Datasheet

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LTC6400-26

640026fa

FREQUENCY (MHz)

OUTPUT IP3 (dBm)

100 150 200

640026 TA01b

250 300

NO R

= 200Ω

DIFFERENTIAL INPUT

(NOTE 7)

FEATURES

APPLICATIONS

DESCRIPTION

1.9GHz Low Noise,

Low Distortion Differential

ADC Driver for DC-300MHz

The LTC

6400-26 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 LTC6400-26 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 of transformers or AC-coupling ca-

pacitors in many applications. The gain is internally ﬁ xed

at 26dB (20V/V).

The LTC6400-26 saves space and power compared to

alternative solutions using IF gain blocks and transform-

ers. The LTC6400-26 is packaged in a compact 16-lead

3mm × 3mm QFN package and operates over the –40°C

to 85°C temperature range.

Equivalent OIP3 vs Frequency

■

1.9GHz –3dB Bandwidth

■

Fixed Gain of 20V/V (26dB)

■

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

■

–71dBc IMD3 at 300MHz (Equivalent OIP3 = 39.5dBm)

■

1nV/√Hz Internal Op Amp Noise

■

1.5nV/√Hz Total Input Referred Noise

■

6.8dB Noise Figure

■

Differential Inputs and Outputs

■

50Ω Input Impedance

■

2.85V to 3.5V Supply Voltage

■

85mA Supply Current (255mW)

■

1V to 1.6V Output Common Mode, Adjustable

■

DC- or AC-Coupled Operation

■

Max Differential Output Swing 4.7V

P-P

■

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

■

Differential ADC Driver

■

Differential Driver/Receiver

■

Single Ended to Differential Conversion

■

IF Sampling Receivers

■

SAW Filter Interfacing

37.4Ω

150W

0.1μF

640026 TA01a

LTC6400-26

LTC2208

15Ω

0.1μF

1000pF

3.3V3.3V

15Ω

10Ω

100Ω

OCM

0.1μF

33pF

COILCRAFT

0603CS

1.25V

33pF24nH

33pF

–IN

+IN

+OUT

–OUT

–

AIN

–

LTC2208

130Msps

16-BIT ADC

Single-Ended to Differential ADC Driver at 140MHz IF

TYPICAL APPLICATION

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

All other trademarks are the property of their respective owners.

Summary of content (16 pages)

