100

1k

10k

100k

1M

FREQUENCY (Hz)

10

100

1000

10000

MAX GAIN

MID GAIN

NO GAIN

LMH6502

SNOSA65D – OCTOBER 2003 – REVISED MARCH 2013

www.ti.com

(5)

Figure 60. Output Referred Voltage Noise vs. Frequency

CIRCUIT LAYOUT CONSIDERATIONS & EVALUATION BOARD

A good high frequency PCB layout including ground plane construction and power supply bypassing close to the

package are critical to achieving full performance. The amplifier is sensitive to stray capacitance to ground at the

connections should be treated in a similar fashion. Capacitance to ground should be minimized by removing the

phase margin leading to frequency response peaking.

The LMH6502 is fully stable when driving a 100

Ω load. With reduced load (e.g. 1kΩ) there is a possibility of

instability at very high frequencies beyond 400MHz especially with a capacitive load. When the LMH6502 is

connected to a light load as such, it is recommended to add a snubber network to the output (e.g. 100

Ω and

a small resistor in series with the output (pin 10).

Component parasitics also influence high frequency results. Therefore it is recommended to use metal film

resistors such as RN55D or leadless components such as surface mount devices. High profile sockets are not

recommended.

Texas Instruments suggests the following evaluation boards as a guide for high frequency layout and as an aid in

device testing and characterization:

Device

Package

Evaluation Board Part Number

LMH6502MA

SOIC

LMH730033

18

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