Linear transmitter architecture using a 1-bit ΣΔ

Linearity of transmitter is a difficult point to achieve with nonconstant envelope modulation. The simplest solution is to use a class A power amplifier with sufficient back off, so that sufficient linearity can be obtained but to the detriment of the efficiency. In this paper, we present a development of the classical EER architecture where the nonconstant modulated signal is transformed into a constant one. The envelope variation is restored after an efficient power amplifier with a simple bandpass filter. The key point of this architecture is a full digital 1-bit sigma-delta modulator used to transform the envelope signal into a series of pulses working at frequencies up to 1 GHz.