Datasheet

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LTC6431-15

643115f

Typical applicaTion

FeaTures DescripTion

Gain Block

IF Amplifier

The LTC

6431-15 is a gain-block amplifier with excellent

linearity at frequencies beyond 1000MHz and with low

associated output noise.

The unique combination of high linearity, low noise and

low power dissipation make this an ideal candidate for

many signal-chain applications. The LTC6431-15 is easy

to use, requiring a minimum of external components. It is

internally input/output matched to 50Ω and it draws only

90mA from a single 5V supply.

On-chip bias and temperature compensation maintain

performance over environmental changes.

The LTC6431-15 uses a high performance SiGe BiCMOS

process for excellent repeatability compared with similar

GaAs amplifiers. All A-grade LTC6431-15 devices are tested

and guaranteed for OIP3 at 240MHz. The LTC6431-15 is

housed in a 4mm × 4mm 24-lead QFN package with an

exposed pad for thermal management and low inductance.

Single-Ended IF Amplifier

OIP3 vs Frequency

applicaTions

20MHz to 1700MHz Bandwidth

15.5dB Power Gain

47dBm OIP3 at 240MHz into a 50Ω Load

NF = 3.33dB at 240MHz

1nV/√Hz Total Input Noise

S11 < –15dB Up to 1.2GHz

S22 < –15dB Up to 1.2GHz

>2V

P-P

Linear Output Swing

P1dB = 20.6dBm

DC Power = 450mW

50Ω Single-Ended Operation

Insensitive to V

Variation

A-Grade 100% OIP3 Tested at 240MHz

Input/Output Internally Matched to 50Ω

Single 5V Supply

Unconditionally Stable

Single-Ended IF Amplifier

ADC Driver

CATV

L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks of Linear

Technology Corporation. All other trademarks are the property of their respective owners.

643115 TA01a

LTC6431-15

SOURCE

50Ω

= 5V

1000pF 1000pF

CHOKE,

560nH

LOAD

50Ω

FREQUENCY (MHz)

OIP3 (dBm)

400 800

200

600 1000

643115 TA01b

= 5V, T = 25°C

OUT

= 2dBm/TONE

SPACE

= 1MHz

= Z

OUT

= 50Ω

Summary of content (16 pages)

