Retina Chip Wiki - User contributions [en]

Method:kTC noise budget

2026-09-04T09:19:31Z

Ronald: replace math tags with plain text (no Math extension)

''← [[Methods|All methods]]''

== kTC noise budget ==
Switched-cap kTC noise budgeting procedure.

''v_{n,kTC} = \sqrt{\frac{kT}{C}}''

''TBD — flesh out.''

Block:SC LPF RC1.9

2026-09-04T09:19:31Z

Ronald: replace math tags with plain text (no Math extension)

''← back to [[Block:SC LPF|SC LPF (durable)]] · [[RC1.9|chip: RC1.9]] · [[Blocks|all blocks]]''

== SC LPF — RC1.9 instance ==
Real component values and measured results for the RC1.9 silicon (TSMC 28nm HPC+).

{| class="wikitable"
|-
! Parameter !! Value
|-
| ''C_1'' || TBD
|-
| ''C_2'' || TBD
|-
| ''f_{clk}'' || TBD
|-
| ''f_c'' (target) || TBD
|-
| Supply || 0.9 V
|}

=== Post-PEX / measured ===
''TBD'' — fill from the weekly slides / bench measurements.

=== Errata ===
''TBD''

''(This page demonstrates the durable/instance split.)''

Block:SC LPF

2026-09-04T09:19:30Z

Ronald: replace math tags with plain text (no Math extension)

''← [[Blocks|All blocks]] · durable page''

== Switched-Capacitor Low-Pass Filter ==

A switched-capacitor low-pass filter follows the Gm-C integrator in the AFE to band-limit the neural/recording signal before digitisation by the [[Block:SAR ADC|SAR ADC]].

=== Design equation ===
Corner frequency is set by the capacitor ratio and the switch clock:
''f_c = \frac{1}{2\pi} \cdot \frac{C_2}{C_1} \cdot f_{clk}''

=== Budgeting procedure ===
# Choose ''f_c'' from the signal band of interest.
# Pick ''C_1'' for kTC-noise floor; ''C_2'' follows from the ratio.
# Verify switch on-resistance gives adequate settling within the clock phase.
# Run kTC noise budget ([[Method:kTC noise budget|method]]) to confirm.

=== Known failure modes ===
* Clock feedthrough corrupting the passband.
* Incomplete settling (too-high switch ''R_{on}'') causing gain error.
* kTC noise dominating the front-end floor if ''C_1'' is too small.

=== Instances ===
* [[Block:SC LPF RC1.9|RC1.9]] — implemented, post-PEX verified
* [[Block:SC LPF RC2.0|RC2.0]] — ''TBD''

MediaWiki:Common.css

2026-09-04T09:19:08Z

Ronald: add chat widget

/* Retina Chip Wiki chat widget styles (wiki3.rohmega.com) */

#rmg-chat-toggle {
position: fixed;
bottom: 20px;
right: 20px;
width: 56px;
height: 56px;
border-radius: 50%;
border: none;
background: #3366cc;
color: #fff;
font-size: 26px;
cursor: pointer;
box-shadow: 0 2px 12px rgba(0, 0, 0, 0.3);
z-index: 10000;
line-height: 1;
}
#rmg-chat-toggle:hover {
background: #2a55aa;
}

#rmg-chat-panel {
position: fixed;
bottom: 88px;
right: 20px;
width: 340px;
max-width: 90vw;
height: 460px;
max-height: 70vh;
background: #fff;
border: 1px solid #ccc;
border-radius: 12px;
box-shadow: 0 4px 24px rgba(0, 0, 0, 0.25);
display: flex;
flex-direction: column;
z-index: 10000;
overflow: hidden;
}

#rmg-chat-head {
background: #3366cc;
color: #fff;
padding: 10px 14px;
font-weight: bold;
display: flex;
justify-content: space-between;
align-items: center;
font-size: 14px;
}
#rmg-chat-head button {
background: none;
border: none;
color: #fff;
font-size: 22px;
cursor: pointer;
line-height: 1;
}

#rmg-chat-msgs {
flex: 1;
overflow-y: auto;
padding: 12px;
display: flex;
flex-direction: column;
gap: 8px;
}

.rmg-bubble {
max-width: 85%;
padding: 8px 12px;
border-radius: 14px;
font-size: 14px;
line-height: 1.4;
white-space: pre-wrap;
word-wrap: break-word;
}
.rmg-bubble.user {
align-self: flex-end;
background: #3366cc;
color: #fff;
border-bottom-right-radius: 4px;
}
.rmg-bubble.bot {
align-self: flex-start;
background: #f0f0f0;
color: #222;
border-bottom-left-radius: 4px;
}

