LT5503EFE#PBF - Linear Technology

LT5503

5503f

APPLICATIO S

FEATURES

TYPICAL APPLICATIO

DESCRIPTIO

MODOUT

0°

90°

÷2

÷1

CONTROL

LOGIC

GC1 GC2GND

–

LO2

2.45GHz

BPF

CC1

CC2

2.45GHz

MODULATED

RFOUT

–

MODV

RFV

LO1V

LO2 MODIN

LT5503

VGA

LO1

LO1IN (2075MHz)

LO2IN

(750MHz)

DMODE

MIXEN

MODEN

MIXER

ENABLE

MODULATOR

ENABLE

5503 TA01

VGA

■

IEEE 802.11 DSSS and FHSS

■

High Speed Wireless LAN (WLAN)

■

Wireless Local Loop (WLL)

■

PCS Wireless Data

■

MMDS

■

Single 1.8V to 5.25V Supply

■

Direct IQ Modulator with Integrated 90° Phase

Shifter*

■

Four Step RF Power Control

■

120MHz Modulation Bandwidth

■

Independent Double-Balanced Mixer

■

Modulation Accuracy Insensitive to Carrier Input

Power

■

Modulator I/Q Inputs Internally Biased

■

Available in 20-Lead FE Package

1.2GHz to 2.7GHz Direct

IQ Modulator and Mixer

The LT

5503 is a front-end transmitter IC designed for low

voltage operation. The IC contains a high frequency quadra-

ture modulator with a variable gain amplifier (VGA) and a

balanced mixer. The modulator includes a precision 90°

phase shifter which allows direct modulation of an RF

signal by the baseband I and Q signals.

In a superheterodyne system, the mixer can be used to

generate the high-frequency RF input for the modulator by

mixing the system’s 1st and 2nd local oscillators.

The LT5503 modulator output P 1dB is –3dBm at 2.5GHz.

The VGA allows output power reduction in three steps up

to 13dB with digital control. The baseband inputs are

internally biased for maximum input voltage swing at low

supply voltage. If needed, they can be driven with external

bias voltages.

2.45GHz Transmitter Application, Carrier for Modulator Generated by Upmixer

SSB Output Power vs

I, Q Amplitude

I, Q DIFFERENTIAL INPUT VOLTAGE (VP-P)

0.01

SSB OUTPUT POWER (dBm)

–5

–10

–15

–20

–25

–30

–35

–40

–45

5503 G04

0.1 10

5.25 VDC 3 VDC

1.8 VDC

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

All other trademarks are the property of their respective owners. *Patent Pending

LT5503

5503f

TOP VIEW

–

GC1

MODIN

MOD

LO1

DMODE

–

GC2

MODOUT

VGA

LO2

MODEN

MIXEN

–

FE PACKAGE

20-LEAD PLASTIC TSSOP

Supply Voltage ...................................................... 5.5V

Control Voltages .......................... –0.3V to (V

+ 0.3V)

Baseband Voltages (BI

to BI

–

and BQ

to BQ

–

) ...... ±2V

Baseband Common Mode Voltage .....1V to (V

– 0.3V)

LO1 Input Power .................................................. 4dBm

LO2 Input Power .................................................. 4dBm

MODIN Input Power ............................................. 4dBm

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

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

Lead Temperature (Soldering, 10 sec).................. 300°C

JMAX

= 150°C, θ

= 38°C/W

EXPOSED PAD IS GND (PIN 21)

MUST BE SOLDERED TO PCB

ABSOLUTE AXI U RATI GS

(Note 1)

ORDER I FOR ATIO

UUW

PI CO FIGURATIO

UUU

LEAD FREE FINISH TAPE AND REEL PART MARKING PACKAGE DESCRIPTION TEMPERATURE RANGE

LT5503EFE#PBF LT5503EFE#TRPBF 5503 20-Lead Plastic TSSOP –40°C to 85°C

Consult LTC Marketing for parts specified with wider operating temperature ranges.

Consult LTC Marketing for information on nonstandard lead based finish parts.

For more information on lead free part marking, go to: http://www.linear.com/leadfree/

For more information on tape and reel specifications, go to: http://www.linear.com/tapeandreel/

LT5503

5503f

ELECTRICAL CHARACTERISTICS

VCC1 = 3VDC, 2.4GHz matching, MODEN = High, GC1 = GC2 = Low, TA = 25°C, MODRFIN = 2.45GHz at –16dBm, [I – IB] and [Q – QB] =

100kHz CW signal at 1VP-P differential, Q leads I by 90°, unless otherwise noted. (Test circuit shown in Figure 2.) (Note 3)

(I/Q Modulator)

PARAMETER CONDITIONS MIN TYP MAX UNITS

RF Carrier Input (MODRFIN)

Frequency Range

Requires Appropriate Matching 1.2 to 2.7 GHz

Input VSWR Z

= 50Ω1.3:1

Input Power –20 to -10 dBm

Baseband Inputs (BI

, BI

–

, BQ

–

)

Frequency Bandwidth (3dB) 120 MHz

Differential Input Voltage for 1dB Compressed Output 1 V

P-P

DC Common-Mode Voltage Internally Biased 1.4 VDC

Differential Input Resistance 18 kΩ

Input Capacitance 0.8 pF

Gain Error ±0.2 dB

Phase Error ±1 DEG

Modulated RF Carrier Output (MODRFOUT)

Output Power, Max Gain –6 –3 dBm

Output VSWR Z

= 50Ω1.5:1

Image Suppression –26 –34 dBc

Carrier Suppression –24 –32 dBc

Output 1dB Compression –3 dBm

Output 3rd Order Intercept f

= 100kHz, f

= 120kHz 2 dBm

Output 2rd Order Intercept f

= 100kHz, f

= 120kHz 16 dBm

Broadband Noise 20MHz Offset –142 dBm/Hz

VGA Control Logic (GC2, GC1)

Switching Time 100 ns

Input Current 2μA

Input Low Voltage 0.4 VDC

Input High Voltage 1.7 VDC

Output Power Attenuation GC2 = Low, GC1 = High 4.5 dB

Output Power Attenuation GC2 = High, GC1 = Low 9 dB

Output Power Attenuation GC2 = High, GC1 = High 13.5 dB

Modulator Enable (MODEN) Low = Off, High = On

Turn ON/OFF Time 1μs

Input Current 105 μA

Enable V

– 0.4 VDC

Disable 0.4 VDC

Modulator Power Supply Requirements

Supply Voltage 1.8 5.25 VDC

Modulator Supply Current MODEN = High 29 38 mA

Modulator Shutdown Current MODEN = Low 50 μA

LT5503

5503f

Note 1: Stresses beyond those listed under Absolute Maximum Ratings

may cause permanent damage to the device. Exposure to any Absolute

Maximum Rating condition for extended periods may affect device

reliability and lifetime.

