Bottom Layer

Top Layer

SNR

CMRR

Frequency response

Stopband attenuation

other electrical characteristics

USB via FTDI232R

● supports suspend mode

 

Hardware

The changes between V1.2 and V1.3 concerns only the USB controller and an added P-MOSFET.

Since I have had more pcbs manufactured than I have used some are still left. So if you wish to obtain an empty board please feel free to contact me

Specs

As is the case for the version 1.2, I measured three monoliths of the version 1.3.

For measuring the SNR four EEG inputs were each connected via a 10k resistor to the DRL

Signal to Noise Ratio (SNR)

The CMRR was measured at 50mVpp, 10Hz over 10k resistors connected to the EEG inputs

Common mode rejection ratio (CMRR)

The CMRR was not measurable against DRL with the available equipment and was thus assumed to be below the noise threshold.

frequency response measured in Hz

Damping of aliasing frequencies measured in dB

MonolithEEG V1.3

Under contruction

In relation to the frequency response, B was not a lot better than A. On the other hand, construction unit tolerances play a stronger and unfavourable role. With the frequency response B, the Sallen key low-pass is driven more strongly into resonance. The three test monoliths can be regarded as successful, but I would not guarantee unrestricted repeatability. I would, therefore, recommend the frequency response A for the monolith.

EEG input voltage range

 

250uV

Maximum offset voltage at 100nA

 

140mV

 

 

 

Resolution

 

10 Bit / 0.5uV

Effective resolution

 

9 Bit

Noise

 

1uVpp

 

 

 

current consumption

 

60mA

Supply voltage

 

4.5 - 5.5V

Damping

#1

CH1

 

CH2

#2

CH1

 

CH2

#3

CH1

 

CH2

Mean

Simulation

-3dB HP

0.26

0.29

0.27

0.26

0.25

0.27

0.27

 

-1dB HP

0.49

0.51

0.48

0.47

0.45

0.50

0.48

 

-1dB LP

57

52

54

52

54

53

54

 

-3dB LP

64

61

62

61

62

62

62

 

Aliasing frequency

#1

CH1

 

CH2

#2

CH1

 

CH2

#3

CH1

 

CH2

Mean

Effective

Bits

128Hz

-24.4

-24.4

-24.4

-24.6

-24.4

-24.4

-24.4

 

256Hz

-49.0

-49.1

-49.0

-49.2

-50.4

-50.2

-49.5

 

300Hz

-55.5

-55.1

-55.4

-55.4

-55.5

-55.5

-55.4

 

512Hz

-80.0

-80.0

-78

-78

-78

-78

-78.7

 

#

Channel

Measured against

VGND

Measured against

DRL

1

1

2

8.9uVpp / -75dB

8.4uVpp / -75dB

<1uVpp / <-94dB

<1uVpp / <-94dB

2

1

2

9.7uVpp / -75dB

10uVpp / -74dB

<1uVpp / <-94dB

<1uVpp / <-94dB

3

1

2

9.7uVpp / -75dB

9.0uVpp / -75dB

<1uVpp / <-94dB

<1uVpp / <-94dB

#

uVpp

SNR

1

1

-54

2

1

-54

3

1

-54

Aliasing frequency

Simulation

Effective

Bits

128Hz

 

 

256Hz

 

 

300Hz

 

 

512Hz