Linear Technology 1233A Series, 1233A-A, 1233A-B, LT5579, 1233A-D Quick Start Manual

QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 1233A-X

-A

WiMAX

456MHz

Low-side 3.6GHz

-B WiMAX

456MHz

High-side 2.6GHz

-C

UMTS

240MHz

High-side 2.14GHz

-D

PCS 240MHz

Low-side 1.95GHz

Supply Voltage

3.3V

Supply Current

226mA

LO Input Frequency Range

1.1GHz to 4GHz

LO Input Power

-

5 to +2dBm

1233A

-A

1233A

-B

1233A

-C

1233A

-D

WiMAX 3.6GHz

WiMAX 2.6GHz

UMTS

PCS

IF Input Frequency Range

12dB Return Loss, LO applied

330 to 505MHz

330 to 505MHz

174 to 263MHz

174 to 263MHz

RF Output Frequency Range

10dB Return Loss,

LO applied

3170 to 4100MHz

2260 to 2780MHz

2035 to 2285MHz

1840 to 2020MHz

Conversion Gain

-

0.5dB

1.3dB 2.6dB 1.9dB

Conversion Gain vs. Temperature

T = -40°C to 85°C

-0.027dB/°C

-0.027dB/°C

-0.020dB/°C

-0.020dB/°C

Output 3rd Order Intercept

23.2dBm

26.2dBm

27.3dBm

28dBm

Output 2nd Order Intercept

54dBm

45dBm

42dBm

40dBm

Single Sideband Noise Figure

12dB 12dB 9.9dB 9.9dB

Output Noise Floor

P = -5dBm

-155.5dBm/Hz

-157.5dBm/Hz

-158.1dBm/Hz

-158.1dBm/Hz

Output 1dB Compression

10.7dBm

13.7dBm

13.9dBm

13.6dBm

IF to LO Isolation

73dB 74dB 81dB 80dB

LO to IF Leakage

-

22dBm

-26dBm

-28dBm

-25dBm

LO to RF Leakage

-

35dBm

-36dBm

-35dBm

-34dBm

DESCRIPTION

1.5GHZ TO 3.8GHZ HIGH LINEARITY UPCONVERTING MIXER

LT5579

Demonstration circuit 1233A-x is a high linearity up­converting mixer featuring the LT5579.

The LT®5579 is a high performance upconverting mixer
IC optimized for output frequencies in the 1.5GHz to

The DC1233A-x series of demonstration circuits are
designed for evaluating the LT5579 IC at several com­mon frequency ranges:

VERSION APPLICATION IF INPUT LO INPUT RF OUTPUT

3.8GHz range. It features single-ended LO input and RF
output ports to simplify board layout and to reduce sys­tem cost.

The LT5579 offers a superior alternative to passive mix­ers. Unlike passive mixers which have conversion loss
and require high LO drive levels, the LT5579 delivers
conversion gain at significantly lower LO input levels
and is less sensitive to LO power level variations. Only

-1dBm of LO power is needed, and the balanced design

Demonstration circuit 1233A-x can be easily optimized
for operations at other frequencies. Refer to the “Appli­cation Note” section and the LT5579 data sheet for de­tails.

results in low LO signal leakage to the RF output. The
lower LO drive level requirements, combined with the
excellent LO leakage performance, translate into lower
LO signal contamination of the output signal.

Table 1. Typical Demo Circuit Performance Summary (TA = 25°C, VCC = 3.3V, P
PLO = -1dBm, unless otherwise noted. Low side LO for 1950MHz and 3600MHz. High side LO for 2140MHz and 2600MHz.)

PARAMETER CONDITIONS TYPICAL PERFORMANCE

Design files for this circuit board are available. Call
the LTC factory.

, LT, LTC, and LTM are registered trademarks of Linear Technology Corp.

All other trademarks are the property of their respective owners.

= -5dBm (-5dBm/tone for 2-tone tests,

IF

∆∆∆∆

f = 1MHz),

1

QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 1233A-X

1.5GHZ TO 3.8GHZ HIGH LINEARITY UPCONVERTING MIXER

APPLICATION NOTE

ABSOLUTE MAXIMUM RATINGS

Supply Voltage......................................................3.6V

LO Input Power.............................................. +10dBm

LO Input DC Voltage .................... -0.3V to VCC + 0.3V

RF Output DC Current........................................ 60mA

IF Input Power (Differential).......................... +13dBm

IF+, IF- DC Currents ........................................... 60mA

T

.................................................................150°C

JMAX

Operating Temperature Range.............. -40°C to 85°C

Storage Temperature Range............... -65°C to 150°C

IF INPUT INTERFACE

The standard demonstration circuit 1233A-x can be re­configured for other IF input frequencies. The details of
the matching circuit are omitted in this guide, since the
LT5579 datasheet presents in depth explanations and
the IC’s IF input differential impedance. Matching com­ponent values for several common IF input frequencies
are listed in Table 2. Refer to the demonstration circuit
schematic in Figure 3.