Note 2: External component values on the final test circuit shown in

Figure 2 are optimized for operation in the 2.4GHz to 2.5GHz band.

Note 3: Specifications over the –40°C to 85°C temperature range are

assured by design, characterization and correlation with statistical process

controls.

ELECTRICAL CHARACTERISTICS

VCC2 = 3VDC, 2.4GHz matching, MIXEN = High, DMODE = Low (LO2 ÷ 2 mode), TA = 25°C, LO2IN = 750MHz at –18dBm, LO1IN =

2075MHz at –12dBm. MIXRFOUT measured at 2450MHz, unless otherwise noted. (Test circuit shown in Figure 2.) (Note 3)

PARAMETER CONDITIONS MIN TYP MAX UNITS

Mixer 2nd LO Input (LO2IN)

Frequency Range Internally Matched 50 to 1000 MHz

Input VSWR Z

= 50Ω1.4:1

Input Power –20 to –12 dBm

Mixer 1st LO Input (LO1IN)

Frequency Range

Requires Appropriate Matching 1400 to 2400 MHz

Input VSWR Z

= 50Ω1.5:1

Input 3rd Order Intercept –30dBm/Tone, Δf = 200kHz –12 dBm

Mixer RF Output (MIXRFOUT)

Frequency Range

Requires Appropriate Matching 1700 to 2700 MHz

Output VSWR Z

= 50Ω1.5:1

Small-Signal Conversion Gain P

LO1

= –30dBm 5 dB

Output Power –14.7 –12.7 dBm

LO1 Suppression – 22 – 29 dBc

Output 1dB Compression –15 dBm

Broadband Noise 20MHz Offset –152 dBm/Hz

LO2 Divider Mode Control (DMODE) Low = f

LO2

÷ 2, High = f

LO2

÷ 1

Input Current 1μA

Input Low Voltage (÷2) 0.4 VDC

Input High Voltage (÷1) V

– 0.4 VDC

Mixer Enable (MIXEN) Low = Off, High = On

Turn ON/OFF Time 1μs

Input Current 130 μA

Enable V

– 0.4 VDC

Disable 0.4 VDC

Mixer Power Supply Requirements

Supply Voltage 1.8 5.25 VDC

Supply Current (÷2 mode) DMODE = Low, MIXEN = High 11.9 15.5 mA

Supply Current (÷1 mode) DMODE = High, MIXEN = High 10.8 mA

Shutdown Current MIXEN = Low 10 μA

(Mixer)

LT5503

5503f

TYPICAL PERFOR A CE CHARACTERISTICS

Modulator Supply Current vs

Supply Voltage Modulator Shutdown Current vs

Supply Voltage

MODEN Current vs Enable

Voltage

Baseband Frequency Response

I/Q Amplitude = 1VP-P

MODRFIN and MODRFOUT

Return Loss 2.4GHz Matching

Typical SSB Spectrum

CC1

SUPPLY VOLTAGE (V)

1.8

SUPPLY CURRENT (mA)

3.2 4.6 5.3

5503 G01

2.5 3.9

= 85°C

= 25°C

= –40°C

CC1

SUPPLY VOLTAGE (V)

1.8

SHUTDOWN CURRENT (μA)

3.2 4.6 5.3

100

0.1

5503 G02

2.5 3.9

= 85°C

= 25°C

= –40°C

MODEN = LOW

MODEN VOLTAGE (V)

1.8

INPUT CURRENT (μA)

3.2 4.6 5.3

220

200

180

160

140

120

100

5503 G03

2.5 3.9

= 85°C

= –40°C

MODEN = V

CC1

= 25°C

I, Q INPUT FREQUENCY (MHz)

OUTPUT POWER (dBm)

–5

–10

–15

–20

–25

–30

–35

–40

5503 G05

0.1 10

IMAGE

CARRIER

DESIRED

SIDEBAND

FREQUENCY (MHz)

2050

RETURN LOSS (dB)

–20

–10

2850

5503 G06

–30

–40 2250 2450 2650

MODRFOUT

MODRFIN

VCC1 = 3VDC, 2.4GHz matching, MODEN = high, GC1 = GC2 = low (max gain), TA = 25°C, MODRFIN = 2.45GHz at –16dBm, (I–IB) and

(Q–QB) = 100kHz sine at 1VP-P differential, Q leads I by 90°, unless otherwise noted. (Test circuit shown in Figure 2.)

(I/Q Modulator)

FREQUENCY (MHz)

–10

–20

–30

–40

–50

–60

–70

–80

–90

–100

OUT

(dBm)

5503 G07

2449.6 2449.8 2450.0 2450.2 2450.4 2450.6

SUPPLY VOLTAGE (V)

1.8

OUTPUT POWER (dBm)

–2

–3

–4

–5

–6 2.4 3.0 3.6 4.2

5503 TA01b

4.8 5.4

PLO1 = –12dBm

PLO2 = –18dBm

BASEBAND = 1VP-P

TA = 25°C

2.45GHz Modulated Output

Power vs Supply Voltage

LT5503

5503f

TYPICAL PERFOR A CE CHARACTERISTICS

SSB Output Power vs Input Power

VCC1 = 1.8V

Carrier Suppression vs Input Power

VCC1 = 1.8V

SSB Output Power vs Input Power

VCC1 = 3V

Carrier Suppression vs Input Power

VCC1 = 3V

Image Suppression vs Input Power

VCC1 = 3V

SSB Output Power vs Input Power

VCC1 = 5.25V

Carrier Suppression vs Input Power

VCC1 = 5.25V

Image Suppression vs Input Power

VCC1 = 5.25V

MODRFIN INPUT POWER (dBm)

