Linear LTC6400-20 Schematic [ru]

LTC6400-20

1.8GHz Low Noise, Low

Distortion Differential ADC

Driver for 300MHz IF

FEATURES

■

1.8GHz –3dB Bandwidth

■

Fixed Gain of 10V/V (20dB)

■

–94dBc IMD3 at 70MHz (Equivalent OIP3 = 51dBm)

■

–65dBc IMD3 at 300MHz (Equivalent OIP3 = 36.5dBm)

■

1nV/√Hz Internal Op Amp Noise

■

2.1nV/√Hz Total Input Noise

■

6.2dB Noise Figure

■

Differential Inputs and Outputs

■

200Ω Input Impedance

■

2.85V to 3.5V Supply Voltage

■

90mA Supply Current (270mW)

■

1V to 1.6V Output Common Mode Voltage,

Adjustable

■

DC- or AC-Coupled Operation

■

Max Differential Output Swing 4.4V

■

Small 16-Lead 3mm × 3mm × 0.75mm QFN Package

P-P

APPLICATIONS

■

Differential ADC Driver

■

Differential Driver/Receiver

■

Single Ended to Differential Conversion

■

IF Sampling Receivers

■

SAW Filter Interfacing

DESCRIPTION

The LTC®6400-20 is a high-speed differential amplifi er
targeted at processing signals from DC to 300MHz. The
part has been specifi cally designed to drive 12-, 14- and
16-bit ADCs with low noise and low distortion, but can also
be used as a general-purpose broadband gain block.

The LTC6400-20 is easy to use, with minimal support
circuitry required. The output common mode voltage is
set using an external pin, independent of the inputs, which
eliminates the need for transformers or AC-coupling ca­pacitors in many applications. The gain is internally fi xed
at 20dB (10V/V).

The LTC6400-20 saves space and power compared to
alternative solutions using IF gain blocks and transform­ers. The LTC6400-20 is packaged in a compact 16-lead
3mm × 3mm QFN package and operates over the –40°C
to 85°C temperature range.

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

All other trademarks are the property of their respective owners.

TYPICAL APPLICATION

Single-Ended to Differential ADC Driver

0.1μF

INPUT

66.5Ω

1000pF

29Ω

0.1μF

0.1μF

+

V

V

OCM

+IN

LTC6400-20

–IN

ENABLE

–

V

+OUT

+OUTF

–OUTF

–OUT

20dB GAIN

1.25V

10Ω

10Ω

3.3V

VCMV

+

AIN

LTC2208

–

AIN

LTC2208 130Msps

16-Bit ADC

DD

640020 TA01a

0.1μF

Equivalent Output IP3 vs

60

50

40

30

20

OUTPUT IP3 (dBm)

10

0

050

Frequency

100 150 200
FREQUENCY (MHz)

(NOTE 7)

250 300

640020 TA01b

640020f

1

LTC6400-20

ABSOLUTE MAXIMUM RATINGS

PIN CONFIGURATION

(Note 1)

Supply Voltage (V+ – V–) ..........................................3.6V

Input Current (Note 2) ..........................................±10mA

Operating Temperature Range

(Note 3) ...............................................–40°C to 85°C

Specifi ed Temperature Range

(Note 4) ...............................................–40°C to 85°C

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

Maximum Junction Temperature .......................... 150°C

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

V

OCM

V

V

16-LEAD (3mm × 3mm) PLASTIC QFN

T

JMAX

EXPOSED PAD (PIN 17) IS V

TOP VIEW

–IN

–IN

+IN

+IN

16 15 14 13

+

1V

2

3

4

5 6 7 8

–OUT

UD PACKAGE

17

–OUTF

+OUTF

–

, MUST BE SOLDERED TO PCB

+

–

= 125°C, θJA = 68°C/W, θJC = 4.2°C/W

12

11

10

+OUT

9

–

V

ENABLE

+

V

–

V

ORDER INFORMATION

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

LTC6400CUD-20#PBF LTC6400CUD-20#TRPBF LCCS 16-Lead (3mm × 3mm) Plastic QFN 0°C to 70°C
LTC6400IUD-20#PBF LTC6400IUD-20#TRPBF LCCS 16-Lead (3mm × 3mm) Plastic QFN –40°C to 85°C
Consult LTC Marketing for parts specifi ed with wider operating temperature ranges. *The temperature grade is identifi ed by a label on the shipping container.

Consult LTC Marketing for information on non-standard lead based fi nish parts.
For more information on lead free part marking, go to: http://www.linear.com/leadfree/

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

LTC6400 AND LTC6401 SELECTOR GUIDE

PART NUMBER GAIN

(dB)

GAIN
(V/V)

Please check each datasheet for complete details.

