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Startup Berkna builds all-CMOS GSM transceiver

Posted: 02 Sep 2004 ?? ?Print Version ?Bookmark and Share

Keywords:bkw9000? berkna wireless? transceiver?

Silicon Valley startup Berkna Wireless Inc. has unveiled an all-CMOS single-chip transceiver that it believes will address the power, performance, space, cost and multimode flexibility requirements of GSM handsets.

Forming the foundation of a horizontally integrated RF front-end that melds GSM with Wi-Fi or Bluetooth, the device crosses a chasm on the way to the as-yet-unrealized single-chip cellular radio.

Founded in 2001, Berkna is a fabless semiconductor company backed by $30 million in financing to date and a brain trust with more than a hundred patents filed or granted. That said, the startup is going up against proven companies such as Silicon Labs and Skyworks "which already have single-chip GSM transceivers" in a highly competitive market segment where volumes continue to exceed expectations.

Robert Fan, VP of marketing at Berkna, said handheld shipments will exceed market forecasts and top 600 million in 2005, rising to 700 million in 2008. "Operators tell us GSM will continue to be the foundation for their GSM/GPRS/Edge designs," he said.

But Fan also underscored a manufacturing trend: "Companies with a full vertical manufacturing model" such as Nokia "will continue to lose market share to those that are more flexible, and ODMs [and OEMs] are getting very sophisticated and acquiring more expertise." Those ODMs and OEMs are also quick to adopt new technology and are demanding best-in-class components, he said.

When combined with manufacturers' need for multiple-sourced parts, those trends open a window of opportunity for startups such as Berkna, Fan believes.

To widen that window, Berkna focused on an all-CMOS design, despite the noise and sensitivity associated with CMOS, particularly in the context of a tight spec such as GSM. "Doing it in CMOS allows the application of Moore's Law to RF," said Fan, "but it requires a new approach and the application of advanced DSP techniques."

The upside is that CMOS allows further integration with a digital baseband en route to single-chip GSM radio, he said. "But right now we're more focused on the horizontal integration of multiple RF interfaces."

Calibrated design

The final design relied on extensive calibration to account for process and temperature variations, said Cormac Conroy, the company's co-founder and VP of strategic marketing. "The key in CMOS is to push the complexity to the digital domain and be able to design a transmitter and receiver that can have noisy digital switching circuitry on the same chip as RF without degrading the radio performance."

The resulting chip, the BKW9000, is manufactured in an 0.18?m RF CMOS process from Taiwan Semiconductor Manufacturing Co. (TSMC) Ltd and uses a low-IF architecture with digital conversion at the IF stage. It integrates quad-band low-noise amplifiers for GSM-850, EGSM-900, DCS-1800 and PCS-1900 operation, and it includes on-board VCOs, a temperature-controlled digitally compensated crystal oscillator and either a digital or a standard I/Q analog interface to baseband. No external LC filters, transmit filters, transmit baluns, IF SAW filters or VCO modules are required.

Key specifications on the receive side, Conroy said, include a sensitivity of -110dBm, a second-order intercept point in the "high 40s [dBm]," and an IP3 "of around -14dBm or -15dBm." On the transmit side, the key parameter of rms phase error is "typically at 1.4 to 1.5 degrees, going to 1 in the lower band." This compares favorably with the GSM specification of 5, he said.

The chips come in a 7-by-7mm QFN and are sampling now. Production is scheduled for the fourth quarter. The unit price is $4.50 in volumes of 10,000.

- Patrick Mannion

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