1997-11-10 ,

With the introduction today of the UBA1710M RF Power Modulator IC for mobile phones, Philips Semiconductors, the largest European semiconductor manufacturer, gives designers the option of a high-performance single-chip solution to the control and protection of GaAs power amps. Targeted primarily for use with the company's highly successful CGY2021G 2-watt MMIC Power Amplifier, the UBA1710M provides the RF power control required in DCS/PCS handsets, while at the same time reducing their size, weight and manufacturing costs. With other GaAs power amplifiers from Philips Semiconductors' CGY20xx range, it can also be used in handsets for systems such as GSM.

Although GaAs MESFETs remain the most commonly used device for RF power amplification in mobile phones, they previously required several peripheral circuits to make them work. Designers had to provide a DC/DC converter to generate a negative bias voltage, circuitry to control the RF power level, and some means of reducing the leakage current through the MESFETs when the power amp is inactive. The UBA1710M replaces all these components with a single IC.

"Used with the CGY2021G Power Amp IC, the UBA1710M provides mobile phone designers with one of the most compact and power efficient 4.8-volt RF power amp designs on the market," said product marketing manager Jean-Marc Lemenager. "Compared to other GaAs solutions, this combination provides an additional 1.5 dBm of saturated power gain while keeping the drive power to 0 dBm."

Instead of modulating the gate voltage of the power amp's MESFETs to control the RF power level, the UBA1710M controls their drain voltage via an integrated power MOSFET. Closed-loop feedback to the MOSFET via an on-chip buffer amplifier allows the high-speed adjustment of power levels required in phone systems such as GSM and DCS. The same MOSFET that is used to modulate the power level also isolates the power amp from its positive supply rail when the power amp is turned off.

The UBA1710M also incorporates an on-chip DC/DC converter that generates a -1.8 V gate bias for the power amp MESFETs, plus power management logic that sequences the application of the gate and drain voltages to the power amp. It therefore protects the power amplifier from possible damage by preventing excessive current flow in the MESFETs during power up.

A power amplifier using the UBA1710M Modulator and CGY2021G GaAs Power Amplifier IC is capable of achieving a power added efficiency of 50% and a saturated power output in excess of 34.5 dBm.

Packaged in a 20-lead shrink small-outline package (SSOP) surface-mount package, the UBA1710M costs around US$ 1.5 per piece in a volume of 10k pieces. The price for a UBA1710M/CGY2021G RF power amplifier kit amounts to around US$ 5.0 in a volume of 10 k pieces. The UBA1710M is a fabricated in an advanced BiCMOS process and is designed and manufactured at Philips Semiconductors' facilities in Caen, France.

Philips Semiconductors, a division of Philips Electronics NV, headquartered in Eindhoven, The Netherlands, is the ninth largest semiconductor supplier in the world and the third largest supplier of discretes in the world. Philips Semiconductors' innovations in digital audio, video, and mobile technology position the company as a leader in the consumer, multimedia and wireless communications markets. Sales offices are located in all major markets around the world and are supported by systems labs.