PAGE 1
LTC6400-26 1.9GHz Low Noise, Low Distortion Differential ADC Driver for DC-300MHz FEATURES ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ DESCRIPTION The LTC®6400-26 is a high-speed differential ampliﬁer targeted at processing signals from DC to 300MHz. The part has been speciﬁcally 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. 1.
PAGE 2
LTC6400-26 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 Speciﬁed Temperature Range (Note 4) ............................................... –40°C to 85°C Storage Temperature Range................... –65°C to 150°C Maximum Junction Temperature....................
PAGE 3
LTC6400-26 DC ELECTRICAL CHARACTERISTICS + The ● –denotes the speciﬁcations which apply over the full operating temperature range, otherwise speciﬁcations are at TA = 25°C. V = 3V, V = 0V, +IN = –IN = VOCM = 1.25V, ENABLE= 0V, No RL unless otherwise noted. SYMBOL PARAMETER CONDITIONS MIN TYP MAX 26 27 UNITS Input/Output Characteristic (+IN, –IN, +OUT, –OUT, +OUTF, –OUTF) GDIFF Gain VIN = ±50mV Differential ● TCGAIN Gain Temperature Drift VIN = ±50mV Differential ● 0.
PAGE 4
LTC6400-26 AC ELECTRICAL CHARACTERISTICS ENABLE = 0V, No RL unless otherwise noted. Speciﬁcations are at TA = 25°C. V+ = 3V, V– = 0V, VOCM = 1.25V, SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS –3dBBW –3dB Bandwidth 200mVP-P,OUT (Note 6) 1.2 1.9 GHz 0.5dBBW Bandwidth for 0.5dB Flatness 200mVP-P,OUT (Note 6) 0.53 GHz 0.1dBBW Bandwidth for 0.1dB Flatness 200mVP-P,OUT (Note 6) 0.28 GHz 1/f 1/f Noise Corner 13.
PAGE 5
LTC6400-26 AC ELECTRICAL CHARACTERISTICS ENABLE = 0V, No RL unless otherwise noted. Speciﬁcations are at TA = 25°C. V+ = 3V, V– = 0V, VOCM = 1.25V, SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS P1dB,140M 1dB Compression Point RL = 375Ω (Notes 5, 7) 18.7 NF140M Noise Figure RL = 375Ω (Note 5) 6.6 dB eN,140M Input Referred Voltage Noise Density Includes Resistors (Short Inputs) 1.
PAGE 6
LTC6400-26 TYPICAL PERFORMANCE CHARACTERISTICS Frequency Response Gain 0.1dB Flatness 30 1.0 0.8 25 GAIN FLATNESS (dB) 0.6 GAIN (dB) 20 15 10 0.2 0 –0.2 –0.4 –0.6 5 0 0.4 –0.8 TEST CIRCUIT B 100 1000 FREQUENCY (MHz) 10 –1.0 3000 10 100 FREQUENCY (MHz) 640026 G01 640026 G02 Input and Output Reﬂection and Reverse Isoloation vs Frequency S21 Phase and Group Delay vs Frequency 0 1000 2000 TEST CIRCUIT B 0 0.8 GROUP DELAY 0.6 –100 0.
PAGE 7
LTC6400-26 TYPICAL PERFORMANCE CHARACTERISTICS Small Signal Transient Response 2.5 9 2.0 EN 8 1.5 7 1.0 NOISE FIGURE 6 5 10 0.5 1.35 OUTPUT VOLTAGE (V) 10 INPUT REFERRED NOISE VOLTAGE (nV/√Hz) NOISE FIGURE (dB) Noise Figure and Input Referred Noise Voltage vs Frequency 0 1000 100 FREQUENCY (MHz) RL = 87.5W PER OUTPUT TEST CIRCUIT B –OUT 1.30 1.25 +OUT 1.20 1.15 2 0 6 4 TIME (ns) 8 640026 G07 640026 G08 Large Signal Transient Response 2.5 Overdriven Transient Response 2.
PAGE 8
LTC6400-26 TYPICAL PERFORMANCE CHARACTERISTICS Third Order Intermodulation Distortion vs Frequency HARMONIC DISTORTION (dBc) –50 THIRD ORDER IMD (dBc) –40 DIFFERENTIAL INPUT VOUT = 2VP-P COMPOSITE –60 –70 –80 –90 –100 –110 0 50 200 150 100 FREQUENCY (MHz) 250 –50 –70 –80 –90 –110 300 HD2 NO RL HD2 RL = 200Ω HD3 NO RL HD3 RL = 200Ω 0 50 200 150 100 FREQUENCY (MHz) 250 640026 G13 –70 –80 –90 –100 300 –110 NO RL RL = 200Ω 0 OUTPUT IP3 (dBm) 17 16 DIFFERENTIAL INPUT (NOTE 7) 40 30 2
PAGE 9
