LMH6555_14 Datasheet, PDF (26/37 Pages) Texas Instruments – LMH6555 Low Distortion 1.2 GHz Differential Driver

LMH6555
SNOSAJ1C – NOVEMBER 2006 – REVISED MARCH 2011
www.ti.com
Figure 42, Figure 43, and Figure 44 information summary:
• Fundamental Test Frequency 744 MHz
• LMH6555 Output 0.8 V_PP
• Sampling Rate: 1.5G samples/second
• 2nd Harmonic: −59 dBc @ ∼ 12 MHz or |1.5 GHz*1– 744 MHz*2|
• 3rd Harmonic: −57 dBc @ ∼ 732 MHz or |1.5 GHz*1- 744 MHz *3|
• 4th Harmonic −71 dBc @ ∼ 24 MHz or |1.5 GHz*2 – 744 MHz *4|
• 5th Harmonic −68 dBc @ ∼ 720 MHz or |1.5 GHz*2- 744 MHz*5|
• 6th Harmonic −68 dBc @ ∼ 36 MHz or |1.5 GHz*3- 744 MHz*6|
• THD −51.8 dBc
• SNR 43.4 dB
• Spurious Free Dynamic
• Range (SFDR): 57 dB
• SINAD 42.8 dB
• ENOB 6.8 bits
The LMH6555 is capable of driving a variety of National Semiconductor Analog to Digital Converters. This is
shown in Table 2, which offers a complete list of possible signal path ADC+ Amplifier combinations. The use of
the LMH6555 to drive an ADC is determined by the application and the desired sampling process (Nyquist
operation, sub-sampling or over-sampling). See application note (AN-236) for more details on the sampling
processes and application note (AN-1393) for details on “Using High Speed Differential Amplifiers to Drive
ADCs”. For more information regarding a particular ADC, refer to the particular ADC datasheet for details.
Table 2. Differential Input ADC’s Compatible with the LMH6555 Driver
ADC Part Number
ADC08D500
ADC081000
ADC08D1000
ADC08D1020
ADC081500
ADC08D1500
ADC08D1520
ADC083000
ADC08B3000
Resolution (bits)
8
8
8
8
8
8
8
8
8
Single/Dual
S
S
D
D
S
D
D
S
S
Speed (MSPS)
500
1000
1000
1000
1500
1500
1500
3000
3000
EXPOSED PAD WQFN PACKAGE
The LMH6555 is in a thermally enhanced package. The exposed pad (device bottom) is connected to the GND
pins. It is recommended, but not necessary, that the exposed pad be connected to the supply ground plane. The
thermal dissipation of the device is largely dependent on the connection of this pad. The exposed pad should be
attached to as much copper on the circuit board as possible, preferably external copper. However, it is very
important to maintain good high speed layout practices when designing a system board.
Here is a link to more information on the Texas Instruments 16-pin WQFN package:
http://www.ti.com/packaging
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