–24 –22 –20 –18 –16 –14 –12 –10

SSB OUTPUT POWER (dBm)

–2

–4

–6

–8

–10

–12

–14

–16

–18

–20

5503 G08

TA = 85°C

TA = 25°C

TA = –40°C

MODRFIN INPUT POWER (dBm)

–24 –22 –20 –18 –16 –14 –12 –10

CARRIER SUPPRESSION (dBc)

–20

–30

–40

–50

5503 G09

= 85°C

= 25°C

= –40°C

MODRFIN INPUT POWER (dBm)

–24 –22 –20 –18 –16 –14 –12 –10

IMAGE SUPPRESSION (dBc)

–20

–30

–40

–50

5503 G10

= 85°C

= 25°C

= –40°C

MODRFIN INPUT POWER (dBm)

–24 –22 –20 –18 –16 –14 –12 –10

SSB OUTPUT POWER (dBm)

–2

–4

–6

–8

–10

–12

–14

–16

–18

5503 G11

= 85°C

= 25°C

= –40°C

MODRFIN INPUT POWER (dBm)

–24 –22 –20 –18 –16 –14 –12 –10

CARRIER SUPPRESSION (dBc)

–20

–30

–40

–50

5503 G12

= 85°C

= 25°C

= –40°C

MODRFIN INPUT POWER (dBm)

–24 –22 –20 –18 –16 –14 –12 –10

IMAGE SUPPRESSION (dBc)

–20

–30

–40

–50

5503 G13

= 85°C

= 25°C

= –40°C

MODRFIN INPUT POWER (dBm)

–24 –22 –20 –18 –16 –14 –12 –10

SSB OUTPUT POWER (dBm)

–2

–4

–6

–8

–10

–12

–14

–16

–18

5503 G14

= 85°C

= 25°C

= –40°C

MODRFIN INPUT POWER (dBm)

–24 –22 –20 –18 –16 –14 –12 –10

CARRIER SUPPRESSION (dBc)

–20

–30

–40

–50

5503 G15

= 85°C

= 25°C

= –40°C

MODRFIN INPUT POWER (dBm)

–24 –22 –20 –18 –16 –14 –12 –10

IMAGE SUPPRESSION (dBc)

–20

–30

–40

–50

5503 G16

TA = 85°C

TA = 25°C

TA = –40°C

Image Suppression vs Input

Power VCC1 = 1.8V

2.4GHz matching, MODEN = high, GC1 = GC2 = low (max gain), MODRFIN = 2.45GHz, (I–IB) and (Q–QB) = 100kHz sine at 1VP-P

differential, Q leads I by 90°, unless otherwise noted. (Test circuit shown in Figure 2.)

(I/Q Modulator)

LT5503

5503f

TYPICAL PERFOR A CE CHARACTERISTICS

Output Power vs Frequency

1.2GHz Matching

Carrier Feedthrough vs Frequency

1.2GHz Matching

SSB Image vs Frequency

1.2GHz Matching

Output Power vs Frequency

1.9GHz Matching

Carrier Feedthrough vs Frequency

1.9GHz Matching

SSB Image vs Frequency

1.9GHz Matching

Output Power vs Frequency

2.4GHz Matching

Carrier Feedthrough vs Frequency

2.4GHz Matching

SSB Image vs Frequency

2.4GHz Matching

MODRFIN FREQUENCY (MHz)

1000 1100 1200 1300 1400

SSB OUTPUT POWER (dBm)

–2

–4

–6

–8

–10

–12

–14

–16

–18

–20

5503 G17

GC2, GC1 = 00

MODRFIN FREQUENCY (MHz)

1000 1100 1200 1300 1400

5503 G18

CARRIER (dBm)

–30

–40

–50

–60

GC2, GC1 = 00

MODRFIN FREQUENCY (MHz)

1000 1100 1200 1300 1400

5503 G19

IMAGE (dBm)

–30

–40

–50

–60

GC2, GC1 = 00

MODRFIN FREQUENCY (MHz)

1650 1750 1850 20501950 2150

SSB OUTPUT POWER (dBm)

–2

–4

–6

–8

–10

–12

–14

–16

–18

5503 G20

GC2, GC1 = 00

MODRFIN FREQUENCY (MHz)

1650 1750 1850 20501950 2150

5503 G21

CARRIER (dBm)

–30

–40

–50

–60

GC2, GC1 = 00

MODRFIN FREQUENCY (MHz)

1650 1750 1850 20501950 2150

5503 G22

IMAGE (dBm)

–30

–40

–50

–60

GC2, GC1 = 00

MODRFIN FREQUENCY (MHz)

2250 2350 2450 26502550

SSB OUTPUT POWER (dBm)

–2

–4

–6

–8

–10

–12

–14

–16

–18

5503 G23

GC2, GC1 = 00

MODRFIN FREQUENCY (MHz)

2250 2350 2450 26502550

5503 G24

GC2, GC1 = 00

CARRIER (dBm)

–30

–40

–50

–60

MODRFIN FREQUENCY (MHz)

2250 2350 2450 26502550

5503 G25

GC2, GC1 = 00

IMAGE (dBm)

–30

–40

–50

–60

VCC1 = 3VDC, MODEN = high, TA = 25°C, PMODRFIN = –16dBm, (I–IB) and (Q–QB) = 100kHz sine at 1VP-P differential, Q leads I by 90°,

unless otherwise noted. (Test circuit shown in Figure 2.)

