UT Starcom PHS handset: cordless color calling

The UT Starcom 718-U+ takes the PHS concept to an unusual level of sophistication, adding the color LCD screen, polyphonic audio, and high memory content characteristic of the phone marketplace. Accordingly, much of analog content typical of cell phones is now found in the 718-U+ handset, particularly in support of the radio, power, audio, and display aspects of design.

Radio integration was modest in many respects and discrete RF functional blocks won out over more condensed "and complex"IC components. A mixed-function component from Sony along with devices from JRC and Toshiba form the heart of radio. Two parts from Fujitsu handle frequency synthesis/PLL for channel control"one for transmit and one for receive. The design exhibits notable discrete component complexity to tie the various radio ICs together, highlighting both the ongoing of radio design and the low-integration approach chosen for the UT Starcom design.

Similar to the design philosophy the RF arena, a fairly localized approach to power management is evident. Eight separate regulators from Mitsumi, Ricoh, Toko, and Maxim distributed throughout the design with a battery charge controller chip from ON Semiconductor being one of the more integrated of the power analog components. The LCD panel uses a separate bias voltage generator IC (manufacturer unknown) on the flex assembly for the color display. A National Semi part delivers 1-W amplification to the polyphonic audio supported in the Toshiba-manufactured digital baseband component.

The UT Starcom 718-U+ reflects a design philosophy favoring off-the-shelf components versus chasing high levels of analog integration. While greater component count may imply higher recurring costs versus a more distilled alternative, the often steep costs of ASIC design are sidestepped. As such, the effective costs may be lower when volumes are modest"a possibility with the rapidly changing state of PHS handsets in China.

David Carey is President of Portelligent (www.teardown.com). The Austin, Texas company produces teardown reports and related industry research on Wireless, Mobile, and Personal Electronics.