TQ5M31 View Datasheet(PDF) - TriQuint Semiconductor
Part Name
Description
MFG CO.
'TQ5M31' PDF : 16 Pages View PDF
-30
-32
-34
-36
-38
-40
-42
700 800 900 1000 1100 1200
Frequency (MHz)
Figure 4. LO Buffer Response
The absolute value isn't important, since it depends on the
probe's distance from the pin (it is usually around -30 dB), but
the peak of the response should be centered in the middle of
the L0 frequency band. Increasing the inductance will lower
the center frequency, and vice versa.
GIC Pin (Pin 2)
To tune the TQ-5M31 to a specific Gain, IP3, and DC Current
configuration, the designer should follow these steps:
1] Choose the desired OIP3. The OIP3 should be less than
18dBm.
2] Determine how much current is required to achieve the
desired OIP3 from table 1. Data presented in these tables are
approximate. The designer is only to use these tables as a
guideline, keeping in mind that gain roll off will occur at higher
RF and IF frequencies.
3] From the same table, determine the required total
resistance for the GIC pin (R3+R4) in the figure below.
Table 1: OIP3 vs. total resistance (R3+R4)
OIP3 (dBm)
Idd (mA) Resistance (ohms)
18
15
20
15
7
80
12
5.5
130
9
5
160
6
4
240
3
3.5
320
TQ5M31
Data Sheet
4] The designer should start with a “reasonably high”
capacitor for C7 bypass, typical value 150pF. For an IF in the
range of 85 to 210 Mhz, a 150 pF capacitor is acceptable.
5] Note that R3 is the unbypassed resistor on the GIC pin.
Since the total resistance for R3+R4 has been chosen, the
only parameter to decide is the ratio of R3 to R4. This ratio
determines the gain of the mixer. While keeping R3+R4
constant, decreasing R3 while increasing R4 will result in
more gain. For maximum gain, R3 can be replaced with a
wire, and all of the R3+R4 resistance would reside on R4.
This results in a single resistor in parallel with a capacitor on
the GIC pin. In general, most applications result in R4 >
R3. The designer can determine experimentally in very short
order which resistor configuration to use.
See performance curves, page 4, “GIC tuning plot”.
GIC pin
R3
C7
R4
6] After the components on the GIC pin have been
determined, the IF matching should be evaluated.
Mixer LO Port (Pin 3)
A common gate buffer amplifier between the LO port and the
mixer FET gate provides a good impedance for the VCO and
to allows operation at lower LO drive levels. The buffer
amplifier provides enough voltage gain to drive the gate of the
mixer FET while consuming very little current (~1mA).
Because of the good broadband 50Ω input impedance of the
buffer amplifier, and the internal DC blocking capacitor, the
user’s VCO can be directly connected to the LO input via a
50Ω line with no additional components. The physical length
of this connection is not critical.
For additional information and latest specifications, see our website: www.triquint.com
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