Power Supply Rejection for RF Amplifiers: Theory and Measurements

Abstract

Abstract-Supply noise is a significant problem in RF systems where it can mix with RF signals, degrading signal/noise ratios and potentially causing violation of spectral masks. This paper presents an analysis of the supply rejection properties of RF amplifiers. We extend a conventional Volterra-series formulation to treat multiport systems and use it to describe the mixing products between power supply noise and the RF carrier. It is shown that a multiport Volterra formulation can be used to treat weak nonlinearities in the system and that the nonsymmetric cross terms accurately predict low-order mixing phenomenon. We demonstrate the validity of our hand analysis through the design and fabrication of a power amplifier in 180-nm CMOS, operating between 900 MHz-2.4 GHz with a maximum output power of 15 dBm. Spectral regrowth of singletone and EDGE modulation waveforms is shown to match within 1-3 dB across frequency and input signal power. Importantly, this analysis provides insight into the circuit-level mechanisms for susceptibility to power supply noise and can help designers improve the power supply rejection ratio robustness of system-on-chip wireless blocks and transmitter architectures.Index Terms-dc-dc converter, polar modulation, power amplifier (PA), power supply rejection ratio (PSRR), RF amplifiers, supply noise.

A 5.8 GHz 1 V Linear Power Amplifier Using a Novel On-Chip Transformer Power Combiner in Standard 90 nm CMOS

“…Note that it is independent of output impedance of the other power amplifiers. Under the same conditions, the total output power, delivered to the load, equals (8) and the impedance transformation ratio is defined as (9) From (8), it can be seen that the output power can be increased either by increasing or . On the other hand, (9) shows that the impedance transformation ratio increases only linearly with but quadratically with .…”

“…In [8], a two-port Volterra analysis is formulated to quantify the distortion generated by power supply ripple in a power amplifier whose supply is provided by a DC-DC converter. Although the origin of supply ripple in our analysis is different, an analysis similar to [8] can be performed to calculate the distortion sidebands generated as a result of the power supply modulation effects.…”

“…Although the origin of supply ripple in our analysis is different, an analysis similar to [8] can be performed to calculate the distortion sidebands generated as a result of the power supply modulation effects.…”

Transformer-Coupled Converter for Voltage Modulation Techniques

“…For 50% duty cycle, two phases are connected to V¡N for every instant of time; hence, the sum of the voltages at the inputs of the set of transformers v\ + v 2 (4) At the output of the set of transformers, a constant output voltage VOUT equal to -^-is obtained.…”

“…In [3], it has been shown that the minimum bandwidth of the envelope amplifier should be 3-5 times higher than the bandwidth of the transmitted RF signal in order to obtain good levels of linearity. On the other hand, the envelope amplifier for ET does not have to reproduce exact replica of the envelope amplifier and the linearity of the RF PA depends on the employed transistor in the linear regulator as it can be seen in [4]. Different power supplies for the implementation of voltage modulation techniques have been proposed in the literature, these solutions comprise pulsewidfh modulation (PWM) topologies as in [1] and [5], multilevel converters, as in [2] or hybrid solutions that employ linear regulators [6].…”