Third order distortion products are typically introduced in an RF system by components such as mixers and amplifiers. Spectrum analyzer can be used to measure the TOI distortion. In this section, we will show the TOI distortion measurement by using Saluki S3532 spectrum analyzer.

Fig.1 S3532 spectrum analyzer

In the following example, use two signal generator to generate a 500MHz, -10dBm Sine signal and a 501MHz, -10dBm sine signal.

1. Connect the outputs of two signal generators to the spectrum analyzer RF input port using a T-shaped connector, as shown in Fig.2 below.

Fig.2 TOI distortion measurement connection

2. Press [Preset] key to return the instrument to default status.

3. Set test frequency.

(1) Press [FREQ] key

(2) Select [Ctr FREQ] and input 500MHz

(3) Press [SPAN] key

(4) Select [SPAN] and input 5MHz

(5) Press [BW] key

(6) Select [Res BW Auto Man] and input 1kHz

4. Use [Peak] and [Marker] keys to do the analyze.

(1) Press [Peak]key, S3532 will search the MAX value and mark it with a marker 1.

(2) Press [Marker] key.

(3) Select [Delta], a Marker 2 is activated and it is a Delta marker, the reference marker is Marker 1.

(4) Press [Peak] key. Select [Next Peak].

5.  Readout the value of Marker 2. It is the TOI distortion in Fig.3.

Fig.3 TOI distortion measurement