filter and ADC driver. A serial peripheral interface (SPI) port allows adjustment of the low-pass cutoff frequency up to 2.5 MHz and its gain, or those specifications can be fixed by pin-strapping. The device’s programmability, sharp filter rolloff frequency response, and guaranteed phase and gain performance suit it well as a baseband filter for I/Q demodulators. The device comes in a 4- by 4-mm, 24-lead quad flat no-lead (QFN) package and starts at $7.50 each in 1000-piece quantities.

The LTC6601-1 is a low-noise 0.5% tolerance low-pass active filter and ADC driver with configurable bandwidth from 5 MHz to 28 MHz. The filter has a second-order linear-phase Butterworth response. It also has differential inputs and outputs. The filter’s on-chip resistors and capacitors that form its cutoff frequency, Q, and gain are laser trimmed at the factory to an absolute tolerance of 0.5% typical. These resistors and capacitors are pinned out, allowing users to pin-strap wide combinations of filter response and gain. The LTC6601-1 comes in a 4- by 4-mm, 20-lead QFN package and starts at $3.95 each in quantities of 1000.

The LTC6605-7, -10, and -14 are fixed-frequency, second-order, linear-phase, dual matched low-pass active filters with bandwidths of 7, 10, and 14, respectively. Each filter pair is tested and guaranteed to offer tight matching of phase and gain characteristics. These devices are well-suited for I/Q demodulator channel filtering in WiMAX and broadband wireless access equipment including point-to-point microwave links. The LTC6605 filters come in 6- by 3-mm, 22-lead DFN packages, with prices starting at $6.95 each in quantities of 1000.

All the filters are available in C grade specified for 0°C to 70°C and I-grade specified for –40°C to 85°C operation. All products are available immediately from stock.

Linear Technology


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