#rmg-chat-foot {
display: flex;
border-top: 1px solid #ddd;
padding: 8px;
gap: 6px;
}
#rmg-chat-input {
flex: 1;
border: 1px solid #ccc;
border-radius: 18px;
padding: 8px 14px;
font-size: 14px;
}
#rmg-chat-send {
border: none;
background: #3366cc;
color: #fff;
border-radius: 18px;
padding: 8px 16px;
cursor: pointer;
font-size: 14px;
}
#rmg-chat-send:disabled {
opacity: 0.5;
cursor: default;
}

MediaWiki:Common.js

2026-09-04T09:19:08Z

Ronald: add chat widget

/**
* Retina Chip Wiki chat widget (wiki3.rohmega.com).
* Floating chat bubble in the bottom-right. Grounded Q&A over the wiki.
* Public wiki -> the backend enforces a daily token budget.
*
* ES5-safe only: ResourceLoader minifier rejects trailing commas in call args,
* arrow functions, template literals.
*/
(function () {
'use strict';

// Don't double-inject
if (document.getElementById('rmg-chat-root')) {
return;
}

var CHAT_ENDPOINT = '/chat/chat'; // same-origin via Caddy /chat/* -> :8111

function buildUI() {
var root = document.createElement('div');
root.id = 'rmg-chat-root';

// --- floating toggle button ---
var btn = document.createElement('button');
btn.id = 'rmg-chat-toggle';
btn.setAttribute('aria-label', 'Ask the wiki');
btn.textContent = '💬';
root.appendChild(btn);

// --- panel ---
var panel = document.createElement('div');
panel.id = 'rmg-chat-panel';
panel.style.display = 'none';

var head = document.createElement('div');
head.id = 'rmg-chat-head';
var title = document.createElement('span');
title.textContent = 'Ask the Retina Chip Wiki';
var close = document.createElement('button');
close.textContent = '×';
close.setAttribute('aria-label', 'Close');
head.appendChild(title);
head.appendChild(close);
panel.appendChild(head);

var msgs = document.createElement('div');
msgs.id = 'rmg-chat-msgs';
panel.appendChild(msgs);

var foot = document.createElement('div');
foot.id = 'rmg-chat-foot';
var input = document.createElement('input');
input.id = 'rmg-chat-input';
input.setAttribute('placeholder', 'Ask about blocks, ADRs, methods…');
var send = document.createElement('button');
send.id = 'rmg-chat-send';
send.textContent = 'Send';
foot.appendChild(input);
foot.appendChild(send);
panel.appendChild(foot);

root.appendChild(panel);
document.body.appendChild(root);

// wire events
btn.addEventListener('click', function () {
var open = panel.style.display !== 'none';
panel.style.display = open ? 'none' : 'block';
});
close.addEventListener('click', function () {
panel.style.display = 'none';
});
send.addEventListener('click', ask);
input.addEventListener('keydown', function (e) {
if (e.key === 'Enter') {
ask();
}
});
}

function addBubble(text, who) {
var msgs = document.getElementById('rmg-chat-msgs');
var b = document.createElement('div');
b.className = 'rmg-bubble ' + who;
b.textContent = text;
msgs.appendChild(b);
msgs.scrollTop = msgs.scrollHeight;
return b;
}

function ask() {
var input = document.getElementById('rmg-chat-input');
var send = document.getElementById('rmg-chat-send');
var q = input.value.trim();
if (!q) {
return;
}
input.value = '';
addBubble(q, 'user');
send.disabled = true;

var typing = addBubble('…', 'bot');

var xhr = new XMLHttpRequest();
xhr.open('POST', CHAT_ENDPOINT, true);
xhr.setRequestHeader('Content-Type', 'application/json');
xhr.onreadystatechange = function () {
if (xhr.readyState !== 4) {
return;
}
send.disabled = false;
if (xhr.status === 200) {
try {
var d = JSON.parse(xhr.responseText);
typing.textContent = d.answer || '(no answer)';
} catch (err) {
typing.textContent = 'Error reading response.';
}
} else {
try {
var e = JSON.parse(xhr.responseText);
typing.textContent = e.answer || ('Error ' + xhr.status);
} catch (err) {
typing.textContent = 'Error ' + xhr.status;
}
}
};
xhr.send(JSON.stringify({ message: q }));
}

// Run after DOM ready
if (document.readyState === 'loading') {
document.addEventListener('DOMContentLoaded', buildUI);
} else {
buildUI();
}
})();

Method:Calibre setup

2026-09-04T09:17:58Z