Components

Accel-RF (ARF) has developed a number of components that are used in our system, and often provide performance that would not be available using standard off-the-shelf commercial products.  For instance, our linearized wideband VGAs offer superior performance over standard variable gain products.  We also design and manufacture several of the SSPA models employed in our systems.  In some cases, we offer these components as a stand-alone product to our customers.  For instance, we make a broadband Bias Tee, as shown below.

Bias Tees

Bias Tees are used as a choke to inject DC bias into an RF device on the input or output lines.  At RF frequencies it should appear as an open circuit so that it does not affect the RF performance.  Any such device will, by definition, have some bandwidth limitations.  For instance, using a reactive element to provide high impedance at very low frequencies yields components that are very large.  Conversely, maintaining good isolation at very high frequencies requires very small and precisely controlled elements.  The ARF bias tees were originally designed for customers using the RF-Ready DC fixtures.  They needed a convenient way to inject bias, but that allows a 50-ohm load to provide good device matching over a broad band of frequencies.  Further, since the systems support device characterization by an optional Semiconductor Parameter Analyzer (SPA), it is critical to keep the capacitive loading of the bias lines as low as possible.  Our innovative design supports all of these requirements simultaneously.

Broadband Bias Tee (1MHz to 10GHz; 1A):

Broadband Bias Tee (10MHz to 10GHz; 3A):

Two designs exists, as shown above.  The broader band design supports up to ~1A of current, whereas the narrower band supports up to over 3A.  The bandwidth tradeoff is about a decade higher low-frequency cutoff for the higher-current design.  The measured circuit performance is shown below.