A 100 MHz Hybrid Supply Modulator With Ripple-Current-Based PWM Control

This paper presents a 100 MHz hybrid supply modulator (HSM) with ripple-current-based pulse width modulation (PWM) control. By sensing the ripple current, a ripple current sensor (RCS) is able to overcome the bandwidth limitation of an absolute current sensor. By leveraging the RCS, we propose a large-signal PWM control method for HSMs. This method has an intrinsically fast switching loop, and thus eliminates the need for the feed-forward path used in many previous designs. The possibility of generating high-order harmonics in PWM-controlled HSMs is pointed out for the first time, and design recommendations to avoid them are presented. A very-high-frequency triangular wave generator that is robust to both process-voltage-temperature (PVT) variations and device mismatches is proposed. A proof-of-concept prototype was fabricated in CMOS 130 nm technology. Switching at 100 MHz, this HSM is able to track a 0.8 V
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sinusoidal waveform up to 13 MHz with high fidelity. It achieves a peak efficiency of 88.2% at the maximum output power of 23 dBm. To the best of our knowledge, this is the first PWM-controlled HSM that is able to operate at 100 MHz.