Semiconductor History

Back in the day I knew about DSD (Direct Stream Digital) and SACD (Super Audio CD) but it passed me by. I was still in Burr-Brown when DSD data converter ICs were first being developed by the design team in Japan, and I'm sure I was present when they were being presented at seminars to customers, but at the time I had little or no interest in diving in personally. Burr-Brown invested heavily in designing ICs for the upcoming market demand, but as history tells us, it didn't become mainstream. Certainly not in the US, less so in Europe, but in Japan there was always demand. Philips and Sony originally developed SACD as the high end next generation of CD, and certainly the format was capable of encoding a significantly higher level of audio information on the platform. DSD was a delta-sigma bitstream format that sampled 1-bit at 2.8MHz. Philips Semiconductors (amongst others) developed an SACD processor and Burr-Brown (amongst others) developed DSD Digital to Analog converters. L...

The photo above shows a hybrid technology 12-bit D/A Converter from Burr-Brown Corporation. By 1986 this was replaced by a monolithic i.e. single chip design. Under the metal lid is a ceramic substrate based multi-chip module. See below for examples of the technology. DAC85 is the model number. The 1st C is the operating temp range (0 to 70C). CBI is complementary bipolar inputs and V is the voltage output version. 12-bit DACs from Burr-Brown were used primarily in industrial applications like automation and factory control. If you only know DACs for digital audio, then 12 bit may seem a low resolution, but parameters that were most important for high end industrial use would not be relevant for audio. These DACs were very precise.

Burr-Brown PCM1702-L I've just acquired from eBay a CD player to complement another very old CD player, both with Burr-Brown Digital to Analog converters. The photo shows the inside of the Denon CD-655 from the late 90s, a super low distortion and high signal to noise ratio CD player which uses 2 x PCM1702 DACs from Burr-Brown. The BiCMOS process 20-Bit PCM1702 was a really interesting DAC which was an improved version of the PCM63P. Early R-2R ladder DACs suffered from some noise/glitches at low output levels (and degraded linearity) due to the Most Significant Bit current source turning on at the lowest volume output point. Multi-bit DACs had significantly higher performance than contemporary 1-bit and "MASH" DACs, but had this one flaw. The PCM1702 was effectively two 19-bit DACs in a complementary design which negated the zero cross point issue. They had all the benefits of R-2R ladder DACs and now removed the other issue. Around this time Burr-Brown were al...