9

RF

IF

LO

RFC

Bypass

Capacitor

IF

Output

Figure 26. Available Conversion Gain and SSB Noise Figure vs. Device Current

(Source Resistor).

The DC bias is also applied to the mixer through the IF

port. Figure 5 shows how an inductor (RFC) is used to

isolate the IF from the DC supply. The bias line is bypassed

to ground with a capacitor to keep RF off of the DC supply

lines and to prevent dips or peaks in the response of the

mixer.

Figure 25. Bias Connection.

LO Port

The LO input port is internally matched to 50 Ω within a

.: VSWR over the entire operating frequency range. Ad-

ditional matching will normally not be needed. However,

if desired, a small series inductor can be used to provide

some improvement in the LO match and thus reduce the

LO drive level requirement by up to 0.7 dB. Reflection co-

efficients for the LO port are shown in the table of Typical

Reflection Coefficients.

Source Bypass Pin

The Source Bypass pin should be RF bypassed to ground

at both the RF and LO frequencies as well as the IF. Many

capacitors with values large enough to adequately bypass

lower intermediate frequencies contain parasitics that

may have resonances in the RF band. It is often practical

to use two capacitors in parallel for this purpose instead

of one. A small value, high quality capacitor is used to by-

pass the RF/LO frequencies and a large value capacitor for

the IF. When biased in the high linearity mode, a resistor is

added from the Source Bypass pin to ground.

High Linearity Mode

The IAM-9563 has a feature that allows the user to place

an external resistor from the Source Bypass pin to ground

and increase the device current from a nominal 9 mA to

as high as 0 mA. The additional current increases mixer

linearity (IP

at higher device current is shown in Figures 6 and 7.

Figure 27. One dB Compression and Input Third Order Intercept Point vs. De-

vice Current (Resistor).

As an example of improved linearity, the use of a 5 Ω re-

sistor at the Source Bypass pin increases the device cur-

rent to 4 mA. At .9 GHz, the input IP

-6.5 dBm to -3 dBm. Increasing the LO drive level from -5

dBm to - dBm further increases the input IP

7

13

15

17

9

11

19

4

6

8

10

14

12

DEVICE CURRENT (mA)

Figure 26. Available Conversion Gain and SSB Noise

Figure vs. Device Current (Source Resisitor).

1000

9

5

3

56

21

Approximate Resistor Value ( )

NF

GAIN

7

13

15

17

9

11

19

1000

9

5

3

56

21

-10

-8

-6

-4

0

-2

DEVICE CURRENT (mA)

Approximate Resistor Value ( )

Figure 27. One dB Compression and Input Third Order

Intercept Point vs. Device Current (Resistor).

IP3

P1 dB