Two-Chip Radio Solution for TD-SCDMA Cellular Phones.
This TD-SCDMA chipset is the industry's first two-chip solution for the domestic Chinese TD-SCDMA market. The MAX2392 is the industry's first direct-conversion receiver for TD-SCDMA. The MAX2507 is the first production-ready, fully spec-compliant, SiGe transmit IC to include a power amplifier and meet the tough cellular performance requirements for TD-SCDMA. These devices are being referenced in a majority of the TD-SCDMA designs today. The MAX19700 family of baseband data converters completes the chipset for designs that do not have the baseband data conversion integrated onto the baseband processor of choice.
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| Application Notes |
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| Frequently Asked Questions |
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What are the key performance areas of the MAX2392 that make it a good fit for the TD-SCDMA market?
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- 90dB dynamic range
- 32mA Rx current (excellent standby time)
- 2.3dB cascaded noise figure
- On-chip DC offset cancellation
- 200µs PLL lock time (from 15MHz away)
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What are the key performance areas of the MAX2507 that make it a good fit for the TD-SCDMA market?
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- >80dB dynamic range
- ACPR ±1.6MHz = -38dBc (typ)
- ACPR ±3.2MHz = -48dBc (typ)
- <200mA low-power output ICC (including PA)
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How was the difficult PA circuit integrated into the MAX2507?
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A combination of Maxim's proprietary SiGe process and circuit technologies allowed us to accomplish this. The PA is not a separate die, but is monolithic with the rest of the Tx chain.
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How can the MAX2392 be configured for the handset Rx idle mode?
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- Choice 1: It can use the idle-mode feature of the chip (11mA, 150µs PLL lock time).
- Choice 2: It can utilize bit SHDN feature (<20µA, 300µs PLL lock time).
(*Choice 2 is recommended by Maxim for maximum standby time.)
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Can the MAX2392 and MAX2507 accommodate the difficult back-to-back Tx/Rx slot requirement for TD-SCDMA?
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Testing shows that the devices can accommodate this requirement. The MAX2392 has a programmable highpass filter for DC offset correction. During the Tx slot, RxAGC can be pulled low to 0.5V; then, during the following Rx slot, the DC offset can settle in <5µs using the wide BW setting (~1MHz) on the highpass filter. Once DC offset is settled, the highpass filter can be programmed back to a narrow setting (~20kHz) for the Rx slot operation.
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How have the devices performed in field trials?
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The MAX2392/MAX2507 are currently in field trials in nine phones in China. No issues have been reported thus far. Field trials on all phones will finish by the end of October, 2005.
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Are there any special software requirements for the MAX2507/MAX2392?
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The handset software must be sure to program the test register to its proper default value (0370 hex) after each power-up. See the corresponding data sheets for more details.
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When will the TD-SCDMA market take off in China?
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There may be some delays as the infrastructure is rolled out in China, but Maxim expects to ramp these devices to full volume in the first half of 2006.
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