stepped attenuator in RF chain justification

Question

hello 
 
 I am designing the RF part of the transmitter chain shown in the figure below. The signal level measured from the modulator's output ranges of -30 dBm. This design aims to amplify this signal and deliver variable power in the range of 37-40 dBm to the antenna. To achieve this goal, HMC3587LP3BE amplifiers have been used as gain blocks; the driver amp is HMC441LC3B and also qorvuqpa1011 is used as the power amplifier. In this chain, an HMC424ALH5 stepped attenuator has been used to change the power level. Since this stepped attenuator has an acceptable attenuation resolution, Is the use of this attenuator in this scheme justifiable?

enash · Accepted Answer

Your drawing indicates that the input frequency is 8 GHz. HMC424 is specified to operate form dc to 3 GHz. So you are going to need a higher frequency attenuator. I'm not sure of your question "is the use of this attenuator in this schematic" justifiable. From a signal balancing perspective, I would probably move the attenuator more to the center of the signal chain. There are models for all of these components in ADIsimRF (you can make a custom model for the Qorvo part). The software allows you to do frequency and DSA attenuation sweeps ( www.analog.com/adisimrf ))

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stepped attenuator in RF chain justification