CNR_OTA_SKY130NM

Who

Carsten Wulff

Why

In most books I find that CMFBs and fully differential OTAs are missing. When I make switched-cap examples, like TB_CNROTA_SCAMP, I need a fully differential OTA.

How

My go-to fully differential current mirror OTA with a level-shifter based CMFB and a OTA to control the common mode.

Download/Clone

See install.md

What

What	Lib/Folder	Cell/Name
Schematic	CNR_OTA_SKY130NM	CNR_OTA
Example usage Schematic	TB_CNR_OTA	TB_CNROTA_SCAMP
Back annotation TB	TB_CNR_OTA	TB_CNROTA_OP

Details in documents/schematic.md

Changelog/Plan

Version	Status	Comment
0.1.0	✅	First version

Signal interface

Signal	Direction	Domain	Description
VDD_1V8	Input	VDD_1V8	Main supply
VIN	Input	VDD_1V8	Negative input
VIP	Input	VDD_1V8	Positive input
VOP	Input	VDD_1V8	Positive output
VON	Input	VDD_1V8	Negative output
LPCO	Output	VDD_1V8	Common mode loop output
LPCI	Input	VDD_1V8	Common mode loop input. Short to LCPO
IBPSR	Input	VDD_1V8	Bias current (2 uA )
VSS	Input	Ground

Dependencies

Library	Description
CNR_ATR_SKY130NM	Quantized analog transistors
SUN_TR_SKY130NM	Standard digital cells and Resistors
RPLY_BIAS_SKY130NM	PTAT current source, used in TB_CNROTA_SCAMP
tech_sky130B	Technology setup
cpdk	Borders. Loop stability setup

Key parameters

Parameter	Min	Typ	Max	Unit
Technology		Skywater 130 nm
AVDD	1.7	1.8	1.9	V
Temperature	-40	27	125	C
Loop gain (fb=500k,in=100k)	63	68	72	dB
Bias current		2		uA
Current from VDD		92		uA
Load capacitance	5			pF

See sim/CNR_OTA/README.md for detailed results

Status

Stage	TYPE	Status	Comment
Specification	DOC	✅
Schematic	VIEW	✅
Schematic simulation	VER	✅
Layout	VIEW	❌
Layout parasitic extraction	VIEW	❌
LPE simulation	VER	❌
LVS	VER	❌
DRC	VER	❌
ERC	VER	❌
ANT	VER	❌