A single-ended direct conversion front-end transmitter with ESD protection for WiMAX application

This paper realized a single-ended direct conversion front-end transmitter for Worldwide Interoperability for Microwave Access (WiMAX) application. The on chip output matching network is designed in the power amplifier driver to provide the convenience of measurement and further integration with a power amplifier, which is usually designed as a single input. Moreover, the gain adjustment with 1 dB step is implemented in RF programmable gain amplifier (PGA) which controls 29 dB gain dynamic range and 0.4 dB maximum relative gain error with 1 dB resolution. Digital-to-analog converters (DACs) are also designed for carrier leakage, DC offset, and unbalanced I/Q LO signals, resulted from process variation. Due to symmetric layout and matching components, and calibration techniques on the divide-by-2 circuit and the I/Q modulator, sideband and carrier suppression can achieve 48.52 dBc and 49.83 dBc, respectively. The EVM of -37.53 dB can be achieved with -15 dBm output power. The front-end transmitter dissipates 108.2 mA from 3.3 V power supply, which occupies 2972 um × 1300 um of chip area including ESD protected pads and three wire control circuit.