(I/Q Modulator)

LT5503

5503f

TYPICAL PERFOR A CE CHARACTERISTICS

Mixer Supply Current vs Supply

Voltage (LO2 ÷ 2 Mode)

Mixer Supply Current vs Supply

Voltage (LO2 ÷ 1 Mode)

Mixer Shutdown Current vs Supply

Voltage

RF Output Power vs LO1 Input

Power (VCC2 = 1.8V)

RF Output Power vs LO1 Input

Power (VCC2 = 3V)

RF Output Power vs LO1 Input

Power (VCC2 = 5.25V)

LO1 Feedthrough vs LO1 Input

Power (VCC2 = 1.8V)

LO1 Feedthrough vs LO1 Input

Power (VCC2 = 3V)

LO1 Feedthrough vs LO1 Input

Power (VCC2 = 5.25V)

VCC2 SUPPLY VOLTAGE (V)

1.8

SUPPLY CURRENT (mA)

82.5 3.2 4.63.9

5503 G26

5.3

TA = 85°C

TA = 25°C

TA = –40°C

CC2

SUPPLY VOLTAGE (V)

1.8

SUPPLY CURRENT (mA)

82.5 3.2 4.63.9

5503 G27

5.3

= 85°C

= 25°C

= –40°C

DMODE = HIGH

CC2

SUPPLY VOLTAGE (V)

1.8

SHUTDOWN CURRENT (μA)

100

0.1 2.5 3.2 4.63.9

5503 G28

5.3

= 85°C

= 25°CT

= –40°C

MIXEN = LOW

LO1IN POWER (dBm)

–30

MIXRFOUT POWER (dBm)

–6

1195 G29

–24 –18 –12 –9

–27 –21 –15

–12

–14

–16

–18

–20

–22

–24

–26

–28

= 85°C

= –40°C

= 25°C

LO1IN POWER (dBm)

–30

MIXRFOUT POWER (dBm)

–6

1195 G30

–24 –18 –12 –9

–27 –21 –15

–12

–14

–16

–18

–20

–22

–24

–26

–28

= 85°C

= –40°C

= 25°C

LO1IN POWER (dBm)

–30

MIXRFOUT POWER (dBm)

–6

1195 G31

–24 –18 –12 –9

–27 –21 –15

–12

–14

–16

–18

–20

–22

–24

–26

–28

= 85°C

= –40°C

= 25°C

LO1IN POWER (dBm)

–30

LO1 FEEDTHROUGH (dBc)

–6

1195 G32

–24 –18 –12 –9

–27 –21 –15

–20

–25

–30

–35

–40

= 85°C

= –40°C

= 25°C

LO1IN POWER (dBm)

–30

LO1 FEEDTHROUGH (dBc)

–6

1195 G33

–24 –18 –12 –9

–27 –21 –15

–20

–25

–30

–35

–40

= 85°C

= –40°C

= 25°C

LO1IN POWER (dBm)

–30

LO1 FEEDTHROUGH (dBc)

–6

1195 G34

–24 –18 –12 –9

–27 –21 –15

–20

–25

–30

–35

–40

= 85°C

= –40°C

= 25°C

2.4GHz matching, MIXEN = high, DMODE = low (LO2 ÷ 2 mode), LO2IN = 750MHz at –18dBm, LO1IN = 2075MHz. MIXRFOUT measured

at 2450MHz, unless otherwise noted. (Test circuit shown in Figure 2.)

(Mixer)

LT5503

5503f

TYPICAL PERFOR A CE CHARACTERISTICS

RF Output Power and LO1

Feedthrough 1.9GHz Matching

Small-Signal Conversion Gain

and IIP3 1.9GHz Matching

LO1IN and MIXRFOUT Return Loss

1.9GHz Matching

RF Output Power and LO1

Feedthrough 2.4GHz Matching

Small-Signal Conversion Gain

and IIP3 2.4GHz Matching LO1 and MIXRFOUT Return Loss

2.4GHz Matching

MIXEN Input Current vs Enable

Voltage (MIXEN = VCC2)

RF OUTPUT FREQUENCY (MHz)

1650

RF OUTPUT (dBm)

–12

–14

–16

–18

–20

–22

–10

–20

–30

–40

–50

2050

5503 G35

1750 1850 1950 2150

OUTPUT

POWER

LO1

FEEDTHROUGH

LO2IN = 480MHz AT –18dBm

LO1IN = fRF –240MHz AT –12dBm

LO1 (dBc)

RF OUTPUT FREQUENCY (MHz)

1650

CONVERSION GAIN (dB)

–2

–4

–3

–6

–9

–12

–15

–18

2050

5503 G36

1750 1850 1950 2150

IIP3

SMALL-SIGNAL

CONVERSION

GAIN

LO2IN = 480MHz AT –18dBm

LO1IN = fRF –240MHz AT –30dBm/TONE

IIP3 (dBm)

FREQUENCY (MHz)

1100

RETURN LOSS (dB)

–5

–10

–15

–20

–25

–30 1700 2100

5503 G37

1300 1500 1900 2300 2500

LO1IN

MIXRFOUT

RF OUTPUT FREQUENCY (MHz)

2250

RF OUTPUT (dBm)

–12

–14

–16

–18

–20

–22

–10

–20

–30

–40

–50

2650

5503 G38

2350 2450 2550

LO1

FEEDTHROUGH

OUTPUT

POWER

LO2IN = 750MHz AT –18dBm

LO1IN = f

–375MHz AT –12dBm

LO1 (dBc)

RF OUTPUT FREQUENCY (MHz)

2250

CONVERSION GAIN (dB)

–2

–4

–3

–6

–9

–12

–15

–18

2650

5503 G39

2350 2450 2550

IIP3

SMALL-SIGNAL

CONVERSION

GAIN

LO2IN = 750MHz AT –18dBm

LO1IN = f

–375MHz AT –30dBm/TONE

IIP3 (dBm)

FREQUENCY (MHz)

1450

RETURN LOSS (dB)

–5

–10

–15

–20

–25

–30 2050 2450

5503 G40

1650 1850 2250 2650 2850

LO1

MIXRFOUT

MIXEN VOLTAGE (V)

1.8

INPUT CURRENT (μA)

3.2 4.6 5.3

300

270

240

210

180

150

120

5503 G41

2.5 3.9

= 85°C

= –40°C

= 25°C

VCC2 = 3VDC, MIXEN = high, DMODE = low (LO2 ÷ 2mode), TA = 25°C, unless otherwise noted. (Test circuit shown in Figure 2.)

(Mixer)

LT5503

5503f

PI FU CTIO S

–

(Pin 1): Negative Baseband Input Pin of the Modulator

Q-Channel. This pin is internally biased to 1.4V, but can

also be overdriven with an external DC voltage greater than

1.4V, but less than V

– 0.4V.

