Datasheet

AMP R

OUT

680 nH

390 nH

3 pF

41 pF

27 nH

200

ADC C

200:

3 pF

LMH6514

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SNOSB06A –JANUARY 2008–REVISED MARCH 2013

The output common mode voltage is not self biasing, it needs to be pulled up to the positive supply rail with

external inductors as shown in Figure 42. This gives the LMH6514 the capability for large signal swings with very

low distortion on a single 5V supply. The internal load resistors provide the LMH6514 with very consistent gain.

A unique internal architecture allows the LMH6514 to be driven by either a differential or single ended source. If

driving the LMH6514 single ended the unused input should be terminated to ground with a 0.01 µF capacitor.

Directly shorting the unused input to ground will disrupt the internal bias circuitry and will result in poor

performance.

Center Frequency is 140 MHz with a 20 MHz Bandwidth

Designed for 200Ω Impedance

Figure 50. Bandpass Filter

ADC Noise Filter

Below is a filter schematic and a table of values for some common IF frequencies. The filter shown below offers

a good compromise between bandwidth, noise rejection and cost. This filter topology is the same as is used on

the ADC14V155KDRB High IF Receiver reference design board. This filter topology works best with the 12 and

14 bit sub-sampling analog to digital converters shown in the Table 2 table.

Table 1. Filter Component Values

Filter Component Values

Fc 75 MHz 140 MHz 170 MHz 250 MHz

BW 40 MHz 20 MHz 25 MHz Narrow Band

Components L1, L2 10 µH 10 µH 10 µH 10 µH

L3, L4 390 nH 39 0nH 560 nH —

C1, C2 10 pF 3 pF 1.4 pF 47 pF

C3 22 pF 41 pF 32 pF 11 pF

L5 220 nH 27 nH 30 nH 22 nH

R1, R2 100 200 100 499

Product Folder Links: LMH6514