This work discusses the efficiency bandwidth constrains in Doherty amplifiers. An analysis of the bandwidth limitations imposed by the impedance inverter and output capacitance of the active devices is given. Alternative wideband matching and output connection schemes for Doherty amplifiers are evaluated for their efficiency performance both at full output power, as well as, in power back-off operation. The presented theory is verified using a Doherty demonstrator amplifier, which allows independent control of the input signals for the main and peak device. The related measurements show the largest high-efficiency bandwidth reported up to date for a Doherty amplifier.
A CMOS D-band 135-150 GHz transmitter is presented with integrated digital control and on-chip antenna. The proposed transmitter employs an IF feed-forward compensation scheme which improves the soft gain compression of the power amplifier by 5.1dB to provide an overall more linear AM-AM profile allowing reduced power back-off for modulation schemes with a high peak-to-average ratio. The proposed D-band transmitter consumes 255mW and occupies 2000 x 1500 um of silicon area. The proposed transmitter delivers a 0.4 dBm EIRP and a saturated power on chip of 13.2 dBm. The transmitter has a peak PAE of 8.2% with power delivered to the antenna and a peak PAE of 0.4% when considering radiated power.
In modern CMOS technologies, metal dummy fills are required to maintain metal density uniformity and to planarize the layers. As frequency increases, the effect of the metal dummy fills on the CMOS integrated circuits or components should be taken into account. This work presents experimental results of the effect of metal dummy fills on the microwave behavior of spiral inductors fabricated in a standard 0.
18-µm CMOS technology. The influences on the equivalent model parameters and the Q-factor are characterized based on measured S-parameters of inductors with and without metal dummy fills.Index Terms -CMOS technology, chemical-mechanical polishing process (CMP), metal dummy fills, microwave measurements, spiral inductors.
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