A power-efficient injection-locked class-E power amplifier for wireless sensor network

Abstract

In this letter, we present an injection-locked Class-E power amplifier (Class-E ILPA) suitable for 2.4-GHz wireless sensor network applications where the maximum transmit-power is typically about 10 dBm. In such a low transmit-power application, it is a great challenge to achieve a high transmit efficiency because the driving power and dc power consumption in the previous stage are no more negligible compared with the transmitted signal power. The proposed Class-E ILPA, which is fully integrated in 0.18-m CMOS technology, achieves the power added efficiency of 44.5% while delivering the output power of 11 dBm with drain efficiency of 49.3% at 1.2-V supply voltage. The measured locking range reaches 300 MHz with the input driving power of 6 dBm.Index Terms-Class-E power amplifier (PA), injection-locked (IL), power oscillator, wireless sensor network (WSN).

A 2.5-GHz 1-V High Efficiency CMOS Power Amplifier IC with a Dual-Switching Transistor and Third Harmonic Tuning Technique

“…Unfortunately, efficiency and supply voltage represent a trade-off in switching-mode power amplifiers (PAs). Several techniques have been proposed for improving efficiency at low supply voltages [6][7][8][9][10][11]. The fully integrated PAs with a power combiner, such as multiple LC baluns [6], a transformer [7], and a distributed active transformer [8,9], were proposed to boost the power added efficiency (PAE) at low supply voltages.…”

“…However, large combiners lead to high insertion losses and enlarge the chip size. Another approach to increase the efficiency of a low supply voltage PA is an injection-locking technique [10,11]. Although this technique provides high gain and high efficiency, the circuit is complicated.…”

‘New’ solutions of Class‐E power amplifier with finite dc feed inductor at any duty ratio

“…The switch-mode power amplifier, especially Class-E PA, whose ideal efficiency reaches 100%, can be a good way to solve the problem above. Sokal and Sokal [1] proposed a structure of Class-E PA and then Rabb [2] analysed the performance of Class-E PA. Based on the current research direction of Class-E PA, it can be divided into two categories: Class-E PA with RF choke [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18] and Class-E PA with finite dc feed (FDC) inductor [19][20][21][22][23][24][25]. From the point of view on the switch voltage, Class-E PA has three operating modes: non-zero-voltage switching (non-ZVS), suboptimal operation [ZVS and non-zero-voltage derivative switching (non-ZDS)] and optimal operation (ZVS and ZDS) [1,2].…”

A design methodology of transformer-based class-E power amplifier

“…The concept of the injection-locking technique was adopted in a PA by Oh [47], and the injection-locking class-E PA achieves high PAE with low driving power. The approach is to use the small-signal equivalent circuit to predict the boundary condition of the oscillation, and the derivation of the oscillation condition can be obtained.…”