Dual RF carriers frequency translating bandpass delta sigma receiver with constant current density gm cell technique for mobile terminals

Abstract

In the past recent years, mobile communication technologies have highly developed and received much attention. In order to fulfill the advanced communication standards while ensuring backward compatibility with the conventional system, the demand for a reconfigurable and flexible radio frequency (RF) receiver is highly increased. This trend leads to the Software Define Radio (SDR) which can afford the multi-signal processing by directly sampling the RF signal. Although the Bandpass Delta Sigma Receiver (BPDSX) is a promising candidate for the SDR architecture, it has high cost problem for the advanced CMOS process and high power dissipation owing to high sampling frequency over four times RF carrier, FC. To reduce the burden of sampling frequency, frequency translating BPDSX with Non-Return to Zero (NRZ) DAC have been proposed for direct sampling at RF. However, it still have the burden of sampling frequency for high speed RF carrier and only single RF carrier is supported. In this thesis, the frequency translating BPDSX using a sinusoidal RF DAC and a constant current density (CCD) tranconductance cell technique is proposed for supporting dual RF carriers of 0.8 GHz/1.6 GHz while reducing sampling frequency indicated as Fc/N. The proposed dual RF carriers frequency translating BPDSX can provide the same performance for dual RF carrier frequency because the proposed architecture has fixed loop filter regardless of RF carriers by using a carrier frequency dependent feedback factor, $k1_C$, which is controlled by CCD tranconductance cell technique. The proposed architecture is verified by the prototype chip test. The S11 which can show the RF matching are under -12dB for the carrier frequency of 0.8 GHz (N=1) and under - 12dB for the carrier frequency of 1.6 GHz (N=2). The maximum RF voltage gains are measured as 23 dB and 19 dB for the carrier frequencies of 0.8 G Hz and 1.6 GHz, respectively. The maximum SNDR are obtained as 43 dB and 44 dB for the carrier f...