Product category: Communications ICs (Wireless)
News Release from: Maxim Integrated Products | Subject: MAX2021/MAX2023 and MAX2058/MAX2059
Edited by the Electronicstalk Editorial Team on 31 August 2006
Chipset cuts basestation transmitter
down to size
High-performance SiGe I/Q modulator and digital RF variable-gain amplifier chipset is designed specifically for GSM/Edge basestation transmitter applications.
Maxim Integrated Products has developed a high-performance SiGe I/Q modulator and digital RF variable-gain amplifier (VGA) chipset designed specifically for GSM/Edge basestation transmitter applications Together, the MAX2021/MAX2023 I/Q modulators and the MAX2058/MAX2059 VGAs deliver the lowest noise and highest levels of linearity of any competing direct-conversion (zero-IF) transmitter solution
This article was originally published on Electronicstalk on 27 Aug 2002 at 8.00am (UK)
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Designers are constantly searching for more cost-effective solutions that simultaneously reduce component count, board size, and design complexity.
For GSM/Edge base transceiver system (BTS) transmitters, the most cost-effective solution utilises a direct baseband-to-RF (ie zero-IF) architecture.
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However, due to the basestation's demanding spectral mask requirements, zero-IF architectures have historically been limited to low-performance handset applications.
With the introduction of the MAX2021/MAX2023 and MAX2058/MAX2059 series of high-performance I/Q modulators and RF digital VGAs, the historical performance barrier for GSM zero-IF architectures has finally been breached.
Together with the company's MAX5873 dual DAC and MAX4395 quad amplifier, these new components form the industry's first and only digital baseband-to-RF VGA chipset that meets all spectral-mask and noise-floor requirements for single-carrier GSM850/900 and DCS1800/PCS1900 Edge basestations.
When cascaded together, the complete chipset delivers +15dBm of output power, +32dBm of OIP3, and an exceptionally low output-noise level of -156dBc/Hz maximum (at 6MHz offset).
LO leakage (nulled) is also rated at -40dBc maximum over the extended -40 to +85C temperature range.
Complete lineup gain control is provided by the SPI-controlled RF digital VGAs, as the two on-chip attenuators support 12dB of static control, 30dB of dynamic control, and at least 10dB of lineup compensation.
The chipset's noise and linearity performance is driven primarily by the new MAX2021/MAX2023 zero-IF I/Q modulators.
Both modulators boast breakthrough output-noise-density levels of -174dBm/Hz that match the theoretical thermal limit.
These outstanding levels represent an astounding 10dB improvement over prior state-of-the-art modulators/demodulators.
In addition, the MAX2021/MAX2023 yield OIP2, OIP3, and OP1dB levels of up to 57.9/61, 22.3/23.5 and 16.7/14.3dBm, respectively.
When you couple the noise performance with the raw P1dB values, the gross dynamic range is greater than 190.7/188.3dB - a 16.7/14.3dB performance leap over the closest competitors.
These performance improvements directly enhance a BTS transmitter's spectral mask performance, and they allow the MAX2021/MAX2023 to exceed the strict spectral-mask requirements for GSM/EDGE BTS applications without the use of relatively expensive transmit mask filters (approximately US $2.00 each, in volumes of 100,000 or more).
The performance of the MAX2058/MAX2059 RF digital VGAs is equally impressive.
Each device yields 62/56dB of total adjustment range, +15dBm of output power, 32.3/31.8dBm of OIP3, and a low spurious emission of -39.2/-39.1dBc at a 200kHz offset, respectively.
Even more noteworthy is their degree of integration.
Besides the two digital attenuators and the two-stage RF amplifiers, these VGAs include an on-chip SPI decoder, two loopback switches, and a novel loopback mixer.
When paired with the Company's MAX9491 synthesiser, the loopback mixer provides a convenient means for translating the transmit signal frequency up or down so that it can be fed directly into the receiver band.
With this unique feature, the system can be configured for simultaneous, real-time diagnostic monitoring of both the transmitter and receiver chains.
As with all zero-IF transmit architectures, the company's basic four-chip solution replaces a myriad of components.
compared with a traditional double upconversion transmit architecture, this new solution replaces six lineup functions with a net cost savings of 65% (comparison made with replaced components).
The Maxim chipset also only requires 26 x 27mm of board space, resulting in a 50% space savings over a comparable circuit function.
The cost and space savings, in turn, enable the next generation of GSM/Edge designs in which transceiver price and density issues are paramount.
The MAX2021/MAX2023 and MAX2058/MAX2059 are available in 36-TQFN and 40-TQFN packages, respectively.
Prices start at $4.98 (1000-up, FOB USA) for the MAX2021/MAX2023 and $7.96 (1000-up, FOB USA) for the MAX2058/MAX2059.
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