RF Category Block Listing

The following blocks are included in the RF category :

• Amplifier
• Antenna
• Attenuator
• Cable Loss
• Coupler
• Double Balanced Mixer
• RF Conversions
• RF Gain
• Splitter/Combiner
• Switch
• Variable Attenuator

Amplifier

This block implements a nonlinear RF amplifier. Block parameters include the amplifier small signal gain, the 1 dB compression point, second and third order intermodulation (IM) intercept points, and the amplifier noise figure. The block can also be modeled as a noiseless device. A 50 Ohm impedance is assumed.

The amplifier is modeled according to a fifth order Taylor polynomial. The polynomial coefficients are computed based on the specified gain, IP2, IP3, IP4, and the 1 dB compression point. Depending on the specified parameters values, saturation is typically achieved a few dB beyond the 1 dB compression point. Once saturation is reached, the amplifier output remains constant.

Antenna

This block models an RF antenna with gain and noise temperature specifications. Noise is added to the output based on the specified noise temperature and is not affected by the antenna gain setting. The block can also be modeled as noiseless. A 50 Ohm impedance is assumed.

The antenna gain can be specified as either fixed, or arrival-angle dependent according to a specified antenna gain pattern. In the latter case, the x2 input is used to specify the arrival angle in degrees. The block uses linear interpolation (in dB) between the specified gain pattern points.

Attenuator

This block implements a passive RF attenuator. Block parameters include the attenuator loss in decibels and the physical temperature of the device. The Attenuator block can also be modeled as noiseless. A 50 Ohm impedance is assumed.

Cable Loss

This block models a passive RF cable with a specified loss per unit distance. Noise is added to the output, when enabled, based on the specified length of the cable and its physical temperature. The block can also be modeled as noiseless. A 50 Ohm impedance is assumed.

Coupler

This block models an RF coupler. Block parameters include the coupling sense, direct path loss, coupled loss, and noise figure of the device. The Coupler block can also be modeled as noiseless. A 50 Ohm impedance is assumed.

Double Balanced Mixer

This block implements a nonlinear double balanced mixer. Block parameters include the input 1 dB compression point, third order intermodulation (IM) intercept point, conversion loss, LO power and harmonic levels, isolation, dc bias, and the mixer noise figure. The block can also be modeled as a noiseless device. A 50 Ohm impedance is assumed.

The mixer is modeled as a nonlinear amplifier (RF input) followed by a multiplier. The amplifier coefficients (3rd and 5th order) are calculated from the 1 dB compression point and IP3 setting. The amplifier output is then multiplied by the LO signal and its harmonics, which include 3rd and 5th order terms, to generate the IF output. Once the amplifier stage reaches saturation (either negative or positive), its input to the multiplier is held constant until the RF input signal drops back down below the saturating drive level.

This block can also be used to implement an unbalanced or a single balanced mixer by adjusting the RF and LO isolation settings, so as to obtain the desired level of RF or LO feedthrough at the IF output.

RF Conversions

This block implements a variety of conversions relevant to RF diagrams. The desired conversion is selected by choosing the appropriate radio button in the block’s setup dialog box.

RF Gain

This block models a perfect RF gain element (no intermodulation products). Noise is added to the output based on the specified noise figure or noise temperature of the device and its current gain setting. The block can also be modeled as noiseless. A 50 Ohm impedance is assumed.

Splitter/Combiner

This block models an RF splitter or combiner. Block parameters include the splitter mode, number of connections, additional path loss, and noise figure of the device. The block can also be modeled as a noiseless device. A 50 Ohm impedance is assumed.

Switch

This block models an RF switch. Block parameters include the switch sense, switch loss, isolation, and noise figure of the device. The block can also be modeled as a noiseless device and/or as having perfect isolation. A 50 Ohm impedance is assumed. The path selector input determines which input (or output) is active.

Variable Attenuator

This block implements a passive variable attenuator. The attenuation is controlled via external input, and can therefore be varied during the simulation. Noise is added to the output based on the specified physical temperature and the current loss value. The block can also be modeled as noiseless. A 50 Ohm impedance is assumed.