(Pin 2): Positive Baseband Input Pin of Modulator Q-

Channel. This pin is internally biased to 1.4V, but can also

be overdriven with an external DC voltage greater than

1.4V, but less than V

– 0.4V.

GC1 (Pin 3): Gain Control Pin. This pin is the least

significant bit of the four-step modulator gain control.

MODIN (Pin 4): Modulator Carrier Input Pin. This pin is

internally biased and should be AC-coupled. An external

matching network is required for a 50Ω source.

MOD (Pin 5): Power Supply Pin for the I/Q Modulator.

This pin should be externally connected to the other V

pins and decoupled with 1000pF and 0.1μF capacitors.

RF (Pin 6): Power Supply Pin for the I/Q Modulator

Input RF Buffer and Phase Shifter. This pin should be

externally connected to the other V

pins and decoupled

with 1000pF and 0.1μF capacitors.

LO1 (Pin 7): Mixer 1st LO Input Pin. This pin is internally

biased and should be AC-coupled. An external matching

network is required for a 50Ω source.

LO1 (Pin 8): Power Supply Pin for the Mixer LO1

Circuits. This pin should be externally connected to the

other V

pins and decoupled with 1000pF and 0.1μF

capacitors.

DMODE (Pin 9): Mixer 2nd LO Divider Mode Control Pin.

Low = divide-by-2, High = divide-by-1.

(Pin 10): Mixer Positive RF Output Pin. This pin must

be connected to V

through an external matching net-

work.

–

(Pin 11): Mixer Negative RF Output Pin. This pin must

be connected to V

through an external matching net-

work.

MIXEN (Pin 12): Mixer Enable Pin. When the input voltage

is higher than V

– 0.4V, the mixer circuits supplied

through pins 8, 10, 11 and 15 are enabled. When the input

voltage is less than 0.4V, these circuits are disabled.

MODEN (Pin 13): Modulator Enable Pin. When the input

voltage is higher than V

– 0.4V, the modulator circuits

supplied through pins 5, 6, 16 and 17 are enabled. When

the input voltage is less than 0.4V, these circuits are

disabled.

LO2 (Pin 14): Mixer 2nd LO Input Pin. This pin is internally

biased and should be AC-coupled. An external matching

network is not required, but can be used for improved

matching to a 50Ω source.

LO2 (Pin 15): Power Supply Pin for the Mixer LO2

Circuits. This pin should be externally connected to the

other V

pins and decoupled with 1000pF and 0.1μF

capacitors.

VGA (Pin 16): Power Supply Pin for the Modulator

Variable Gain Amplifier. This pin should be externally

connected to the other V

pins through a 47Ω resistor

and decoupled with a good high frequency capacitor (2pF

typical) placed close to the pin.

MODOUT (Pin 17): Modulator RF Output Pin. This pin

must be externally biased to V

through a bias choke. An

external matching network is required to match to 50Ω.

GC2 (Pin 18): Gain Control Pin. This pin is the most

significant bit of the four-step modulator gain control.

(Pin 19): Positive Baseband Input Pin of the Modulator

I-Channel. This pin is internally biased to 1.4V, but can also

be overdriven with an external DC voltage greater than

1.4V, but less than V

– 0.4V.

–

(Pin 20): Negative Baseband Input Pin of the Modula-

tor I-Channel. This pin is internally biased to 1.4V, but can

also be overdriven with an external DC voltage greater than

1.4V, but less than V

– 0.4V.

Exposed Pad (Pin 21): Circuit Ground Return for the

Entire IC. This must be soldered to the printed circuit board

ground plane

LT5503

5503f

BLOCK DIAGRA

0°

90°

5503 BD

MIXER BIAS CIRCUITS

MODULATOR BIAS CIRCUITS

LO1

BUFFER

CONTROL

LOCIC

VGA

V-I V-I

÷2

LIM LIM

÷1

21 10 11 9

2 1 20 19

BQ+BI+

BQ–

MX+MX–DMODEGND

(BACKSIDE)

BI–

VCCMOD

VCCVGA

MODOUT

GC2

GC1

MODEN

MIXEN

VCCLO2

LO2

VCCRF

MODIN

VCCLO1

LO1

LT5503

5503f

Figure 1. Test Schematic for 1.2GHz, 1.9GHz and 2.4GHz Applications

LO1IN

LO2IN

LT5503

5503 F01

234

C13

8.2pF

C43

8.2pF

MIXRFOUT

–

GC1

MODIN

MOD

LO1

DMODE

–

GC2

MODOUT

VGA

LO2

MODEN

MIXEN

–

C5 C6

C10

C20

1000pF

C16

1μF

C18

1μF

MODEN

MIXEN

C15

1μF

C17

1μF

C22

1000pF

2.2pF C7

C19

0.01μF

C23

C14

100pF

GC1 GC2

MODRFIN

MODRFOUT

C11

C12

1000pF

C21

0.01μF

CC2

CC1

DMODE

47Ω

NOTE: V

CC1

AND V

CC2

POWER THE

MODULATOR AND UPMIXER

SECTIONS RESPECTIVELY.

GND

21 (BACKSIDE)

TEST CIRCUIT

Application Dependent Component Values

1.2GHz Matching

(Modulator Only) 1.9GHz Matching 2.4GHz Matching

L1 33nH 22nH 18nH

L2 12nH 5.6nH 2.7nH

L3 12nH 4.7nH 2.7nH

C2, C3, C7 39pF 15pF 8.2pF

C10 2.7pF 1.8pF 1.2pF

C23 n/a 1.5pF 1.5pF

R1 240Ω390Ω390Ω

C4 n/a 15pF 8.2pF

C5, C6 n/a 1.8pF 2.2pF

C9 n/a 15pF 2.7pF

C11 n/a 2.2pF 1.2pF

L4 n/a 6.8nH 4.7nH

L5,L6 n/a 5.6nH 2.2nH

T1 n/a LDB211G9010C-001 LDB212G4005C-001

LT5503

5503f

APPLICATIO S I FOR ATIO

WUUU

The LT5503 consists of a direct quadrature modulator and

a mixer. The mixer operates over the range of 1.7GHz to

2.7GHz, and the modulator operates with an output range

of 1.2GHz to 2.7GHz. The LT5503 is designed specifically

for high accuracy digital modulation with supply voltages

as low as 1.8V. It is suitable for IEEE 802.11b wireless local

area network (WLAN), MMDS and wireless local loop

(WLL) transmitters.