ZIN (DIFFERENTIAL)

(Ω)

I

S

(mA)

LTC6400-20 20 10 200 90
LTC6401-20 20 10 200 50

In addition to the LTC6400 family of amplifi ers, a lower power LTC6401 family is available. The LTC6401 is pin compatible to the LTC6400, and has the
same low noise performance. The lower power consumption of the LTC6401 comes at the expense of slightly higher non-linearity, especially at input
frequencies above 140MHz. Please refer to the separate LTC6401 data sheets for complete details. Other gain versions from 8dB to 26dB will follow.

640020f

2

LTC6400-20

DC ELECTRICAL CHARACTERISTICS

The ● denotes the specifi cations which apply over the full operating
temperature range, otherwise specifi cations are at T

= 25°C. V+ = 3V, V– = 0V, +IN = –IN = V

A

otherwise noted.

SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS

Input/Output Characteristic

G

DIFF

TC

GAIN

V

SWINGMIN

V

SWINGMAX

V

OUTDIFFMAX

I

OUT

V

OSDIFF

TCV

OSDIFF

I

VRMIN

I

VRMAX

R

INDIFF

C

INDIFF

R

OUTDIFF

R

OUTFDIFF

C

OUTFDIFF

CMRR Common Mode Rejection Ratio Input Common Mode Voltage 1.1V~1.4V

Output Common Mode Voltage Control

G

CM

V

OCMMIN

V

OCMMAX

V

OSCM

TCV

OSCM

IV

OCM

⎯E⎯N⎯A⎯B⎯L⎯

E Pin

V

IL

V

IH

I

IL

I

IH

Power Supply

V

S

I

S

I

SHDN

PSRR Power Supply Rejection Ratio (Differential

Gain VIN = ±100mV Differential
Gain Temperature Drift VIN = ±100mV Differential
Output Swing Low Each Output, VIN = ±600mV Differential
Output Swing High Each Output, VIN = ±600mV Differential
Maximum Differential Output Swing 1dB Compressed
Output Current Drive Each Output
Input Differential Offset Voltage
Input Differential Offset Voltage Drift T

MIN

to T

MAX

Input Common Mode Voltage Range, MIN 1 V
Input Common Mode Voltage Range, MAX 1.6 V
Input Resistance (+IN, –IN) Differential
Input Capacitance (+IN, –IN) Differential, Includes Parasitic 1 pF
Output Resistance (+OUT, –OUT) Differential
Filtered Output Resistance (+OUTF, –OUTF) Differential
Filtered Output Capacitance (+OUTF, –OUTF) Differential, Includes Parasitic 2.7 pF

Common Mode Gain V

= 1V to 1.6V 1 V/V

OCM

Output Common Mode Range, MIN

Output Common Mode Range, MAX

Common Mode Offset Voltage V
Common Mode Offset Voltage Drift T
V

Input Current

OCM

⎯E⎯N⎯A⎯B⎯L⎯

E Input Low Voltage

⎯E⎯N⎯A⎯B⎯L⎯

E Input High Voltage

⎯E⎯N⎯A⎯B⎯L⎯

E Input Low Current

⎯E⎯N⎯A⎯B⎯L⎯

E Input High Current

= 1.1V to 1.5V

OCM

to T

MIN

⎯E⎯N⎯A⎯B⎯L⎯

E = 0.8V

⎯E⎯N⎯A⎯B⎯L⎯

E = 2.4V

MAX

Operating Supply Range
Supply Current
Shutdown Supply Current

⎯E⎯N⎯A⎯B⎯L⎯

E = 0.8V

⎯E⎯N⎯A⎯B⎯L⎯

E = 2.4V

+

= 2.85V to 3.5V

V

Outputs)

= 1.25V, ⎯E⎯N⎯A⎯B⎯L⎯E = 0V, No RL unless

OCM

●

19.4 20 20.6 dB

●

●

●

2.35 2.46 V

●

●

20 mA

●

–2 2 mV

●

●

170 200 230

●

18 25 32

●

85 100 115

●

45 65 dB

–1.5 mdB/°C

80 150 mV

4.4 V

1.2 μV/°C

1

●

1.1

1.6

●

1.5

●

–15 15 mV

●

●

●

●

2.4 V

●

●

●

2.85 3 3.5 V

●

75 90 105 mA

●

●

55 86 dB

16 μV/°C

515 μA

0.8 V

0.5 μA

1.2 3 μA

13 mA

P-P

Ω

Ω

Ω

V
V

V
V

640020f

3

LTC6400-20

AC ELECTRICAL CHARACTERISTICS

Specifi cations are at TA = 25°C. V+ = 3V, V– = 0V, V

⎯E⎯N⎯A⎯B⎯L⎯

E = 0V, No RL unless otherwise noted.

SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS

–3dBBW –3dB Bandwidth 200mV

0.1dBBW Bandwidth for 0.1dB Flatness 200mV

0.5dBBW Bandwidth for 0.5dB Flatness 200mV
1/f 1/f Noise Corner 10.5 kHz
SR Slew Rate Differential (Note 6) 4.5 V/ns
t

S1%

t

OVDR

t

ON

t

OFF

–3dBBW

VOCM

1% Settling Time 2V
Overdrive Recovery Time 1.9V

P-P,OUT

P-P,OUT

Turn-On Time +OUT, –OUT Within 10% of Final Values 82 ns
Turn-Off Time ICC Falls to 10% of Nominal 190 ns
V

Pin Small Signal –3dB BW 0.1V

OCM

P-P

Output (Note 6)

10MHz Input Signal

HD

IMD

OIP

2,10M

3,10M

3,10M

/HD

3,10M

Second/Third Order Harmonic
Distortion

Third-Order Intermodulation
(f1 = 9.5MHz f2 = 10.5MHz)

Third-Order Output Intercept Point

2V

P-P,OUT

2V

P-P,OUT

2V

P-P,OUTFILT

2V

P-P,OUT

2V

P-P,OUT

2V

P-P,OUTFILT

2V

P-P,OUT

(f1 = 9.5MHz f2 = 10.5MHz)

P

1dB,10M

NF

10M

e

IN,10M

e

ON,10M

1dB Compression Point RL = 375Ω (Notes 5, 7) 18 dBm
Noise Figure RL = 375Ω (Note 5) 6.2 dB
Input Referred Voltage Noise Density Includes Resistors (Short Inputs) 2.2 nV/√Hz
Output Referred Voltage Noise Density Includes Resistors (Short Inputs) 21.7 nV/√Hz

70MHz Input Signal

HD

IMD

OIP

2,70M

3,70M

3,70M

/HD

3,70M

Second/Third Order Harmonic
Distortion

Third-Order Intermodulation
(f1 = 69.5MHz f2 = 70.5MHz)

Third-Order Output Intercept Point

2V

P-P,OUT

2V

P-P,OUT

2V

P-P,OUTFILT

2V

P-P,OUT

2V

P-P,OUT

2V

P-P,OUTFILT

2V

P-P,OUT

(f1 = 69.5MHz f2 = 70.5MHz)

P

1dB,70M

NF

70M

e

IN,70M

e

ON,70M

1dB Compression Point RL = 375Ω (Notes 5, 7) 18 dBm
Noise Figure RL = 375Ω (Note 5) 6.2 dB
Input Referred Voltage Noise Density Includes Resistors (Short Inputs) 2.1 nV/√Hz
Output Referred Voltage Noise Density Includes Resistors (Short Inputs) 21 nV/√Hz

(Note 6) 1.84 GHz

P-P,OUT

(Note 6) 0.3 GHz

P-P,OUT

(Note 6) 0.7 GHz

P-P,OUT

(Note 6) 0.8 ns

(Note 6) 4 ns

at V

, Measured Single-Ended at

OCM

15 MHz

, RL = 400Ω –97/–93 dBc
, No R

, No R

L

L

–98/–97 dBc

–100/–98 dBc
Composite, RL = 400Ω –95 dBc
Composite, No R

Composite, No R

L

L

–99 dBc

–100 dBc

Composite, No RL (Note 7) 53.8 dBm

, RL = 400Ω –86/–85 dBc
, No R

, No R

L

L

–88/–87 dBc

–86/–88 dBc
Composite, RL = 400Ω –93 dBc
Composite, No R

Composite, No R

L

L

–94 dBc
–93 dBc

Composite, No RL (Note 7) 51 dBm

OCM

= 1.25V,

4

640020f

LTC6400-20

AC ELECTRICAL CHARACTERISTICS

Specifi cations are at TA = 25°C. V+ = 3V, V– = 0V, V

⎯E⎯N⎯A⎯B⎯L⎯

E = 0V, No RL unless otherwise noted.

SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS

140MHz Input Signal

2,140M

3,140M

3,140M

1dB,140M

140M

IN,140M

ON,140M

/HD

HD

IMD

OIP

P
NF
e
e

240MHz Input Signal

2,240M

3,240M

3,240M

1dB,240M

240M

N, 240M

ON,240M

/HD

HD

IMD

OIP

P
NF
e
e

Second/Third Order Harmonic

3,140M

Distortion

Third-Order Intermodulation
(f1 = 139.5MHz f2 = 140.5MHz)

