Texas Instruments TRF1500 - Manual (Page 38)

SWRA004A
TRF1500 Integrated Dual-Band RF Receiver User’s Guide 39
High-Band LO Buffer Amplifier Output
Figure 16 details the high-band LO buffer amplifier configuration.
The high-band LO buffer can be used in either single-ended or
differential mode for a phase lock loop (PLL) configuration. The
buffer is digitally controlled and requires an operating drive level
ranging from -3 to -7dBm. 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 for dc blocking.
The transmission line on the output of the buffer amplifier are used
to convert the 100
Ω
differential to 50
Ω
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 microstip lines can be
calculated with standard transmission line equations using the
following values:
The following information are used to calculate the microstrip
transmission lines:
Frequency = 2.070 GHz
ER = 4.400 (FR4), Height = 12.0000 mils, Thickness = 1.5000 mils
(Copper)
Electrical Parameters:
ZO = 35.350, E_EFF = 90.000
Results:
Physical Parameters:
Width = 37.777, Length = 771.149
Figure 16. High-Band LO Buffer Amplifier Output Configuration