A dual-conversion RF system requires two local oscilla-

tors to convert signals between the baseband and RF

domains (see Figure 2). The LT5503’s double-balanced

mixer can be used to generate the LT5503 modulator’s

high frequency carrier input (MODRFIN) by mixing the

systems 1st and 2nd local oscillators (LO1 and LO2). In

this case, a bandpass filter is required to select the desired

mixer output for the modulator input. The mixer’s RF

differential output produces –12dBm typically at 2.45GHz

and the modulator MODIN pin requires ≥ –16dBm, driven

single-ended. This allows approximately 4dB margin for

Figure 2. Example System Block Diagram for a Dual Conversion System

5503 F02

90°

0°

90°

÷2

÷1

÷2

1ST LO 2ND LO

D/A

A/D

LT5502

LT5506

LT5500

LT5503

LNA

VGA

bandpass filter loss. The balanced output from the modu-

lator is applied to a variable gain amplifier (VGA) that

provides a single-ended output. Note that the modulator

can also be used independently of the mixer, freeing the

mixer to be used anywhere in the system. In this case,

MODRFIN will be driven from an external frequency source.

Modulator Baseband

The baseband I and Q inputs (BI

/BI

–

and BQ

/BQ

–

) are

internally biased to 1.4V to maximize the input signal

range at low supply voltage. This bias voltage is stable over

temperature, and increases by approximately 50mV at the

maximum supply voltage. The modulator I and Q inputs

have very wide bandwidth (120MHz typical), making the

LT5503 suitable for even the most wideband modulation

applications. For best carrier suppression and lowest

distortion, differential input drive should be used. Single-

ended drive is possible too, with the unused inputs AC-

coupled to ground.

LT5503

5503f

APPLICATIO S I FOR ATIO

WUUU

AC-Coupled Baseband

. Figure 3 shows the simplified

circuit schematic of a high-pass AC-coupled baseband

interface.

5505 F03

18k

0.8pF

–

CPL

LT5503

Figure 3. AC-Coupled Baseband Interface

With approximately 18k of differential input resistance,

the suggested minimum AC-coupling capacitor can be

determined using the following equation:

CPL

18 10

(• ••)π

where f

is the 3dB cut-off frequency of the baseband input

signal.

A larger capacitor may be used where the settling time of

charging and discharging the AC-coupling capacitor is not

critical.

DC-Coupled Baseband

. The baseband inputs’ internal bias

voltage can be overdriven with an external bias circuit.

This facilitates direct interfacing to a D/A converter for

faster transient response. In this case, the LT5503’s

baseband inputs are DC biased by the converter. The

optimal V

BIAS

is 1.4V, independent of V

. In general, the

maximum V

BIAS

should be less than V

– 0.4V. The DC

load on each converter output can be approximated using

the following equation where I

INPUT

is the current flowing

into a modulator input:

IVV

INPUT BIAS

=−

Figure 4 shows a simplified circuit schematic for interfac-

ing the LT5503’s baseband inputs to the outputs of a D/A

converter. OIP and OIN are the positive and negative

baseband outputs, respectively, of the converter’s

I-channel. Similarly, OQP and OQN are the positive and

negative baseband outputs, respectively, of the converter’s

Q-channel.

5505 F04

18k

0.8pF

BQ+

BQ–

BI+

BI–

LT5503

IINPUT

OIP

OIN

OQP

OQN

D/A

Figure 4. DC-Coupled Baseband Interface

Modulator RF Input (MODRFIN)

The modulator RF input buffer is driven single-ended. An

internal active balun circuit produces balanced signals to

drive the integrated phase shifter. Limiters following the

phase shifter output accommodate a wide range of

MODRFIN power, resulting in minimal degradation of

modulation gain/phase accuracy performance or carrier

feedthrough. This pin is easily matched to a 50Ω source

with the simple lowpass network shown in Figure 1. This

pin is internally biased, therefore an AC-coupling capaci-

tor is required.

Modulator VGA (Variable Gain Amp)

The VGA has two digital selection lines to provide a

nominal 0dB, 4.5dB, 9dB and 13.5dB attenuation from the

maximum modulator output power setting. The logic table

is shown below:

GC2

Attenuation Low High

GC1 Low 0dB 9dB

High 4.5dB 13.5dB

LT5503

5503f

APPLICATIO S I FOR ATIO

WUUU

Pin 16 should be connected externally to V

through a

low value series resistor (47Ω typical). To assure proper

output power control, a good, local high frequency AC

ground for Pin 16 is essential. The MODOUT port of the

VGA is an open collector configuration. An inductor with

high self resonance frequency is required to connect

Pin 17 to V

as a DC return path, and as a part of the

output matching network. Additional matching compo-

nents are required to drive a 50Ω load as shown in

Figure 1. The amplifier is designed to operate in Class A for

low distortion performance. The typical output 1dB com-

pression point (P1dB) is –3dBm at 2.45GHz. When the

differential baseband input voltages are higher than 1V

P-P

the VGA operates in Class AB mode, and the distortion

performance of the modulator is degraded. The logic

control inputs do not draw current when they are low. They

draw about 2μA each when high.

Mixer LO1 Port

The mixer LO1 input port is the linear input to the mixer.

It consists of an active balun amplifier designed to operate

over the 1.4GHz to 2.4GHz frequency range. There is a

linear relationship between LO1 input power and

MIXRFOUT power for LO1 input levels up to approximately

–20dBm. After that, the mixer output begins to compress.

When operated in the recommended –14dBm to –8dBm

input power range, the mixer is well compressed, which in

turn creates a stable output level for the modulator input.

As shown in Figure 1, a simple lowpass matching network

is required to match this pin to 50Ω. This pin is internally

biased, therefore an AC-coupling capacitor is required.

