Block:SC LPF - Revision history

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

2026-09-04T09:19:30Z

replace math tags with plain text (no Math extension)

← Older revision		Revision as of 09:19, 4 September 2026
Line 7:		Line 7:
	=== Design equation ===		=== Design equation ===
	Corner frequency is set by the capacitor ratio and the switch clock:		Corner frequency is set by the capacitor ratio and the switch clock:
	~~<math>~~f_c = \frac{1}{2\pi} \cdot \frac{C_2}{C_1} \cdot f_{clk}~~</math>~~		''f_c = \frac{1}{2\pi} \cdot \frac{C_2}{C_1} \cdot f_{clk}''

	=== Budgeting procedure ===		=== Budgeting procedure ===
	# Choose ~~<math>~~f_c~~</math>~~ from the signal band of interest.		# Choose ''f_c'' from the signal band of interest.
	# Pick ~~<math>~~C_1~~</math>~~ for kTC-noise floor; ~~<math>~~C_2~~</math>~~ follows from the ratio.		# Pick ''C_1'' for kTC-noise floor; ''C_2'' follows from the ratio.
	# Verify switch on-resistance gives adequate settling within the clock phase.		# Verify switch on-resistance gives adequate settling within the clock phase.
	# Run kTC noise budget ([[Method:kTC noise budget\|method]]) to confirm.		# Run kTC noise budget ([[Method:kTC noise budget\|method]]) to confirm.
Line 17:		Line 17:
	=== Known failure modes ===		=== Known failure modes ===
	* Clock feedthrough corrupting the passband.		* Clock feedthrough corrupting the passband.
	* Incomplete settling (too-high switch ~~<math>~~R_{on}~~</math>~~) causing gain error.		* Incomplete settling (too-high switch ''R_{on}'') causing gain error.
	* kTC noise dominating the front-end floor if ~~<math>~~C_1~~</math>~~ is too small.		* kTC noise dominating the front-end floor if ''C_1'' is too small.

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

Ronald: add breadcrumb navigation

2026-09-04T09:17:57Z

add breadcrumb navigation

← Older revision		Revision as of 09:17, 4 September 2026
Line 1:		Line 1:
			''← [[Blocks\|All blocks]] · durable page''

	== Switched-Capacitor Low-Pass Filter ==		== Switched-Capacitor Low-Pass Filter ==

Ronald: showcase seed

2026-09-04T09:13:16Z

showcase seed

New 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:
<math>f_c = \frac{1}{2\pi} \cdot \frac{C_2}{C_1} \cdot f_{clk}</math>

=== Budgeting procedure ===
# Choose <math>f_c</math> from the signal band of interest.
# Pick <math>C_1</math> for kTC-noise floor; <math>C_2</math> 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 <math>R_{on}</math>) causing gain error.
* kTC noise dominating the front-end floor if <math>C_1</math> is too small.

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