Paul A. Brokaw

A complete 18-bit audio D/A converter

A voltage-output digital-to-analog converter (DAC) for digital audio applications, which combines several conventional circuit architectures, is described. It uses high-resolution laser-trimming techniques to achieve total full-scale harmonic distortion plus noise of -94 dB, without external components or adjustments. The single-chip converter is integrated with an advanced high-density bipolar/CMOS process, resulting in a 6.2-mm/sup 2/ chip area, and is assembled in a 16-pin plastic package. The logic section includes TTL/CMOS translators for the three-input serial interface, an 18-b shift register, thermometer decoder for segmentation of the four MSBs, and an edge-triggered holding register for minimizing bit skew. The analog section consists of an 18-b binary-weighted current source DAC, bipolar offset circuitry, low-noise bandgap reference, and a low-distortion amplifier to provide voltage output. The core of the chip is a combination of three different DAC structures. The four most significant bits are segmented into 15 equally weighted current cells. Segmentation was chosen to decrease the component matching needed for good differential linearity and to decrease sensitivity to component drift over time, temperature, and packaging stress.<<ETX>>

United States Patent 4,250,445

A temperature-compensated band-gap reference of the type employing two transistors operated at different current densities to develop a positive TC current. This current flows through a first resistor of nominal TC to develop a positive TC voltage which is connected in series with a negative TC voltage developed by the base-to-emitter voltage of a transistor, to produce a composite temperature compensated output voltage. The circuitry further includes a second resistor connected in series with the first resistor and having a positive TC to produce an additional compensating voltage having a temperature coefficient following a parabolic expression. This additional voltage, when connected with the other components of the output voltage, reduces the small residual inherent TC of the band-gap reference to provide a more stable reference source.

21.3 A 200nA single-inductor dual-input-triple-output (DITO) converter with two-stage charging and process-limit cold-start voltage for photovoltaic and thermoelectric energy harvesting

Energy harvesting has been considered to be a good solution to power many IoE applications [1-3]. Some applications require regulated supply voltage, while on the other hand, any extra energy should be stored in the storage element, such as a rechargeable battery, to maximize the total system efficiency. As the power delivery density is small in the energy-harvesting application, using a single inductor to transfer the power from the harvester to multiple outputs is achievable and efficient. The DITO architecture has three outputs as shown in Fig. 21.3.1: one is the regulated voltage output REG_OUT, the second is the unregulated voltage output SYS and the third is the rechargeable battery BAT. Due to the unpredictable environment conditions, the harvester could be in an environment without a corresponding energy source available for a long time. In order to keep the system operation without the harvester input VIN, the backup battery at BACK_UP is necessary, which would be the second power input of the system. The control scheme should make sure the backup battery only delivers power to the system when necessary in order not to waste any energy in the backup battery.

Still Lucky After All These Years

It seems to me that life is mostly, if not all, luck; good and bad. My good fortune has been to know, before I knew what it was to know, that I was made to do technical things.