Mixer LO2 Port

The mixer LO2 port is designed to operate in the 50MHz to

1000MHz range. The first stage is a limiting amplifier. This

stage produces the correct output levels to drive the

internal divider circuit reliably, with LO2 input levels down

to –20dBm. The output of the divider then drives another

stage, which in turn switches the nonlinear inputs of the

double-balanced mixer. Note that the mixer output will

produce broadband noise if the LO2 signal level is too low.

The input amplifier is designed for a good match over the

entire frequency range. The only requirement (Figure 1) is

an external AC-coupling capacitor.

Mixer Output Ports (MX

/MX

–

)

The mixer output is a differential open collector configura-

tion. Bias current is supplied to these two pins through the

center tap of a balun as shown in Figure 1. Simple lowpass

matching is used to transform each leg of the mixer output

to 25Ω for the balun’s 50Ω input impedance.

The balun approach provides the highest output power

and best LO1 suppression, but is not absolutely neces-

sary. It is also possible to match each output to 50Ω and

couple power from one output. The unused output should

be terminated in the same characteristic impedance. In

this case, output power is approximately 2dB lower and

LO1 suppression degrades to approximately 15dBc. A

schematic for this approach is shown in Figure 6 where

inductors LB

and LB

–

supply bias current to the mixer’s

differential outputs, and resistor R

TERM

terminates the

unused output.

5503 F05

10 11

RTERM

51Ω

LB+

MX+MX–

LB–

VCC

CBYPASS

MIXRFOUT

Figure 5. 50Ω Mixer Output Matching Without a Balun

1.9GHz 2.4GHz

L5,L6 5.6nH 2.7nH

C5, C6 1.8pF 0.68pF

C9 15pF 8.2pF

LT5503

5503f

APPLICATIO S I FOR ATIO

WUUU

EVALUATION BOARD

Figure 6 shows the circuit schematic of the evaluation

board. The MODRFIN, MODRFOUT and MIXRFOUT ports

are matched to 50Ω at 2.45GHz. The LO1IN port is

matched to 50Ω at 2.1GHz and the LO2IN port is internally

matched.

A 390Ω resistor is used to reduce the quality factor (Q) of

the modulator output and deliver an output power of

–3dBm typically. A lower value resistor may be used if the

desired output power is lower. For example, the output

power will be 3dB lower if a 200Ω resistor is used.

Inductors with high self-resonance frequency should be

used for L1 to L6.

For simpler evaluation in a lab environment, the evaluation

board includes op amps to convert single-ended I and Q

input signals to differential . The op amp configuration has

a voltage gain of two; therefore the peak baseband input

voltage should be halved to maintain the same RF output

power. The op amp configuration shown will maintain

acceptable differential balance up to 10MHz typically. It is

also possible to bypass the op amps and drive the

modulator’s differential inputs directly by connecting to

the four oversized vias on the board (V1, V2, V3 and V4).

Figure 6 also shows a table of matching network values for

designs centered at 1.9GHz and1.2GHz.

Figure 7 shows the evaluation board with connectors and

ICs. Figure 8 shows the test set-up with the upconverting

mixer and IQ modulator connected in a transmit configu-

ration. Refer to the demo board

DC365A Quick Start Guide

for detailed testing information.

RF Layout Tips:

• Use 50Ω impedance transmission lines up to the

matching networks, use of a ground plane is a must.

• Keep the matching networks as close to the pins as

possible.

• Surface mount 0402 outline (or smaller) parts are

recommended to minimize parasitic inductances and

capacitances.

• Isolate the MODOUT pin from the LO2 input by putting

the LO2 transmission line on the bottom side of the

board.

• The only ground connection is through the exposed pad

on the bottom of the package. This exposed pad must

be soldered to the board in such a way to get complete

RF contact.

• Low impedance RF ground connections are essential

and can only be obtained by one or more vias tying

directly into the ground plane.

•V

lines must be decoupled with low impedance,

broadband capacitors to prevent instability.

• Separate power supply lines should be used to isolate

the MODIN signal and other stray signals from the

MODOUT line. If possible, power planes should be

used.

• Avoid use of long traces whenever possible. Long RF

traces in particular can lead to signal radiation and

degraded isolation, as well as higher losses.

LT5503

5503f

Figure 6. Evaluation Circuit Schematic for 1.2GHz, 1.9GHz and 2.4GHz Applications

