Chapter 5: Ancillary CMOS Circuits and Measurements

The material in the previous chapter focused on a single type of RFIC circuit, the RF amplifier. Although amplifiers are extremely important for increasing signal amplitude while at the same time introducing minimal noise, a number of other on-chip functions or applications require a different set of solutions. This chapter addresses a few of these functions with examples of circuits (and accompanying analysis) used to improve device performance. Q-enhancement, stage buffering, and gain control circuits are covered in this chapter. Filters are briefly covered to show how they may be integrated into gain blocks for conservation of silicon real estate. A section on the basics of power harvesting (dc power generation from an externally applied RF signal) is also covered. This circuit type is finding increasing use in self-powered RFICs such as are found in radio frequency identification (RFID) applications.

The design principles described in this and previous chapters are just one part of the overall RFIC development process. Closing the design-fabrication-test loop often requires that measurements be performed on circuit prototypes to ensure that the design and simulation phase has considered important parasitic and other circuit nonidealities. The focus of the final section in this chapter is the influence of on-chip measurement structures on the design RFIC circuit element. Techniques are also covered on how to remove or deembed the desired RFIC circuit measurement parameters from those of the overall measurement data.