## Second Order Intercept point(IP2) vs Third Order Intercept Point(IP3)

This page on IP2 vs IP3 describes **difference between second order intercept point(IP2) and
third order intercept point(IP3)**.
These intercept points are observed in saturated amplifier gain response.
When amplifier operates in non linear region or when it is over driven it generates intermodulation products of
input signals fed at the input.
Out of These intermodulation products second order and third order
are larger in magnitude and result into interference with the desired signals of interest.
Refer intermodulation distortion page which explains
IMD types, IMD products and mitigation techniques used to minimize effect of Passive IMD type.

### What are Intermodulation products?

As shown any amplifier device/mixing device, produce intermodulation products subjected
to two or more signals are fed to the input.
Figure shows IMD products of second and third order due to two input signals f1 and f2.

IPn= P + (ΔP/n-1),

Where, IPn is the nth order intercept point

P is the power in the fundamental frequency/tone in dBm

ΔP is the difference between the desired output and undesired nth order output product(dBc).

For Example, if two amplitude tones have a power of about +10dBm and is generating a pair of
equal amplitude 3rd order IMD products at -20dBm , calculate 2 tone IP3 of the system.

>>IP3=+10 + ((+10)-(-20)/(3-1))

IP3=25dBm

**Third Order Intercept Point (IP3):**

Figure shows both Third order Input Intercept Point and Third Order Output Intercept point with slope of 3.

OIP3 = Po + 1/2( Po - P_{IMD})

IIP3= OIP3 -Gain

IIP3= P_{IN} + 1/2( Po-P_{IMD})

**Second Order Intercept Point:(IP2)**

Figure shows both Second order Input Intercept Point(IIP2) and Second Order Output Intercept point(OIP2) with slope of 2.

IIP2= P_{IN} + Po - P_{IMD}

OIP2= Po - P_{IMD}

### Third order intercept point in cascading stages

1/OIP = (1/(G2 x G3 x OIP1)) + (1/(G3 x OIP2)) + (1/OIP3)

IIP = (OIP/(G1 x G2 x G3))

### Second order intercept point in cascading stages

1/sqrt(OIP) = (1/sqrt(G2 x G3 x OIP1)) + (1/sqrt(G3 x OIP2)) + (1/sqrt(OIP3))

IIP = (OIP/(G1 x G2 x G3))

### Calculator

Refer cascaded IP3 calculator for more.

### What is Difference between

difference between FDM and OFDM

Difference between SC-FDMA and OFDM

Difference between SISO and MIMO

Difference between TDD and FDD

Difference between 802.11 standards viz.11-a,11-b,11-g and 11-n

OFDM vs OFDMA

CDMA vs GSM