LO1IN LO2IN

5503 F06

234

*C9

MIXER

OUT T1

BQ–

BQ+

GC1

MODIN

VCCMOD

VCCRF

LO1

VCCLO1

DMODE

MX+

BI–

BI+

GC2

MODOUT

VCCVGA

VCCLO2

LO2

MODEN

MIXEN

MX–

*C5 *C6

*C10

C20

1000pF

C18

1μF

*L6

*L5

C41

1μF

OPT

C42

1μF

OPT

C39

4.7μF

C17

1μF

C33

4.7μFC27

0.01μF

C32

4.7μF

C22

1000pF

2.2pF *C7 C19

0.01μF

*C23

*C2

C14

100pF

*C3

MODRFIN

MODRFOUT

*C11

C12

1000pF

C21

0.01μF

C13

8.2pF

*C4

VCC2

VCC3

VCC2

VCC1

VCC4

VCC1

*L3

*L4

47Ω

*R1

*L1

*L2

C45

0.1μF

C24

4.7μF

C43

8.2pF

2.7k

20k

V2 V4

GND

J1 J4

LT5503

–

56Ω

R25

49.9Ω

R21

10k

R23

10k

R13

510Ω

C34

4.7μF

R12

56Ω

R16

510Ω

R15

510Ω

R14

510Ω

7 7

8 8

U2-1

LT1807

U2-2

LT1807

U3-1

LT1807

U3-2

LT1807

4 4

2 2

3 3

1 1

C35, 39pF C36, 39pF

C38, 1pF

C37, 1pF

R19

510Ω

R26

49.9Ω

R27

49.9Ω

R17

510Ω

C40

4.7μF

C15

1μF

C16

1μFR28

49.9Ω

R18

510Ω

R20

510Ω

1% R22

10k

C29

0.01μF

C28

4.7μF

R24

10k

SW1

Q-IN

R29

10Ω

I-IN

*Application Dependent Component Values

1.2GHz Matching

(Modulator Only) 1.9GHz Matching 2.4GHz Matching

L1 33nH 22nH 18nH

L2 12nH 5.6nH 2.7nH

L3 12nH 4.7nH 2.7nH

C2, C3, C7 39pF 15pF 8.2pF

C10 2.7pF 1.8pF 1.2pF

C23 n/a 1.5pF 1.5pF

R1 240Ω390Ω390Ω

C4 n/a 15pF 8.2pF

C5, C6 n/a 1.8pF 2.2pF

C9 n/a 15pF 2.7pF

C11 n/a 2.2pF 1.2pF

L4 n/a 6.8nH 4.7nH

L5,L6 n/a 5.6nH 2.2nH

T1 n/a LDB211G9010C-001 LDB212G4005C-001

APPLICATIO S I FOR ATIO

WUUU

LT5503

5503f

Figure 7. LT5503 Evaluation Board Layout

QIN IIN

GND

VCC4

VCC2 VCC3

VCC1

V2 V1

V3 V4

LT1807 LT1807

LT5503

MODRFIN

LO1IN

MODRFOUT

LO2IN

MIXRFOUT

5503 F07

APPLICATIO S I FOR ATIO

WUUU

LT5503

5503f

Figure 8. Test Set-Up for Upconverting Mixer and

I/Q Modulator Transmit Chain Measurements.

QIN IIN

GND

GND VCC2 VCC3

VCC4

V2 V1 V3 V4

LT1807 LT1807

LT5503

MODRFIN

LO1IN

MODRFOUT

LO2IN

MIXRFOUT

5503 F08

–

90°

0°

DUAL SIGNAL

GENERATOR

SIGNAL

GENERATOR 1

SIGNAL

GENERATOR 1

POWER SUPPLY 2

POWER SUPPLY 3

POWER SUPPLY 1

POWER SUPPLY 4

SPECTRUM

ANALYZER

EXTERNAL 3dB

ATTENUATOR PAD,

OR 2.45GHz BPF

APPLICATIO S I FOR ATIO

WUUU

Information furnished by Linear Technology Corporation is believed to be accurate and reliable.

However, no responsibility is assumed for its use. Linear Technology Corporation makes no represen-

tation that the interconnection of its circuits as described herein will not infringe on existing patent rights.

LT5503

5503f

Linear Technology Corporation

1630 McCarthy Blvd., Milpitas, CA 95035-7417

(408) 432-1900

●

FAX: (408) 434-0507

●

www.linear.com

LT 1107 • PRINTED IN USA

RELATED PARTS

PART NUMBER DESCRIPTION COMMENTS

LT5500 RF Front End Dual LNA Gain Setting +13.5dB/–14dB at 2.5GHz, Double-Balanced Mixer,

1.8V ≤ V

SUPPLY

≤ 5.25V

LT5502 400MHz Quadrature Demodulator with RSSI 1.8V to 5.25V Supply, 70MHz to 400MHz IF, 84dB Limiting Gain, 90dB RSSI Range

LT5504 800MHz to 2.7GHz RF Measuring Reciever 80dB Dynamic Range, Temperature Compensated, 2.7V to 5.5V Supply

LT5505 300MHz to 3.5GHz RF Power Detector >40dB Dynamic Range, Temperature Compensated, 2.7V to 6V Supply

LT5506 500MHz Quadrature IF Demodulator with VGA 1.8V to 5.25V Supply, 40MHz to 500MHz IF, –4dB to 57dB Linear Power Gain

LTC5507 100kHz to 1GHz RF Power Detector 48dB Dynamic Range, Temperature Compensated, 2.7V to 6V Supply

LTC5508 300MHz to 7GHz RF Power Detector SC70 Package

LTC5509 300MHz to 3GHz RF Power Detector 36dB Dynamic Range, SC70 Package

LT5511 High Signal Level Up Converting Mixer RF Output to 3GHz, 17dBm IIP3, Integrated LO Buffer

LT5512 High Signal Level Down Converting Mixer DC-3GHz, 20dBm IIP3, Integrated LO Buffer

LT5515 1.5GHz to 2.5GHz Direct Conversion Demodulator 20dBm IIP3, Integrated LO Quadrature Generator

LT5516 0.8GHz to 1.5GHz Direct Conversion Quadrature 21.5dBm IIP3, Integrated LO Quadrature Generator

Demodulator

LT5522 600MHz to 2.7GHz High Signal Level Mixer 25dBm IIP3 at 900MHz, 21.5dBm IIP3 at 1.9GHz, Matched 50Ω RF and LO Ports,

Integrated LO Buffer

LTC5532 300MHz to 7GHz Precision RF Power Detector Precision V

OUT

Offset Control, Adjustable Gain and Offset Voltage

PACKAGE DESCRIPTIO

FE Package

20-Lead Plastic TSSOP (4.4mm)

(Reference LTC DWG # 05-08-1663)

Exposed Pad Variation CB

FE20 (CB) TSSOP 0204

0.09 – 0.20

(.0035 – .0079)

0° – 8°

0.25

REF

RECOMMENDED SOLDER PAD LAYOUT

0.50 – 0.75

(.020 – .030)

4.30 – 4.50*

(.169 – .177)

134

5678910

111214 13

6.40 – 6.60*

(.252 – .260)

3.86

(.152)

2.74

(.108)

20 1918 17 16 15

1.20

(.047)

MAX

0.05 – 0.15

(.002 – .006)

0.65

(.0256)

BSC 0.195 – 0.30

(.0077 – .0118)

TYP

2.74

(.108)

0.45 ±0.05

0.65 BSC

4.50 ±0.10

6.60 ±0.10

1.05 ±0.10

3.86

(.152)

MILLIMETERS

(INCHES) *DIMENSIONS DO NOT INCLUDE MOLD FLASH. MOLD FLASH

SHALL NOT EXCEED 0.150mm (.006") PER SIDE

NOTE:

1. CONTROLLING DIMENSION: MILLIMETERS

2. DIMENSIONS ARE IN

3. DRAWING NOT TO SCALE

SEE NOTE 4

4. RECOMMENDED MINIMUM PCB METAL SIZE

FOR EXPOSED PAD ATTACHMENT

6.40

(.252)

BSC