Hi,

I wonder how to calculate the Signal-to-Noise Ratio with the datasheet
of a CMOS sensor?

I calculate the total excited photons (Signal_N) from the irradiance,
conversion gain and quantum efficiency.

But, I am confused with the noise estimation.

The datasheet gives,

Parameter                     Specification        Remarks
FPN                              <3% RMS           <10% p/p
PRNU                            2% RMS             Half saturation
Conversion gain              16uV/electron
Output amplitude             1V                      Unity gain.
Saturation charge             62.500e-
Temporal noise                 45e-
S/N ratio                          1330=60000:45=62dB
Parasitic light sensitivity    <0.5%

Here, I just estimate the noise like bellow,
Shot noise, sqrt(Signal_N)
Temporal noise, 45

Thus, Noise_N = sqrt(Signal_N + 45^2),
and the SNR is given by,

SNR = 20log10(Signal_N / Noise_N)

Is it correct?

And furthermore, what confused me most is the meaning of FPN in the
datasheet, and what does "<3%RMS" mean here?

Shoud I consider the FPN in the noise estimation? And, how?

Any help would be appreciated!

Best regards,

Chen

On May 7, 7:52 am, kyori <ggky... at (no spam) gmail.com> wrote:





Hi,

I wonder how to calculate the Signal-to-Noise Ratio with the datasheet
of a CMOS sensor?

I calculate the total excited photons (Signal_N) from the irradiance,
conversion gain and quantum efficiency.

But, I am confused with the noise estimation.

The datasheet gives,

Parameter Specification Remarks
FPN <3% RMS <10% p/p
PRNU 2% RMS Half saturation
Conversion gain 16uV/electron
Output amplitude 1V Unity gain.
Saturation charge 62.500e-
Temporal noise 45e-
S/N ratio 1330=60000:45=62dB
Parasitic light sensitivity <0.5%

Here, I just estimate the noise like bellow,
Shot noise, sqrt(Signal_N)
Temporal noise, 45

Thus, Noise_N = sqrt(Signal_N + 45^2),
and the SNR is given by,

SNR = 20log10(Signal_N / Noise_N)

Is it correct?

And furthermore, what confused me most is the meaning of FPN in the
datasheet, and what does "<3%RMS" mean here?

Shoud I consider the FPN in the noise estimation? And, how?

Any help would be appreciated!

Best regards,

Chen

I suggest you obtain the CMOS detector and measure it yourself.
Trying to get accurate values from a data sheet is not too reliable.
The true value is dependent on your application.- Òþ²Ø±»ÒýÓÃÎÄ×Ö -

- ÏÔʾÒýÓõÄÎÄ×Ö -

Helpful person wrote:
On May 7, 7:52 am, kyori <ggky... at (no spam) gmail.com> wrote:
Hi,

I wonder how to calculate the Signal-to-Noise Ratio with the datasheet
of a CMOS sensor?

I calculate the total excited photons (Signal_N) from the irradiance,
conversion gain and quantum efficiency.

But, I am confused with the noise estimation.

The datasheet gives,

Parameter Specification Remarks
FPN <3% RMS <10% p/p
PRNU 2% RMS Half saturation
Conversion gain 16uV/electron
Output amplitude 1V Unity gain.
Saturation charge 62.500e-
Temporal noise 45e-
S/N ratio 1330=60000:45=62dB
Parasitic light sensitivity <0.5%

Here, I just estimate the noise like bellow,
Shot noise, sqrt(Signal_N)
Temporal noise, 45

Thus, Noise_N = sqrt(Signal_N + 45^2),
and the SNR is given by,

SNR = 20log10(Signal_N / Noise_N)

Is it correct?

And furthermore, what confused me most is the meaning of FPN in the
datasheet, and what does "<3%RMS" mean here?

Shoud I consider the FPN in the noise estimation? And, how?

Any help would be appreciated!

Best regards,

Chen

I suggest you obtain the CMOS detector and measure it yourself.
Trying to get accurate values from a data sheet is not too reliable.
The true value is dependent on your application.

FPN is 'fixed-pattern noise'. CMOS sensors have an amplifier per pixel,
whereas CCDs have an amplifier per output. Each amplifier has its own
gain and offset variation, so a uniformly-illuminated sensor produces a
nonuniform output. (With narrowband illumination, especially laser
light, there are nasty etalon fringes that form in the microlenses on
top of the sensor chip as well.)

For applications where this is a problem, you need to apply gain and
offset corrections pixel-by-pixel. This isn't especially difficult on
the software side--it's mainly getting the test illumination really
uniform that causes the worries.

Image sensor data sheets are famous for being useless--if you're
designing cell phone cameras, the manufacturer will talk to you, but
it's harder otherwise.

Cheers,

Phil Hobbs- Òþ²Ø±»ÒýÓÃÎÄ×Ö -

- ÏÔʾÒýÓõÄÎÄ×Ö -

Helpful person wrote:
On May 7, 7:52 am, kyori <ggky... at (no spam) gmail.com> wrote:
Hi,

I wonder how to calculate the Signal-to-Noise Ratio with the datasheet
of a CMOS sensor?