Third-Order Output Intercept Point

2V

P-P,OUT

2V

P-P,OUT

2V

P-P,OUTFILT

2V

P-P,OUT

2V

P-P,OUT

2V

P-P,OUTFILT

2V

P-P,OUT

, RL = 400Ω –74/–74 dBc
, No R

, No R

L

L

–73/–83 dBc

–77/–76 dBc
Composite, RL = 400Ω –93 dBc
Composite, No R

Composite, No R

L

L

–87 dBc
–89 dBc

Composite, No RL (Notes 7) 47.7 dBm

(f1 = 139.5MHz f2 = 140.5MHz)
1dB Compression Point RL = 375Ω (Notes 5, 7) 18.4 dBm
Noise Figure RL = 375Ω (Note 5) 6.5 dB
Input Referred Voltage Noise Density Includes Resistors (Short Inputs) 2.1 nV/√Hz
Output Referred Voltage Noise Density Includes Resistors (Short Inputs) 21.5 nV/√Hz

Second-Order Harmonic Distortion 2V

3,240M

Third-Order Intermodulation
(f1 = 239.5MHz f2 = 240.5MHz)

Third-Order Output Intercept Point

2V
2V
2V
2V
2V
2V

, RL = 400Ω –66/–58 dBc

P-P,OUT

, No R

P-P,OUT

P-P,OUTFILT

P-P,OUT

P-P,OUT

P-P,OUTFILT

P-P,OUT

L

, No R

L

Composite, RL = 400Ω –71 dBc
Composite, No R

Composite, No R

L

L

Composite, No RL (Note 7) 41 dBm

–65/–63 dBc

–65/–58 dBc

–74 dBc
–67 dBc

(f1 = 239.5MHz f2 = 240.5MHz)
1dB Compression Point RL = 375Ω (Notes 5, 7) 17.9 dBm
Noise Figure RL = 375Ω (Note 5) 7.1 dB
Input Referred Voltage Noise Density Includes Resistors (Short Inputs) 1.9 nV/√Hz
Output Referred Voltage Noise Density Includes Resistors (Short Inputs) 21.7 nV/√Hz

OCM

= 1.25V,

640020f

5

LTC6400-20

AC ELECTRICAL CHARACTERISTICS

Specifi cations are at TA = 25°C. V+ = 3V, V– = 0V, V

⎯E⎯N⎯A⎯B⎯L⎯

E = 0V, No RL unless otherwise noted.

SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS

300MHz Input Signal

HD

2,300M

IMD

3,300M

OIP

3,300M

P

1dB,300M

NF

300M

e

N,300M

e

ON,300M

IMD

3,280M/320M

/HD

Second-Order Harmonic Distortion 2V

3,300M

Third-Order Intermodulation
(f1 = 299.5MHz f2 = 300.5MHz)

Third-Order Output Intercept Point

2V
2V
2V
2V
2V
2V

, RL = 400Ω –61/–53 dBc

P-P,OUT

, No R

P-P,OUT

P-P,OUTFILT

P-P,OUT

P-P,OUT

P-P,OUTFILT

P-P,OUT

L

, No R

L

Composite, RL = 400Ω –64 dBc
Composite, No R

Composite, No R

L

L

Composite, No RL (Note 7) 36.6 dBm

–60/–55 dBc

–63/–46 dBc

–65 dBc
–58 dBc

(f1 = 299.5MHz f2 = 300.5MHz)
1dB Compression Point RL = 375Ω (Notes 5, 7) 17.5 dBm
Noise Figure RL = 375Ω (Note 5) 7.5 dB
Input Referred Voltage Noise Density Includes Resistors (Short Inputs) 1.8 nV/√Hz
Output Referred Voltage Noise Density Includes Resistors (Short Inputs) 22 nV/√Hz
Third-Order Intermodulation

2V

Composite, RL = 375Ω –64 –70 dBc

P-P,OUT

(f1 = 280MHz f2 = 320MHz) Measure
at 360MHz

OCM

= 1.25V,

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: Input pins (+IN, –IN) are protected by steering diodes to either
supply. If the inputs go beyond either supply rail, the input current should
be limited to less than 10mA.

Note 3: The LTC6400C and LTC6400I are guaranteed functional over the
operating temperature range of –40°C to 85°C.

Note 4: The LTC6400C is guaranteed to meet specifi ed performance from
0°C to 70°C. It is designed, characterized and expected to meet specifi ed

performance from –40°C to 85°C but is not tested or QA sampled at these
temperatures. The LTC6400I is guaranteed to meet specifi ed performance
from –40°C to 85°C.

Note 5: Input and output baluns used. See Test Circuit A.
Note 6: Measured using Test Circuit B.
Note 7: Since the LTC6400-20 is a feedback amplifi er with low output

impedance, a resistive load is not required when driving an AD converter.
Therefore, typical output power is very small. In order to compare the
LTC6400-20 with amplifi ers that require 50Ω output load, the LTC6400-20
output voltage swing driving a given R
if it were driving a 50Ω load. Using this modifi ed convention, 2V
defi nition equal to 10dBm, regardless of actual R

is converted to OIP3 and P

L

.

L

P-P

1dB

is by

as

6

640020f