05.01.2015 Views

Op Amps for Everyone - The Repeater Builder's Technical ...

Op Amps for Everyone - The Repeater Builder's Technical ...

Op Amps for Everyone - The Repeater Builder's Technical ...

SHOW MORE
SHOW LESS

You also want an ePaper? Increase the reach of your titles

YUMPU automatically turns print PDFs into web optimized ePapers that Google loves.

<strong>The</strong> Noninverting CFA<br />

+<br />

V IN<br />

G = 1<br />

+<br />

Z B<br />

–<br />

IZ<br />

I<br />

G = 1<br />

V OUT<br />

Z G<br />

V A<br />

Z F<br />

Figure 8–4. Noninverting CFA<br />

Equation 8–6 is the transfer equation, Equation 8–7 is the current equation at the inverting<br />

node, and Equation 8–8 is the input loop equation. <strong>The</strong>se equations are combined to yield<br />

the closed-loop gain equation, Equation 8–9.<br />

V OUT<br />

IZ<br />

I V A<br />

Z G<br />

– V OUT –V A<br />

Z F<br />

(8–6)<br />

(8–7)<br />

V A<br />

V IN<br />

–IZ B<br />

(8–8)<br />

Z1 Z F<br />

Z G<br />

<br />

Z F 1<br />

Z B<br />

V<br />

Z F<br />

Z G<br />

<br />

(8–9)<br />

OUT<br />

<br />

V IN 1 <br />

Z<br />

Z F 1<br />

Z B<br />

Z F<br />

Z G<br />

<br />

When the input buffer output impedance, Z B , approaches zero, Equation 8–9 reduces to<br />

Equation 8–10.<br />

8-4

Hooray! Your file is uploaded and ready to be published.

Saved successfully!

Ooh no, something went wrong!