Instrumentation amplifier, especially for use as a microphone pre-amplifier. It has been taped out. The specifications below are target specifications. Check back for characterized numbers once the silicon is characterized.
Requires the CACE system to run testbenches:
https://github.com/efabless/cace
Schematics for this amplifier are done in xschem and can be found in the xschem directory. Layouts for this amplifier are done in magic and can be found in the mag directory.
The CACE specification is in cace/project.txt. Testbench schematics are in the cace directory. Note that testbenches are editable in xschem, and netlists can be generated, but netlists contain variables that must be substituted by CACE and cannot simulate prior to variable substitution by CACE.
To run cace in GUI mode:
/path/to/cace_gui.py cace/project.txt
CACE can also be run from the command line as:
/path/to/cace.py cace/project.txt cace/project_out.txt -source=schematic -param=<parameter_name> -summary
Prerequisite design tools:
| Pin name | Use | Voltage Domain | Note |
|---|---|---|---|
| avdd | analog power | 3.3V | 3.3V |
| dvdd | digital power | 1.8V | 1.8V |
| avss | analog ground | ||
| dvss | digital ground | ||
| ena | enable | dvdd domain | dvdd domain |
| vinn | negative input | ||
| vinp | positive input | ||
| vout | single-ended out | ||
| gain[9:0] | programmable stage gain | dvdd domain | dvdd domain |
| ibias | bandgap-controlled bias current |
| Parameter | Min | Typical | Max | Unit | Notes |
|---|---|---|---|---|---|
| Parameter | Min | Typical | Max | Unit | Notes |
| Operating Temperature | -40 | 25 | 85 | °C | |
| Input Impedance | 10 | MΩ | High-Z for microphone sensitivity | ||
| Open loop Gain | 18 | 78 | dB | Adjustable for different use cases | |
| Frequency Response | 20 | 50000 | Hz | Audible range and machine monitoring | |
| Equivalent Input Noise | 10 | 20 | nV/√Hz | At 1kHz | |
| Total Harmonic Distortion | 0.05 | 0.1 | % | At 1kHz and nominal level | |
| Output Voltage Swing | 350 | avdd - 350 | mV | At 1 kOhms load | |
| Output Voltage Swing | 150 | avdd - 150 | mV | At 10 kOhms load | |
| Current Consumption (Enabled) | 25 | 60 | uA | Minimize for battery-powered devices | |
| Current Consumption (Disabled) | 1 | 10 | nA | ||
| CMRR (Common Mode Rejection Ratio) | 65 | 75 | dB | Important for differential inputs | |
| PSRR (Power Supply Rejection Ratio) | 65 | 75 | dB | Ensures stability with power supply fluctuations | |
| Input common-mode range | (avdd / 2) - 0.5 | avdd / 2 | (avdd / 2) + 0.5 | V | Set by internal bias circuit |
| Input range | 1 | 1000 | uV | No clipping/distortion at min and max gain | |
| Input-referred offset | -1 | 1 | mV | ||
| Output load resistance | 1 | kOhms | |||
| Slew rate | ±1 | V/us |
EF_INSTRAMP
Vendor
Efabless
130nm
Skywater
Operational Amplifier
Free
Open Source
EF Certified
Defined