I calculate the total excited photons (Signal_N) from the irradiance,
conversion gain and quantum efficiency.

But, I am confused with the noise estimation.

The datasheet gives,

Parameter Specification Remarks
FPN <3% RMS <10% p/p
PRNU 2% RMS Half saturation
Conversion gain 16uV/electron
Output amplitude 1V Unity gain.
Saturation charge 62.500e-
Temporal noise 45e-
S/N ratio 1330=60000:45=62dB
Parasitic light sensitivity <0.5%

Here, I just estimate the noise like bellow,
Shot noise, sqrt(Signal_N)
Temporal noise, 45

Thus, Noise_N = sqrt(Signal_N + 45^2),
and the SNR is given by,

SNR = 20log10(Signal_N / Noise_N)

Is it correct?

And furthermore, what confused me most is the meaning of FPN in the
datasheet, and what does "<3%RMS" mean here?

Shoud I consider the FPN in the noise estimation? And, how?

Any help would be appreciated!

Best regards,

Chen

I suggest you obtain the CMOS detector and measure it yourself.
Trying to get accurate values from a data sheet is not too reliable.
The true value is dependent on your application.

FPN is 'fixed-pattern noise'. CMOS sensors have an amplifier per pixel,
whereas CCDs have an amplifier per output. Each amplifier has its own
gain and offset variation, so a uniformly-illuminated sensor produces a
nonuniform output. (With narrowband illumination, especially laser
light, there are nasty etalon fringes that form in the microlenses on
top of the sensor chip as well.)

For applications where this is a problem, you need to apply gain and
offset corrections pixel-by-pixel. This isn't especially difficult on
the software side--it's mainly getting the test illumination really
uniform that causes the worries.

Image sensor data sheets are famous for being useless--if you're
designing cell phone cameras, the manufacturer will talk to you, but
it's harder otherwise.

Cheers,

Phil Hobbs- Òþ²Ø±»ÒýÓÃÎÄ×Ö -

- ÏÔʾÒýÓõÄÎÄ×Ö -

FPN is 'fixed-pattern noise'.  CMOS sensors have an amplifier per pixel,
whereas CCDs have an amplifier per output.  Each amplifier has its own
gain and offset variation, so a uniformly-illuminated sensor produces a
nonuniform output.  (With narrowband illumination, especially laser
light, there are nasty etalon fringes that form in the microlenses on
top of the sensor chip as well.)

For applications where this is  a problem, you need to apply gain and
offset corrections pixel-by-pixel.  This isn't especially difficult on
the software side--it's mainly getting the test illumination really
uniform that causes the worries.

Image sensor data sheets are famous for being useless--if you're
designing cell phone cameras, the manufacturer will talk to you, but
it's harder otherwise.

Cheers,

Phil Hobbs- Hide quoted text -

- Show quoted text -

I wonder how our friends at Schott would feel about having their name
applied to shot noise. ;-)

Return address scrambled. Replace nkbob with bobkn.

Top posting - a way of life.

"Helpful person" <rrl... at (no spam) yahoo.com> wrote in message

news:447c889b-57e3-46a5-a2ff-fdf35c942007 at (no spam) c65g2000hsa.googlegroups.com...

(snip)

In addition schott (quantum) noise can become significant.

(snip)

On May 7, 7:52 am, kyori <ggky... at (no spam) gmail.com> wrote:
Hi,

I wonder how to calculate the Signal-to-Noise Ratio with the datasheet
of a CMOS sensor?

I calculate the total excited photons (Signal_N) from the irradiance,
conversion gain and quantum efficiency.

But, I am confused with the noise estimation.

The datasheet gives,

Parameter Specification Remarks
FPN <3% RMS <10% p/p
PRNU 2% RMS Half saturation
Conversion gain 16uV/electron
Output amplitude 1V Unity gain.
Saturation charge 62.500e-
Temporal noise 45e-
S/N ratio 1330=60000:45=62dB
Parasitic light sensitivity <0.5%

Here, I just estimate the noise like bellow,
Shot noise, sqrt(Signal_N)
Temporal noise, 45

Thus, Noise_N = sqrt(Signal_N + 45^2),
and the SNR is given by,

SNR = 20log10(Signal_N / Noise_N)

Is it correct?

And furthermore, what confused me most is the meaning of FPN in the
datasheet, and what does "<3%RMS" mean here?

Shoud I consider the FPN in the noise estimation? And, how?

Any help would be appreciated!

Best regards,

Chen

I suggest you obtain the CMOS detector and measure it yourself.
Trying to get accurate values from a data sheet is not too reliable.
The true value is dependent on your application.

Do you have any idea the average FPN would be how many e-?

The sensor here is Cypress LUPA-1300,

It is a high speed CMOS sensor, and I may use it in low illuminace
conditions.

I donnt know if I get any signal while the photons excited is below
certain value.

Best regards,

Chen