Digitally Place and Routed Up-converting Bandpass DAC

By manipulating digital tools to include a single analog cell, the complete DAC and IF transmit path of a radio is automatically placed and routed in 0.12 mm². Implemented in 0.18 mum CMOS, an over-sampled SigmaDelta modulator quantizes the data stream and a semi-analog filter selects a replica of the desired signal at IF. Based on instances of a 5-transistor analog cell, an integrated mixed-signal filter picks off the desired replica, filters the quantization noise, and delivers an analog IF output. Transmitting at an IF of 192 MHz, measurements confirm that the DAC, mixer and filter have a bandwidth of 3.2 MHz, 12-bit linearity and consume 32 mW. Despite automated layout, the circuit consumes less than 1/10th the area and 1/6th the power of custom up-converting designs. The area, power, bandwidth and output frequency are a function of the digital modulator, and scale with technology