CX77304-17

The CX77304-17 Power Amplifier Module (PAM) is designed in a compact form factor for tri-band cellular handsets comprising EGSM900, DCS1800, and PCS1900 operation. It also supports Class 10 General Packet Radio Service (GPRS) multi-slot operation.

The PAM CX77304-17 consists of an EGSM900 PA block, a DCS1800/PCS1900 PA block, impedancematching circuitry for 50 Ω input and output, and bias control circuitry. Two separate Heterojunction Bipolar Transistor (HBT) PA blocks are fabricated on a single Gallium Arsenide (GaAs) die. One PA block operates in the EGSM900 band and the other PA block supports both the DCS1800 and the PCS1900 bands. Optimized for lithium ion battery operation, both PA blocks share common power supply pins to distribute current.

A custom CMOS CX77304-17 integrated circuit provides the internal interface circuitry, including a current amplifier that minimizes the required power control current (IAPC) to 10 µA, typical. The GaAs die, the Silicon (Si) die, and passive components are mounted on a multi-layer laminate substrate. The assembly is encapsulated with plastic overmold. The RF input and output ports are internally matched to 50 Ω to reduce the number of external components for a tri-band design. Extremely low leakage current (2 µA, typical) of the dual PA module maximizes handset standby time.

The CX77304-17 also contains band-select switching circuitry to select EGSM (logic 0) and DCS/PCS (logic 1) as determined from the Band Select (BS) signal. In the block diagram shown below, the BS pin selects the PA output (DCS/PCS OUT or EGSM OUT) while the Analog Power Control (APC) controls the level of output power.