Table 2. IF Input Component Values

IF Freq.

(MHz)

140

240

450

NOTE:

C1,C2

(pF)

70 1000 120 (2) 4.7nH 100 9.1

1000 120 (2)

C9 (1)

(pF)

82 33 (2)

33 33 (2)

C3

(pF)

TL1,TL2

(3)

Z0=70

Ω

Z0=70Ω

Z0=70Ω

L1,L2

R1,R2

(nH)

100 9.1

(

40 11

40 11

ΩΩΩΩ

)

3.

The 70Ω microstrip transmission line TL1 and TL2
provide inductances required for matching. At lower
frequencies, external inductors are necessary.

4.

R1 and R2 set the DC current in the mixer core to the
optimum level of 50mA per side. Their values should
be well matched for best LO leakage performance.

0.1% tolerance is recommended.

5.

L1 and L2 reduce the loading effect of R1 and R2.
Their self-resonant frequency should be at least sev­eral times the IF frequency. High quality wire-wound
type inductors are recommended. The DC resis­tances of L1 and L2 need to be accounted for in the
selection of R1 and R2.

LO INPUT INTERFACE

The LT5579’s LO input port is internally matched from

1.1GHz to 4GHz, with a minimum return loss across
this range of about 9dB at 2.3GHz. External matching
should be used for lower LO frequencies for best per­formance. Refer to the LT5579 datasheet for more in­formation and impedance data.

RF OUTPUT INTERFACE

The LT5579 utilizes an internal RF transformer to step
down the mixer core output impedance to simply RF
output matching. Matching component values for sev­eral common RF output frequencies are listed in Table

3. High quality precision microwave capacitors, such
as the AVX Accu-p series, should be used for C8 to
minimize parasitics.

1.

Center of C9 is 3mm from the edge of the IC package
for all cases.

2.

C3 is a small-valued capacitor used to improve the
LO-RF leakage in some applications, and it has little
effect on impedance matching. C3’s value and loca­tion depend on LO and RF frequencies and are de­termined experimentally. In certain instances, two
common-mode capacitors to ground instead of one
single differential capacitor may provide better leak­age suppression.

Table 3. RF Output Component Values

RF Frequency (MHz) C8 (pF) L3 (nH)

1650 1.5 6.8

1750

1950

2140

2600

3600

1.2 6.8

1 4.7

0.45 3.9

- 1.0

0.7

0Ω

2

QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 1233A-X

1.5GHZ TO 3.8GHZ HIGH LINEARITY UPCONVERTING MIXER

TEST EQUIPMENT AND SETUP

The LT5579 is a high linearity upconverting mixer IC.
Accuracy of its performance measurement is highly
dependent on equipment setup and measurement tech­nique. The following precautions are recommended:

1.

Use high performance signal generators with low
harmonic output. Otherwise, utilize low-pass fil­ters at the signal generator outputs to suppress
higher-order harmonics.

2.

Turn off the signal generators’ output automatic­level-control (ALC). This prevents conflict in
power-level control between the two sources,
which can introduce intermodulation products.

3.

High quality combiners that provide broadband

50ΩΩΩΩ termination on all ports and have good port-

to-port isolation should be used. Attenuators on
the outputs of the signal generators are recom­mended to further improve source isolation to
prevent the sources from modulating each other
and generating intermodulation products.

4.

Beware of the signal generators’, and if used, source
amplifiers’ 1dB compression point. When driven
close to their 1dB compression point, the sources
and amplifiers may introduce additional distortions.

5.

The level of intermodulation products from the input
sources needs to be much lower than the products
expected to be generated by the DUT. In general, IM
products measured at the input connector to the DUT
should be 25dB or more below the expected level at
the DUT output.

6.

If possible, use small attenuator pads with good
VSWR on the demonstration circuit’s input and
output ports to improve source and load match to
reduce reflections, which may degrade measure­ment accuracy.

7.

Use narrow resolution bandwidth (RBW) and en­gage video averaging on the spectrum analyzer to
lower the displayed average noise level (DANL) in
order to improve sensitivity and to increase dy­namic range. The trade off is increased sweep
time.

8.

Spectrum analyzers can produce significant internal
distortion products if they are overdriven. Generally,
spectrum analyzers are designed to operate at their
best with about –30dBm to -40dBm at their input fil­ter or preselector.
put attenuation should be used to avoid saturating
the instrument, but too much attenuation reduces
sensitivity and dynamic range.

9.

Before performing measurements on the demo
circuit, the system performance should be evalu­ated to ensure that: 1) clean input signal can be
produced, 2) the spectrum analyzer’s internal dis­tortion is minimized, 3) the spectrum analyzer has
enough dynamic range and sensitivity, and 4) the
system is accurately calibrated for power and fre­quency.

Sufficient spectrum analyzer in-

3