MAX1007

19-1180; Rev 0; 6/98 Mobile-Radio Analog Controller ________________General Description The MAX1007 is a multifunctional integrated circuit designed for high-performance mobile radios. It includes one 8-bit analog-to-digital converter (ADC), and two 7-bit and two 6-bit digital-to-analog converters (DACs) for functions including radio-frequency (RF) power sensing and antenna-diversity selection. The ADC provides for power sense, receive-signal strength intensity (RSSI) measurements and system supervision. In the power-sense mode, the ADC converts the power-sensing circuitry signal (representing either the transmitted (Tx) or received (Rx) RF power) into a digital code, ensuring optimum Tx power setting and Rx signal analysis. An additional direct input to the ADC provides for system-supervision measurements, such as power-supply voltages, battery voltage, and temperature. Four DAC blocks typically control DC levels in radios. As part of the Maxim PWT1900 chip set, the two 7-bit DACs control the gain settings and the two 6-bit DACs control the varactor diodes to tune a TCXO and bias a GaAs amplifier. Each DAC register and output can be updated independently, providing maximum flexibility. For antenna diversity, a magnitude-comparison circuit captures and compares two peak signals. A latched logic-comparator output reveals which signal has the largest magnitude. The MAX1007 also includes an onboard voltage reference for the ADC and DACs. The MAX1007 offers a high level of signa...