Electronic Design

What's new in the Q?

Motorola partnered with Cingular Wireless when it introduced its ultra-slim RAZR and SLVR handsets, and both of those Global System for Mobile Communications (GSM) phones were based on chip sets from Freescale Semiconductor. But Motorola's decision to pair up with Verizon Wireless on a Windows Mobile-based smartphone – the Moto Q (see Figure)– dictated a CDMA design. That "pretty much narrowed the choice" of a chip-set provider to Qualcomm, according to teardown specialist David Carey at Portelligent Inc. The only Freescale device in the Q is the MC13883, an integrated charger, USB On-the-Go transceiver, and car kit interface.

Carey said the RF side of the Q is built around Qualcomm's MSM6500 baseband processor. It's a two-chip device consisting of a digital baseband/DSP and an analog baseband chip that handles analog-to-digital and digital-to-analog conversion. The analog chip is stacked on top of the digital baseband within the package.

Two Qualcomm RF processors, the RFT6100 and RFT6000, handle transmit and receive functions respectively. The company says that the PM6650 power-management chip eliminates the need for a dozen or more voltage regulators. A Qualcomm RFL6000 low-noise amplifier boosts incoming signals from the phone's antenna, and two gallium-arsenide monolithic microwave IC (MMIC) RF power amplifiers from Skyworks Solutions – the CX77140 and CX77112 – handle 800-MHz and 1900-MHz bands. The CX77140 meets IS95 CDMA linearity requirements to a minimum of 28.0-dBm output power and can be driven to levels beyond 31 dBm for high efficiency in FM mode. The CX77112 meets spectral linearity requirements of CDMA/PCS transmission up to 29-dBm output power.

The Qualcomm baseband chip set is supported by a two-chip Intel RD38F4050 memory package that contains a 32-Mbyte NOR flash chip for the Q's operating system and an 8-Mbyte PSRAM volatile memory.

The Q uses the cdma2000 1X EV-DO (1X-EV Phase One) protocol, in which voice and data ride on separate channels and data is delivered at 2.4 Mbits/s. Motorola reportedly has a UMTS version of the Q in development, with an introduction planned before the end of this year.

The Moto Q's Windows Mobile 5.0 functions run on a 312-MHz Intel XScale-based PXA270 applications processor. The PXA270 is the first XScale device to include wireless MMX technology for multimedia acceleration. The chip also features SpeedStep power management and a camera interface based on Intel's Quick Capture technology.

Memory for the applications processor is provided by an M-Systems disk-on-chip that contains two 64-Mbyte NAND flash chips and two 32-Mbyte SDRAM chips stacked together. Carey noted that M-Systems, an outfit that Sandisk is slated to acquire, has developed NAND devices that are randomly addressable. "The NAND/SDRAM combination is analogous to the hard drive and memory in a PC," Carey said. "Code is moved from NAND into SDRAM when the Q is turned on, and code is executed from there."

Three chips from Texas Instruments also support the Q's Windows Mobile functions. One is an analog ASIC (TWL93017C) that integrates audio and power management. According to Carey, "Motorola has used the TI ASIC previously in other phones." The other two TI chips are TPA2010 audio amplifiers, which drive the phone's stereo speakers.

"The magic in the Moto Q is less in the electronics than in how they went about doing the mechanical packaging," Carey said. "The electronics are sophisticated, but there is nothing inside the Q that has not been used in other phones – except that other phones don't have the ultra-slim (11.5 mm) mystique of the Q."

"Designers of thin form-factor phones at Motorola and elsewhere have had to get creative in the way they arrange components," noted Andrew Rassweiler, who heads the teardown group at iSuppli.

"In the RAZR, for example, Motorola packed the bulk of the phone's electronics very densely on a small main PCB \[pc board\] nestled at the bottom of the lower portion of the handset – the section that extends below the keypad. A flex keypad PCB and flexible electroluminescent (EL) backlight also contributed to the RAZR's trim profile," Rassweiler said. The lower half of each side of the Moto Q's main pc board is populated with active electronics, with the remainder of the real estate dedicated to accommodating the display module, keypad, and lithium-ion battery (Fig. 1).

"Now where they got a little creative was in mating a secondary Bluetooth and memory-card PCB right over the active area of the main PCB (Fig. 2), which gives the board two tiers of functional area in the same quadrant," Rassweiler explained. "This is creative, but not unique in trying to pack more functionality into a very small shoe."

"One luxury that Motorola had in developing the Q is that the phone resembles a PDA, with a larger than cell phone-sized screen and a QWERTY-like keyboard, which amounts to relatively large real estate. That is one reason why swapping the current Q chip set for a GSM/UMTS chip set would not be overly difficult," Portelligent's Carey added.

"The Moto Q is very thin, but not very small," Carey continued. "It uses relatively high-density packaging, but it's not at the high limit of component densification. The keyboard and LCD set the form factor and open real estate for electronics. There is more empty green space in the Q than there is in other designs (Fig. 3)."

Carey explained that the Moto Q contains a total of nearly 700 components – "two or three times the number of components in a voice-centric phone." The parts include more than 60 ICs; 28 small active components, such as diodes, transistors, and LEDs; over three-dozen odd-form components and modules (crystal oscillators, voltage-controlled oscillators, infrared (IR) receivers, and switches and buttons), and 561 passive components and connectors, ranging from one- or two-pin devices to 40-pin parts.

"Motorola obviously thought quite carefully about how to eliminate as much ‘dead' air space as possible and partition the electronics to make the Q so thin," Carey said. The phone contains a circuit board dedicated to the keyboard, and the main pc board contains most of the electronics. However, the 1.3 Mpixel camera, the antenna module, and other subsystems are "chopped up," according to Carey, divided among a larger than usual number of smaller boards that are nested in ways that minimize the phone's profile.

The main pc board takes up most of the length of the phone. Motorola placed components on both sides of the board, but none underneath the portion of the board where the battery sits. A daughtercard, placed so as not to add thickness, holds the memory-card slot.

Carey said Motorola backed the Q's keypad with a sheet of electroluminescent (EL) film that provides uniform illumination while also contributing to the phone's low profile. "If they had used LEDs, they would have needed a diffuser panel – another sheet of plastic – to spread the light evenly."

The phone's 117-mm (4.6-in.) length benefited its design. "It provides room at both ends," Carey said. "A stereo speaker assembly rests inside one of the antennas at the bottom of the phone, and the camera and earpiece are at the top. None of those components rest on top of the main PCB."

The Moto Q includes four antennas for 800 MHz, 1900 MHz, Bluetooth, and GPS (Assisted GPS is built into the Qualcomm chip set), all internal, and all fashioned from stamped/formed metal. "The antennas fit snugly against the case and don't consume a lot of volume," Carey said.

The case itself has the look and feel of metal but is made of plastic. Carey added, "The endoskeleton – formed from the combination of boards, battery and display – is pretty stiff, and when they are bonded together, they offer quite a bit of rigidity, so the exoskeleton can be less exotic."

Related Links
Cingular Wireless
www.cingular.com

Freescale Semiconductor
www.freescale.com

Intel Corporation
www.intel.com

iSuppli Corporation
www.isuppli.com

M-Systems
www.m-systems.com

Portelligent Inc.
www.teardown.com

Qualcomm Incorporated
www.qualcomm.com

Sandisk Corporation
www.sandisk.com

Skyworks Solutions Inc.
www.skyworksinc.com

Texas Instruments Incorporated
www.ti.com

Verizon Wireless
www.verizonwireless.com


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