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Maxim >
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High-Frequency ASICs
RF and Wireless
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Circuit Design Examples
Maxim respects non-disclosure agreements with its ASIC customers.Due to the uniqueness and proprietary nature of ASICs, only a limited number of circuits are available for disclosure. The following examples demonstrate Maxim's expertise in development of wireless ASICs:
0.5 to 9GHz, +5V, 500mW, Dual Modulus Prescaler A broadband prescaler, capable of accomodating signalfrequencies from 0.5 to 9GHz, has been implemented on the GST-2 QuickChip 9-60D. Packaged in a 16-pin plastic dual-in-line package, the final ASIC is a low-cost, broadband solution for a variety of PLL systems. Please reference the following technical article for more information: Hughes Network Systems' Broadband PLL Building Block ASIC
GPS Receiver with Integrated Synthesizer The Symmetricom (www.symmetricom.com) GPS RF front end withintegrated synthesizer IC is a key element in a high performance GPS receiver. The front end, implemented on a GST-2 Quick Chip 9-60D, downconverts the RF signal (L1:1575MHz) to a final IF (15.42MHz) with differential output to enable three level adaptive digitization for high receiver selectivity. A low-phase-noise, on-chip, VCO-based frequency synthesizer generates all required on-chip local oscillators. Utilizing a double-conversion superheterodyne with external SAW filters, high levels of image rejection and blocking immunity are possible. Please reference the following technical article for more information: Symmetricom GPS Receiver Front End ASIC with Integrated Synthesizer
Direct-Conversion Tuner ICs for Digital DBS Applications Direct-conversion tuner ICs designed for use in digital direct-broadcastsatellite (DBS) television set-top box units have been achieved using Maxim's high speed bipolar processes. A direct-conversion architecture reduces system cost compared to devices with IF-based architectures. The functional diagram shown below is an example of such a circuit that directly tunes L-band signals to baseband using a broadband I/Q downconverter. Operating frequency range spans from at least 950MHz to 2150MHz. The ICs include a low-noise amplifier (LNA) with automatic gain control (AGC), two downconverter mixers, an oscillator buffer with 900 quadrature generator and prescaler, and baseband amplifiers.
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200 mW Single-Chip Transmitter ICs for 868MHz/915MHz ISM Bands Very high levels of integration are possible on Maxim processes.The MAX2900-2904 single-chip 200mW transmitters are designed for use in the 868 and 915MHz frequency bands. Intended for automated meter reading, but also finding application to a host of other low data rate wireless applications, these transmitter ICs offer a high level of integration, while minimizing the number of external components. This is achieved by full integration of transmit modulator, power amplifier, RF VCO, 8 channel frequency synthesizer, and baseband PN sequence low-pass filter.
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Highly Integrated Transmit IC For Dual-Band Cellular Phones The MAX2369 is a dual-band, triple-mode complete transmitterfor cellular phones. The device takes a differential I/Q baseband input and mixes it up to IF through a quadrature modulator and IF variable-gain amplifier (VGA). The signal is then routed to an external bandpass filter and upconverted to RF through an SSB mixer and RF VGA. The signal is further amplified with an on-board PA driver.
The MAX2369 is designed for dual-band operation and supportsTDMA for the PCS band as well as TDMA and AMPS for the cellular band. The desired mode of operation is selected by loading data on the SPI™/MICROWIRE™-compatible 3-wire serial bus. The MAX2369 then routes the signals to the appropriate ports depending on which band is selected. The MAX2369 includes two RF LO input ports and two PA driver ports, eliminating the need for external switching circuitry.
The MAX2369 takes advantage of the serial bus to set modessuch as charge-pump current, high or low sideband injection, and IF/RF gain balancing. It is packaged in a small (7mm x 7mm) 48-pin QFN package with exposed paddle.
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