Copyright © [2013, 2020] Marki Microwave, Inc. All Rights Reserved.

DOUBLE-BALANCED MIXERS

M9-0942

Page 4

LO/RF 9.0 to 42.0 GHz

IF 1.0 to 22.0 GHz

Downconversion Spurious Suppression

Spurious data is taken by selecting RF and LO frequencies (+mLO+nRF) within the 9 to 42 GHz RF/LO bands, which

create a 2.0 GHz IF spurious output. The mixer is swept across the spurious band and the mean is calculated. The

numbers shown in the table below are for a -10 dBm RF input. Spurious suppression is scaled for different RF power

levels by (n-1)

, where “n” is the RF spur order. For example, the 2RFx2LO spur is 55 dBc for a -10 dBm input (I-Diode),

so a -20 dBm RF input creates a spur that is (2-1) x (-10 dB) dB lower, or 65 dBc.

-10 dBm RF Input

0xLO

1xLO

2xLO

3xLO

4xLO

5xLO

0xRF

-------------

See LO to IF Isolation and LO Harmonic to IF Isolation Plots (Page 3)

1xRF

18 (18)

Reference

30 (30)

14 (13)

32 (32)

22 (27)

2xRF

56 (52)

56 (55)

55 (52)

59 (49)

54 (42)

60 (53)

3xRF

79 (78)

53 (50)

77 (72)

66 (58)

84 (72)

66 (56)

4xRF

105 (105)

90 (92)

94 (84)

100 (89)

100 (87)

106 (91)

5xRF

117 (115)

104 (101)

114 (106)

106 (89)

118 (107)

111 (98)

A sample downconversion spurious sweep is shown below. An LO which is 2.0 GHz higher than the RF is used to create

a 2.0 GHz reference IF. A second LO is used to create a 2x2 spurious IF, also at 2.0 GHz (1.0 GHz fundamental IF).

The difference between these two output levels is the spurious suppression in dBc. The mean value across the 9 to 40

GHz RF input band is the number shown in the table above.

-80

-70

-60

-50

-40

-30

-20

-10

0

5

10

15

20

25

30

35

40

RF Input Frequency (GHz)

2RF x 2LO Spurious Suppression (dBc)

I-Diode

L-Diode

Downconversion 2RFx2LO

Spurious Data Example:

RF Input: 9 to 40 GHz @ -10 dBm

LO for Reference: 11 to 42 GHz

LO for Spurious: 10 to 41 GHz

IF Output: 2.0 GHz