<html><head><meta http-equiv="Content-Type" content="text/html; charset=utf-8"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; line-break: after-white-space;" class=""><div class=""><blockquote type="cite" class=""><div class="" style="word-wrap: break-word; -webkit-nbsp-mode: space; line-break: after-white-space;">you need to take into account the voltage divider at the input of the OTA.</div></blockquote></div><div class=""><br class=""></div>ah, okay, I thought I understood that, but was not doing anything about it! it appears to simply be, for the 13700 at least: <div class=""><br class=""></div><div class=""><div class=""><div>gm = 19.2 * Iabc * (1 / gain of input attenuator) </div><div><br class=""></div><div>Sound reasonable? Spreadsheet seems to like it ¯\_(ツ)_/¯ </div><div><br class=""></div><div><br class=""><blockquote type="cite" class=""><div class="">On Dec 11, 2020, at 12:38 PM, Tom Wiltshire <<a href="mailto:tom@electricdruid.net" class="">tom@electricdruid.net</a>> wrote:</div><br class="Apple-interchange-newline"><div class=""><meta http-equiv="Content-Type" content="text/html; charset=utf-8" class=""><div style="word-wrap: break-word; -webkit-nbsp-mode: space; line-break: after-white-space;" class="">I think Guy means that if you’re looking for the unity-gain point, you need to take into account the voltage divider at the input of the OTA. There’s a big attenuation going in, so the gain required to achieve unity gain overall will depend on the component values you choose to bring the input down to the right level. However, it *won’t* depend on the input level itself.<div class=""><br class=""></div><div class="">Is that right, Guy?</div><div class=""><br class=""></div><div class="">Tom</div><div class=""><div class=""><div class=""><br class=""></div><br class="Apple-interchange-newline">
</div>
<div class=""><br class=""><blockquote type="cite" class=""><div class="">On 11 Dec 2020, at 18:18, Chris McDowell <<a href="mailto:declareupdate@gmail.com" class="">declareupdate@gmail.com</a>> wrote:</div><br class="Apple-interchange-newline"><div class=""><span style="caret-color: rgb(0, 0, 0); font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none; float: none; display: inline !important;" class="">How would I go about this without making the cutoff frequency seem voltage dependent? If I derive gm from Vin/Iout, then the resulting frequency is dependent on the input voltage, but we know it is not. Is it just some algebra I'm overlooking to separate it out?<span class="Apple-converted-space"> </span></span></div></blockquote></div><br class=""></div></div></div></blockquote></div><br class=""></div></div></body></html>