Hans Geltinger

A fully digital multimode polar transmitter employing 17b RF DAC in 3G mode

The constantly growing quest for global roaming with a fast mobile internet access has further increased demand for multiband 3G cell phones supporting also 2G/2.5G standards, in order to provide full coverage any time, any place. In order to substantially reduce cost and size of the multimode, multiband handsets, it is necessary to develop a transmitter architecture that enables use of a multimode, multiband power amplifier, a key prerequisite to substantially reduce the number of external components, pins count, and PCB area, while at the same time significantly lowering power consumption.

An 802.11a/b/g RF Transceiver in an SoC

The RF transceiver of a 0.13mum CMOS WLAN 802.11 a/b/g SoC for cellular applications comprising MAC, PHY, and analog front-end is presented. The transceiver with direct-conversion architecture and broadband 12GHz VCO draws 87/104mA in TX and 69/80mA in RX mode for the 2.4/5.0GHz band. The TX with control loop achieves -32dB EVM at -2dBm output power with 1.5V supply.

13.2 A digital multimode polar transmitter supporting 40MHz LTE Carrier Aggregation in 28nm CMOS

The evolving trend for increasing data rates in cellular communication systems with limited and fragmented frequency spectrum requires enhanced spectral efficiency of todays and future communication standards. The resulting need for high-order modulation schemes with large peak-to-average power ratio results in stringent requirements on in-channel linearity and SNR. At the same time FDD operation in SAW filter-less designs enforces very demanding limits for out-of-band and spurious emissions. Digital polar TX concepts have demonstrated low power consumption combined with low out-of-band noise in moderate bandwidth applications like WCDMA [1]. However, the implementation of 4G wideband polar systems with 20MHz RF bandwidth and above is very challenging due to the nonlinear conversion from cartesian to polar coordinates extending the effective signal bandwidth even further. A digital quadrature TX concept with up to 80MHz bandwidth, low EVM and moderate power efficiency has been shown in [2]. More than 30% power-added efficiency has been demonstrated in a 20MHz polar TX based on a switched-capacitor digital PA [3]. However, [2,3] suffer from low resolution and limited out-of-band noise performance.