Texas Instruments TRF1500 Low-BandLO Buffer Amplifier Output, Low-BandIF Output Configuration

SWRA004A

Figure 9. Low-Band IF Output Configuration

Low-Band LO Buffer Amplifier Output

Figure 10 details the low-band LO buffer amplifier configuration. The low-band LO buffer amplifier can be used in either single- ended or differential mode for a phase lock loop (PLL) configuration. The buffer is digitally controlled and requires a operating drive level ranging from -3 to -7 dBm. For evaluation purposes, a 1:1 transformer balun, with an insertion loss of 2.7 dB, is used to convert the differential output to a single-ended output. The series capacitors at the buffer output are used for dc blocking.

The transmission line on the output of the buffer amplifier are used to convert the 100Ω differential to 50Ω differential.

The transmission lines on the output of the buffer amplifier can be modeled as microstrip lines. The values used for the calculations depend on the PCB substrate, the board stackup and the required impedance. The physical dimensions of the microstrip lines can be calculated using standard microstrip transmission line equations using the following values:

Frequency = 990 MHz

ER = 4.400 (FR4), Height = 12.0000 mils , Thickness = 1.5000 mils (Copper)

Electrical Parameters:

ZO = 35.350 Ohms, E_EFF = 90.000

Physical Parameters:

Width = 37.777 mils , Length = 1613.305 mils

24 TRF1500 Integrated Dual-Band RF Receiver User’s Guide