A state-space behavioral model for CMOS class E power amplifiers

Abstract

Class E amplifiers are imposed by time-domain constraints. This makes the design of such amplifiers more difficult than other types of amplifiers. This paper presents a new method to analyze Class E power amplifiers using state-space equations. A description by these equations makes it possible to find the correct initial conditions that leads to the steady-state solution of the amplifier. Furthermore, it is possible to derive the power balance of the power amplifier based on its state-space equations. The presented method has shown to be very valuable when designing switched power amplifiers. Furthermore, the method can also be applied for power amplifiers that do not fulfill the Class E switching conditions.

Design of a linearly assisted switcher for a supply modulated RF transmitter

“…A state model (see e.g., [5]) is built for both states (switch positions) of the circuit shown in Fig. 3.…”

Behavioral modeling of Class-E switching circuits via Weierstrass canonical form

“…Therefore, an effective model that simulates the steady state behavior of Class-E amplifier is required. The behavioral models [12,13] fulfill this purpose. The behavioral models are obtained via the simplified circuits that are given by replacing MOSFET including in a Class-E amplifier with an ideal switch.…”

“…The behavioral models are obtained via the simplified circuits that are given by replacing MOSFET including in a Class-E amplifier with an ideal switch. Then, the dynamics of the simplified circuits can be analyzed by using knowledge of control community [12,13]. Moreover, in [13], the simplified circuit is formulated by modified nodal analysis (MNA) [14] that makes the formulation easy for any modification of circuit configuration.…”

Optimization procedure of class E amplifiers using SPICE

“…1, where the circuit consists of input voltage Î , dc-feed inductor Ä , MOS switch Ë, shut capacitor Ë to the switch, a series resonant circuit composed of inductor Ä ¼ and capacitor ¼ , and output resistor R. In order to attain the high-efficiency, all the losses occur during switching should be minimized, which demands that the drain-source voltage when the switch closes is zero. Furthermore, it is necessary that the time derivative of the switch voltage is also equal to zero at the switching moment [1]. As a result, the requirements as Figure 3: CR amplifier, where…”

“…A Class E amplifier is the best choice as the power amplifier which is capable of combining a high efficiency ( ¼±) with a resonant output power (30 dBm) [1]. It is a good candidate for CMOS transceiver, because the switching type amplifiers do not obstruct the constant envelope modulation like Global System for Mobile Communication and Bluetooth.…”