PAGE 1
LTC6431-15 50Ω Gain Block IF Amplifier Features n n n n n n n n n n n n n n n n Description 20MHz to 1700MHz Bandwidth 15.5dB Power Gain 47dBm OIP3 at 240MHz into a 50Ω Load NF = 3.33dB at 240MHz 1nV/√Hz Total Input Noise S11 < –15dB Up to 1.2GHz S22 < –15dB Up to 1.2GHz > 2VP-P Linear Output Swing P1dB = 20.
PAGE 2
LTC6431-15 Absolute Maximum Ratings Pin Configuration (Note 1) Total Supply Voltage (VCC to GND)...........................5.5V Amplifier Output Current (OUT)............................105mA RF Input Power, Continuous, 50Ω (Note 2)..........15dBm RF Input Power, 100µs Pulse, 50Ω (Note 2).........20dBm Operating Case Temperature Range (TCASE)...........................................–40°C to 85°C Storage Temperature Range................... –65°C to 150°C Junction Temperature (TJ).......................
PAGE 3
LTC6431-15 AC Electrical Characteristics TA = 25°C (Note 3), VCC = 5V, ZSOURCE = ZLOAD = 50Ω, unless otherwise noted. Measurements are performed using Test Circuit A, measuring from 50Ω SMA to 50Ω SMA without de-embedding (Note 4).
PAGE 4
LTC6431-15 AC Electrical Characteristics TA = 25°C (Note 3), VCC = 5V, ZSOURCE = ZLOAD = 50Ω, unless otherwise noted. Measurements are performed using Test Circuit A, measuring from 50Ω SMA to 50Ω SMA without de-embedding (Note 4).
PAGE 5
LTC6431-15 AC Electrical Characteristics TA = 25°C (Note 3), VCC = 5V, ZSOURCE = ZLOAD = 50Ω, unless otherwise noted. Measurements are performed using Test Circuit A, measuring from 50Ω SMA to 50Ω SMA without de-embedding (Note 4).
PAGE 6
LTC6431-15 Typical Performance Characteristics TA = 25°C, VCC = 5V, ZSOURCE = ZLOAD = 50Ω, unless otherwise noted. Measurements are performed using Test Circuit A, measuring from 50Ω SMA to 50Ω SMA without de-embedding (Note 4).
PAGE 7
LTC6431-15 Typical Performance Characteristics A-Grade TA = 25°C, VCC = 5V, ZSOURCE = ZLOAD = 50Ω, unless otherwise noted. Measurements are performed using Test Circuit A, measuring from 50Ω SMA to 50Ω SMA without de-embedding (Note 4).
PAGE 8
LTC6431-15 Typical Performance Characteristics TA = 25°C, VCC = 5V, ZSOURCE = ZLOAD = 50Ω, unless otherwise noted. Measurements are performed using Test Circuit A, measuring from 50Ω SMA to 50Ω SMA without de-embedding (Note 4).
PAGE 9
LTC6431-15 Pin Functions GND (Pins 8, 17, 23, Exposed Pad Pin 25): Ground. For best RF performance, all ground pins should be connected to the printed circuit board ground plane. The exposed pad should have multiple via holes to an underlying ground plane for low inductance and good thermal dissipation. IN (Pin 24): Signal Input Pin. This pin has an internally generated 2V DC bias. A DC blocking capacitor is required. See the Applications Information section for specific recommendations.
PAGE 10
LTC6431-15 Test Circuit A C1 60pF C5 1nF C6 0.1µF OPTIONAL STABILITY NETWORK L1 560nH DNC DNC IN R1 350Ω DNC VCC = 5V VCC C7 1000pF GND PORT INPUT DNC OUT DNC GND DNC T_DIODE DNC DNC DNC DNC DNC VCC GND DNC DNC PORT OUTPUT DNC LTC6431-15 DNC C3 1000pF DNC 643115 F01 Figure 1. Application, Test Circuit A Operation The LTC6431-15 is a highly linear, fixed-gain amplifier that is configured to operate single ended.
PAGE 11
LTC6431-15 Applications Information The LTC6431-15 is a highly linear fixed-gain amplifier which is designed for ease of use. Implementing an RF gain stage is often a multistep project. Typically an RF designer must choose a bias point and design a bias network. Next the designer needs to address impedance matching with input and output matching networks and, finally, add stability networks to ensure stable operation in and out of band. These tasks are handled internally within the LTC6431-15.
PAGE 12
LTC6431-15 Applications Information Low Frequency Stability Most RF gain blocks suffer from low frequency instability. To avoid any stability issues, the LTC6431-15 has an internal feedback network that lowers the gain and matches the input and output impedances at frequencies above 20MHz. This feedback network contains a series capacitor, so if at some low frequency the feedback fails, the gain increases and gross impedance mismatches occur—indeed a recipe for instability.
PAGE 13
LTC6431-15 Applications Information 5 4 6 C17 1000pF 1 DATE 08-18-11 CAL OUT 2 4 6 8 3 5 7 C7 VCC 1000pF C8 62pF 1 SMA-R JP2 HD2X4-100 OPT VCC R2 348 C 3 4 5 6 7 8 9 10 DNC 21 DNC 20 DNC 19 U1 *1 +OUT 18 GND 17 DNC 2 DNC 3 DNC C21 1000pF J10 C3 1000pF * +OUT SMA-R GND 14 DNC 13 6 DNC DNC 25 7 C22 0.
PAGE 14
LTC6431-15 S Parameters 5V, 90mA, Z = 50Ω, T = 25°C, De-Embedded to Package Pins FREQUENCY (MHz) S11 (Mag) S11 (Ph) S21 (Mag) S21 (Ph) S12 (Mag) S12 (Ph) S22 (Mag) S22 (Ph) GTU (Max) Stability (K) 23.5 –14.90 –93.74 15.94 166.13 –19.01 8.83 –15.39 –77.56 16.21 0.99 83.5 –21.83 –128.88 15.54 169.51 –18.92 –3.42 –26.58 –72.76 15.58 1.07 143 –22.33 –142.38 15.54 166.10 –18.98 –8.97 –31.71 –52.44 15.57 1.07 203 –22.14 –153.70 15.54 161.63 –19.04 –13.69 –36.
PAGE 15
LTC6431-15 Package Description Please refer to http://www.linear.com/designtools/packaging/ for the most recent package drawings. UF Package 24-Lead Plastic QFN (4mm × 4mm) (Reference LTC DWG # 05-08-1697 Rev B) 0.70 ±0.05 4.50 ±0.05 2.45 ±0.05 3.10 ±0.05 (4 SIDES) PACKAGE OUTLINE 0.25 ±0.05 0.50 BSC RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS 4.00 ±0.10 (4 SIDES) BOTTOM VIEW—EXPOSED PAD R = 0.115 TYP 0.75 ±0.05 PIN 1 NOTCH R = 0.20 TYP OR 0.35 × 45° CHAMFER 23 24 PIN 1 TOP MARK (NOTE 6) 0.
PAGE 16
LTC6431-15 Typical Application VCC = 5V RSOURCE 50Ω 0.1µF 5V RF CHOKE, L = 560nH 9, 22 C = 1000pF 24 LTC6431-15 1000pF C =1000pF 18 RLOAD 50Ω 8, 17, 23, 25 643115 TA02 Related Parts PART NUMBER DESCRIPTION COMMENTS Fixed Gain IF Amplifiers/ADC Drivers LTC6417 1.