LTC6400-26 PIN FUNCTIONS V+ (Pins 1, 3, 10): Positive Power Supply (Normally tied to 3V or 3.3V). All three pins must be tied to the same voltage. Bypass each pin with 1000pF and 0.1μF capacitors as close to the pins as possible. VOCM (Pin 2): This pin sets the output common mode voltage. An 0.1μF external bypass capacitor is recommended. V– (Pins 4, 9, 12, 17): Negative Power Supply. All four pins must be connected to same voltage/ground. –OUT, +OUT (Pins 5, 8): Unﬁltered Outputs.
PAGE 10
LTC6400-26 APPLICATIONS INFORMATION • Operation from DC to 1.9GHz –3dB bandwidth • Fixed gain of 20V/V (26dB) • Differential input impedance 50Ω • Differential output impedance 25Ω • Differential impedance of output ﬁlter 100Ω The LTC6400-26 is composed of a fully differential ampliﬁer with on chip feedback and output common mode voltage control circuitry. Differential gain and input impedance are set by 25Ω/500Ω resistors in the feedback network. Small output resistors of 12.
PAGE 11
LTC6400-26 APPLICATIONS INFORMATION RS 50Ω VIN + – LTC6400-26 0.1μF 500Ω 25Ω 12.5Ω 13 +IN RT 150Ω +OUT 8 50Ω IN+ OUT– +OUTF 7 14 +IN 50Ω 15 –IN 0.1μF IN– 2.7pF –OUTF 6 OUT+ 500Ω 25Ω 12.5Ω 16 –IN –OUT 5 37.4Ω 640026 F03 The internal low pass ﬁlter outputs at +OUTF/–OUTF have a –3dB bandwidth of 590MHz. External capacitor can reduce the low pass ﬁlter bandwidth as shown in Figure 5. A bandpass ﬁlter is easily implemented with only a few components as shown in Figure 6.
PAGE 12
LTC6400-26 APPLICATIONS INFORMATION –40 LTC6400-26 12.5Ω 500Ω 25Ω 13 +IN SINGLE-ENDED INPUT FS = 122.8Msps –50 DRIVER VOUT = 2VP-P COMPOSITE 39pF 10Ω 4.99Ω –60 +OUT 8 50Ω IN+ –70 OUT– +OUTF 7 14 +IN 15 –IN IN– OUT+ 500Ω 25Ω 16nH 1.7pF 50Ω 39pF LTC2208 –80 –90 –OUTF 6 12.5Ω 16 –IN 10Ω –OUT 5 640026 F06 –100 4.99Ω –110 39pF 0 50 200 150 100 FREQUENCY (MHz) 250 300 640026 F08 Figure 6.
PAGE 13
LTC6400-26 TYPICAL APPLICATION Demo Circuit 987B Schematic (Test Circuit A) VCC ENABLE 1 3 DIS 2 JP1 VCC C17 1000pF R16 0W 12 V– R2 (1) T1 (2) R5 0dB (1) 1 • • 5 4 R4 (2) 2 3 C21 0.1μF R3 (2) C2 0.1μF 14 R24 (1) SL1 (2) 16 R1 0Ω +IN +OUTF –IN –OUTF –IN –OUT V+ VOCM 1 VCC R10 86.6Ω 7 R8 (1) C10 0.1μF V+ 2 6 5 R14 (1) C4 0.1μF SL2 (2) R7 (1) C3 0.1μF R9 86.6Ω V– 3 4 C9 1000pF T2 TCM 4:19 1:4 4 R12 0Ω 1 6 R11 (1) C22 0.
PAGE 14
LTC6400-26 TYPICAL APPLICATIONS Test Circuit B, 4-Port Analysis V+ 0.1μF 1000pF 12 V– 11 ENABLE 10 V+ 9 V– BIAS CONTROL 24.9Ω PORT 1 (50Ω) RF 500Ω RG 25Ω +IN 13 ROUT 12.5Ω RFILT 50Ω 0.1μF +IN 14 1/2 AGILENT E5O71A IN+ 24.9Ω PORT 3 (50Ω) +OUTF IN– CFILT 2.7pF 1/2 AGILENT E5O71A –OUTF 6 OUT+ RF 500Ω RG 25Ω –IN 16 0.1μF 7 OUT– RFILT 50Ω –IN 15 PORT 2 (50Ω) +OUT 37.4Ω 8 ROUT 12.5Ω –OUT 37.4Ω PORT 4 (50Ω) 5 0.1μF 0.1μF COMMON MODE CONTROL 1 2 V+ 3 VOCM 0.
PAGE 15
LTC6400-26 PACKAGE DESCRIPTION UD Package 16-Lead Plastic QFN (3mm × 3mm) (Reference LTC DWG # 05-08-1691) 0.70 p 0.05 3.50 p 0.05 1.45 p 0.05 2.10 p 0.05 (4 SIDES) PACKAGE OUTLINE 0.25 p 0.05 0.50 BSC RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS 3.00 p 0.10 (4 SIDES) BOTTOM VIEW—EXPOSED PAD PIN 1 NOTCH R = 0.20 TYP OR 0.25 s 45o CHAMFER R = 0.115 TYP 0.75 p 0.05 15 16 PIN 1 TOP MARK (NOTE 6) 0.40 p 0.10 1 1.45 p 0.10 (4-SIDES) 2 (UD16) QFN 0904 0.200 REF 0.00 – 0.05 NOTE: 1.
PAGE 16
LTC6400-26 RELATED PARTS PART NUMBER DESCRIPTION COMMENTS High-Speed Differential Ampliﬁers/Differential Op Amps LT®1993-2 800MHz Differential Ampliﬁer/ADC Driver AV = 2V/V, OIP3 = 38dBm at 70MHz LT1993-4 900MHz Differential Ampliﬁer/ADC Driver AV = 4V/V, OIP3 = 40dBm at 70MHz LT1993-10 700MHz Differential Ampliﬁer/ADC Driver AV = 2V/V, OIP3 = 40dBm at 70MHz LT1994 Low Noise, Low Distortion Differential Op Amp 16-Bit SNR and SFDR at 1MHz, Rail-to-Rail Outputs LT5514 Ultralow Distortion IF Am