A Quadrature Switched Capacitor Power Amplifier

Analysis of Switched Capacitor Losses in Polar and Quadrature Switched Capacitor PAs

“…III. Q50 SCPAS The Q50 Cartesian SCPA was introduced in [3] and was indicated in Figure 1b. In this section, its output power P out,Q50 and SC loss P SC,Q50 are derived.…”

“…In this section, its output power P out,Q50 and SC loss P SC,Q50 are derived. Whereas [3] assumes equal I and Q signals, this section analyzes the more realistic case with arbitrary phase and amplitude modulation. Fig.…”

“…To improve SCPA efficiency, multiple techniques have been proposed, such as class G [3], [5], Doherty [6], sub-harmonic switching (SHS) [7] or combinations [8], [9]. The common characteristic of these techniques is that they all achieve back-off without driving the capacitive divider at a back-off code, maintaining the efficiency of α = 1.…”

“…A 20MHz complex sine wave is used as baseband input signal. C is chosen 5 pF, in the order magnitude of the values in [2] and [3]. An overview of all design variables is given in Table I.…”

“…(e-mail: j.o.p.zanen@utwente.nl) connecting the outputs of two sub-SCPAs with C/2 capacitance each and 90 • phase shifted LOs. This yields a capacitive divider, combining the quadrature signals [3].…”