A 250 nm CMOS / LDMOS Pulse-Width Modulator and Driver for space-borne GaN switch mode power amplifiers in P-Band

Abstract

In this paper, the design of a single-chip RF PulseWidth Modulator and Driver (PWMD) aimed at exciting a 80 W class-E GaN high-power stage at 435 MHz is described. For the required buffer size, avoiding potential ringing of the pulses within the buffer structure presents a major challenge in the design process. Therefore, a smaller chip capable of driving capacitive loads of up to 5 pF was initially designed, fabricated and tested. An approach based on 3D EM simulations was used to validate the test results. Based on the presented results, an enlarged chip able to drive a 80 W GaN high-power stage is currently being designed.

Design and test of a pulse-width modulator and driver for space-borne GaN switch mode power amplifiers in P-band

“…8-PSK or π/4-DQPSK) with required values of the dynamic range in excess of 10 dB. However, using the approach of [5] by means of combining several transmit chains the dynamic range can be improved by 6 dB provided that the dynamic range of a PWMD is larger than 3.5 dB.…”

“…This degradation of the dynamic range is related to the fact that the rise and fall times of the enlarged chip are slightly larger than for the test chip. Still, the dynamic range is sufficient to enlarge the dynamic range as proposed in [5]. Other approaches [9] aiming at driving final stage devices with output power levels of at least 10 W have realized a slightly higher dynamic range (i.e.…”

“…The realizable dynamic range is 4 dB. By means of combination of four transmit paths the dynamic range is expected to improve by 6 dB to a total of 10 dB [5]. The next step is the test of the enlarged PWMD chip with a 40 W class E amplifier.…”

“…The high-power stage output matching network reconstructs the AM information by means of a resonant matching network tuned to the transmit frequency. Several of these chains can be combined at the input and output to achieve higher output power levels and larger dynamic ranges [5].…”