TRF2050

The TRF2050 is a low-voltage, low-power consumption 1.2-GHz fractional-N/integer-N frequency synthesizer component for wireless applications. Fractional-N division and an integral speed-up charge pump are used to achieve rapid channel switching. Two operating modes of TRF2050 are available: 1) SA7025 emulation mode in which the part emulates the Philips SA7025 fractional-N synthesizer and 2) extended performance mode (EPM), which provides additional features including fractional accumulator modulos from 1 to 16 (compared to only 5 or 8 for the SA7025) and programmable control of the speed-up mode duration (compared to the SA7025 method of holding the strobe line high).

Along with external loop filters, the TRF2050 provides all functions necessary for voltage-controlled oscillator (VCO) control in a dual phase-locked loop (PLL) frequency synthesizer system. A main channel is provided for radio frequency (RF) channels and an auxiliary channel for intermediate frequency (IF) channels. The current-output charge pumps directly of TRF2050 drive passive resistance-capacitance (RC) filter networks to generate VCO control voltages. Rapid main-channel frequency switching is achieved with a charge pump arrangement that increases the current of TRF2050 drive and alters the loop-filter frequency response during the speed-up mode portion of the switching interval.