RFSA2013 and RFSA2023 Broadband High Performance Voltage-Controlled Attenuators

PIN diode-based RF attenuators have been the preferred method in the past to achieve voltage-variable RF gain, but they are often troublesome to design and require a large number of associated components. A commonly used PIN diode attenuator topology based on diode quads is shown in Figure 1. Common struggles with this topology include achieving wideband frequency response due to the parasitics of the diodes, selection of appropriate resistors to match the diode attenuation versus current curve, sizable PCB land area necessary to accommodate the peripheral components, large control voltage swing, and maintaining linearity over the full attenuation range.

As seen in the June 2011 edition of Microwave Product Digest. Reprinted with permission.