Analysis and design of a high power, high gain SiGe BiCMOS output stage for use in a millimeter-wave power amplifier

Abstract

Abstract-In this paper a high gain, high power output stage designed in a 250nm SiGe BiCMOS technology is presented. The used topology together with a discussion on the stability of the output stage is explained in detail. In order to increase the gain of the output stage and thus increases the attainable power added efficiency (PAE), positive feedback is used. Furthermore a formula predicting the input impedance of a common base transistor at high frequencies is deducted which explains and predicts the magnitude of the feedback mechanism. The output stage achieves a peak gain of 14.4dB at 31GHz with a maximum output power of 22dBm.

A Ka-band SiGe BICMOS power amplifier with 24 dBm output power

“…There are many configurations that can be used to make a time harmonic electromagnetic wave to rotate around the axis of propagation [1,2,5], however, the excitation of two orthogonal resonant modes by a single probe can be easier to build as well as lead a decrease in costs of manufacturing. Numerous studies on dielectric antennas with shape of cylindrical sectors were presented for linear polarization intended to reduce dimensions [6][7][8]. Tam and Murch [9] demonstrated the feasibility of a circularly polarized half-cylindrical DRA fed by a single probe.…”

“…Despite the large deviations, the mathematical analysis based on resonant cavity model with hypothetical perfect magnetic walls [15] serves as a starting point for projects of DRs that can later take advantage of numerical methods of computer simulation [11]. Figure 1 shows the geometry of a circular sector DRA, with sector angle b, radius a, and height d. The resonant frequency of the TM mpm mode inside the circular sector DRA can be written using the cavity model approximation [1,7,9,15], as f mpm 5 c 2pa…”

“…1 does not predict precisely more intricate field behavior, such as hybrid modes [1], but, to simplify the calculations, TM and HE (HEM mode that H-field is neglected in direction of propagation) are grouped as TM in this text. It was adopted the same nomenclature applied in [6][7][8][9] for cylindrical sector DRAs.…”

“…The output stage has the function of providing maximal output power combined with high‐gain and has been discussed in detail in . A differential cascode topology is used to avoid ground bounce while attaining high gain.…”

“…This is done using a differential cascode output stage biased in Class AB by means of two translinear loops which are part of the driver stage. Using a cascode output stage together with a self‐shielded balun, the voltage swing and attainable output power is maximized while the driver stage provides linearization of the output power. This leads to an output power at 1 dB compression close to the saturated output power which reduces the back‐off needed for nonconstant envelope modulated signals.…”