TQ5121 View Datasheet(PDF) - TriQuint Semiconductor

Part Name

Description

Manufacturer

TQ5121

3V Cellular TDMA/AMPS LNA/mixer Receiver IC

TriQuint Semiconductor 

TQ5121

Data Sheet

Mixer IF Port

The Mixer IF output is an "open-drain" configuration, allowing for

flexibility in efficient matching to various filter types and at

various IF frequencies.

For evaluation of the LNA and mixer, it is usually necessary to

impedance match the IF port to the 50Ω test systems. When

verifying or adjusting the matching circuit on the prototype circuit

board, the LO drive should be injected at pin 4 at the nominal

power level of -7 dBm, since the LO level does have an impact

on the IF port impedance.

There are several networks that can be used to properly match

the IF port to the SAW or crystal IF filter. The mixer supply

voltage is applied through the IF port, so the matching circuit

topology must contain either an RF choke or shunt inductor. An

extra DC blocking capacitor is not necessary if the output will be

attached directly to a SAW or crystal bandpass filters.

Figure 7 shows the IF matching network, A shunt L, series C,

shunt C, is the simplest and requires the fewest components.

DC current can be easily injected through the shunt inductor and

the series C provides a DC block, if needed. The shunt C, is

used to reduce the LO leakage.

Fig 7. IF Output Match (110MHz)

Pin 14

10pF

180nH

8.2pF

0.01uF 10Ω

Mx IF

out

Vdd

Note: These values assume ideal components and neglect board parasitics.

The discrepancy between these values and those of the typical application

circuit are the board and component parasitics

8

For additional information and latest specifications, see our website: www.triquint.com

Share Link: